Fix multiple vulnerabilities of ntp. [SA-17:03]

[FreeBSD/releng/10.3.git] / contrib / ntp / util / ntp-keygen.c

/*
 * Program to generate cryptographic keys for ntp clients and servers
 *
 * This program generates password encrypted data files for use with the
 * Autokey security protocol and Network Time Protocol Version 4. Files
 * are prefixed with a header giving the name and date of creation
 * followed by a type-specific descriptive label and PEM-encoded data
 * structure compatible with programs of the OpenSSL library.
 *
 * All file names are like "ntpkey_<type>_<hostname>.<filestamp>", where
 * <type> is the file type, <hostname> the generating host name and
 * <filestamp> the generation time in NTP seconds. The NTP programs
 * expect generic names such as "ntpkey_<type>_whimsy.udel.edu" with the
 * association maintained by soft links. Following is a list of file
 * types; the first line is the file name and the second link name.
 *
 * ntpkey_MD5key_<hostname>.<filestamp>
 *      MD5 (128-bit) keys used to compute message digests in symmetric
 *      key cryptography
 *
 * ntpkey_RSAhost_<hostname>.<filestamp>
 * ntpkey_host_<hostname>
 *      RSA private/public host key pair used for public key signatures
 *
 * ntpkey_RSAsign_<hostname>.<filestamp>
 * ntpkey_sign_<hostname>
 *      RSA private/public sign key pair used for public key signatures
 *
 * ntpkey_DSAsign_<hostname>.<filestamp>
 * ntpkey_sign_<hostname>
 *      DSA Private/public sign key pair used for public key signatures
 *
 * Available digest/signature schemes
 *
 * RSA: RSA-MD2, RSA-MD5, RSA-SHA, RSA-SHA1, RSA-MDC2, EVP-RIPEMD160
 * DSA: DSA-SHA, DSA-SHA1
 *
 * ntpkey_XXXcert_<hostname>.<filestamp>
 * ntpkey_cert_<hostname>
 *      X509v3 certificate using RSA or DSA public keys and signatures.
 *      XXX is a code identifying the message digest and signature
 *      encryption algorithm
 *
 * Identity schemes. The key type par is used for the challenge; the key
 * type key is used for the response.
 *
 * ntpkey_IFFkey_<groupname>.<filestamp>
 * ntpkey_iffkey_<groupname>
 *      Schnorr (IFF) identity parameters and keys
 *
 * ntpkey_GQkey_<groupname>.<filestamp>,
 * ntpkey_gqkey_<groupname>
 *      Guillou-Quisquater (GQ) identity parameters and keys
 *
 * ntpkey_MVkeyX_<groupname>.<filestamp>,
 * ntpkey_mvkey_<groupname>
 *      Mu-Varadharajan (MV) identity parameters and keys
 *
 * Note: Once in a while because of some statistical fluke this program
 * fails to generate and verify some cryptographic data, as indicated by
 * exit status -1. In this case simply run the program again. If the
 * program does complete with exit code 0, the data are correct as
 * verified.
 *
 * These cryptographic routines are characterized by the prime modulus
 * size in bits. The default value of 512 bits is a compromise between
 * cryptographic strength and computing time and is ordinarily
 * considered adequate for this application. The routines have been
 * tested with sizes of 256, 512, 1024 and 2048 bits. Not all message
 * digest and signature encryption schemes work with sizes less than 512
 * bits. The computing time for sizes greater than 2048 bits is
 * prohibitive on all but the fastest processors. An UltraSPARC Blade
 * 1000 took something over nine minutes to generate and verify the
 * values with size 2048. An old SPARC IPC would take a week.
 *
 * The OpenSSL library used by this program expects a random seed file.
 * As described in the OpenSSL documentation, the file name defaults to
 * first the RANDFILE environment variable in the user's home directory
 * and then .rnd in the user's home directory.
 */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>

#include "ntp.h"
#include "ntp_random.h"
#include "ntp_stdlib.h"
#include "ntp_assert.h"
#include "ntp_libopts.h"
#include "ntp_unixtime.h"
#include "ntp-keygen-opts.h"

#ifdef OPENSSL
#include "openssl/asn1.h"
#include "openssl/bn.h"
#include "openssl/crypto.h"
#include "openssl/evp.h"
#include "openssl/err.h"
#include "openssl/rand.h"
#include "openssl/opensslv.h"
#include "openssl/pem.h"
#include "openssl/x509.h"
#include "openssl/x509v3.h"
#include <openssl/objects.h>
#include "libssl_compat.h"
#endif  /* OPENSSL */
#include <ssl_applink.c>

#define _UC(str)        ((char *)(intptr_t)(str))
/*
 * Cryptodefines
 */
#define MD5KEYS         10      /* number of keys generated of each type */
#define MD5SIZE         20      /* maximum key size */
#ifdef AUTOKEY
#define PLEN            512     /* default prime modulus size (bits) */
#define ILEN            256     /* default identity modulus size (bits) */
#define MVMAX           100     /* max MV parameters */

/*
 * Strings used in X509v3 extension fields
 */
#define KEY_USAGE               "digitalSignature,keyCertSign"
#define BASIC_CONSTRAINTS       "critical,CA:TRUE"
#define EXT_KEY_PRIVATE         "private"
#define EXT_KEY_TRUST           "trustRoot"
#endif  /* AUTOKEY */

/*
 * Prototypes
 */
FILE    *fheader        (const char *, const char *, const char *);
int     gen_md5         (const char *);
void    followlink      (char *, size_t);
#ifdef AUTOKEY
EVP_PKEY *gen_rsa       (const char *);
EVP_PKEY *gen_dsa       (const char *);
EVP_PKEY *gen_iffkey    (const char *);
EVP_PKEY *gen_gqkey     (const char *);
EVP_PKEY *gen_mvkey     (const char *, EVP_PKEY **);
void    gen_mvserv      (char *, EVP_PKEY **);
int     x509            (EVP_PKEY *, const EVP_MD *, char *, const char *,
                            char *);
void    cb              (int, int, void *);
EVP_PKEY *genkey        (const char *, const char *);
EVP_PKEY *readkey       (char *, char *, u_int *, EVP_PKEY **);
void    writekey        (char *, char *, u_int *, EVP_PKEY **);
u_long  asn2ntp         (ASN1_TIME *);

static DSA* genDsaParams(int, char*);
static RSA* genRsaKeyPair(int, char*);

#endif  /* AUTOKEY */

/*
 * Program variables
 */
extern char *optarg;            /* command line argument */
char    const *progname;
u_int   lifetime = DAYSPERYEAR; /* certificate lifetime (days) */
int     nkeys;                  /* MV keys */
time_t  epoch;                  /* Unix epoch (seconds) since 1970 */
u_int   fstamp;                 /* NTP filestamp */
char    hostbuf[MAXHOSTNAME + 1];
char    *hostname = NULL;       /* host, used in cert filenames */
char    *groupname = NULL;      /* group name */
char    certnamebuf[2 * sizeof(hostbuf)];
char    *certname = NULL;       /* certificate subject/issuer name */
char    *passwd1 = NULL;        /* input private key password */
char    *passwd2 = NULL;        /* output private key password */
char    filename[MAXFILENAME + 1]; /* file name */
#ifdef AUTOKEY
u_int   modulus = PLEN;         /* prime modulus size (bits) */
u_int   modulus2 = ILEN;        /* identity modulus size (bits) */
long    d0, d1, d2, d3;         /* callback counters */
const EVP_CIPHER * cipher = NULL;
#endif  /* AUTOKEY */

#ifdef SYS_WINNT
BOOL init_randfile();

/*
 * Don't try to follow symbolic links on Windows.  Assume link == file.
 */
int
readlink(
        char *  link,
        char *  file,
        int     len
        )
{
        return (int)strlen(file); /* assume no overflow possible */
}

/*
 * Don't try to create symbolic links on Windows, that is supported on
 * Vista and later only.  Instead, if CreateHardLink is available (XP
 * and later), hardlink the linkname to the original filename.  On
 * earlier systems, user must rename file to match expected link for
 * ntpd to find it.  To allow building a ntp-keygen.exe which loads on
 * Windows pre-XP, runtime link to CreateHardLinkA().
 */
int
symlink(
        char *  filename,
        char*   linkname
        )
{
        typedef BOOL (WINAPI *PCREATEHARDLINKA)(
                __in LPCSTR     lpFileName,
                __in LPCSTR     lpExistingFileName,
                __reserved LPSECURITY_ATTRIBUTES lpSA
                );
        static PCREATEHARDLINKA pCreateHardLinkA;
        static int              tried;
        HMODULE                 hDll;
        FARPROC                 pfn;
        int                     link_created;
        int                     saved_errno;

        if (!tried) {
                tried = TRUE;
                hDll = LoadLibrary("kernel32");
                pfn = GetProcAddress(hDll, "CreateHardLinkA");
                pCreateHardLinkA = (PCREATEHARDLINKA)pfn;
        }

        if (NULL == pCreateHardLinkA) {
                errno = ENOSYS;
                return -1;
        }

        link_created = (*pCreateHardLinkA)(linkname, filename, NULL);
        
        if (link_created)
                return 0;

        saved_errno = GetLastError();   /* yes we play loose */
        mfprintf(stderr, "Create hard link %s to %s failed: %m\n",
                 linkname, filename);
        errno = saved_errno;
        return -1;
}

void
InitWin32Sockets() {
        WORD wVersionRequested;
        WSADATA wsaData;
        wVersionRequested = MAKEWORD(2,0);
        if (WSAStartup(wVersionRequested, &wsaData))
        {
                fprintf(stderr, "No useable winsock.dll\n");
                exit(1);
        }
}
#endif /* SYS_WINNT */


/*
 * followlink() - replace filename with its target if symlink.
 *
 * Some readlink() implementations do not null-terminate the result.
 */
void
followlink(
        char *  fname,
        size_t  bufsiz
        )
{
        int len;

        REQUIRE(bufsiz > 0);

        len = readlink(fname, fname, (int)bufsiz);
        if (len < 0 ) {
                fname[0] = '\0';
                return;
        }
        if (len > (int)bufsiz - 1)
                len = (int)bufsiz - 1;
        fname[len] = '\0';
}


/*
 * Main program
 */
int
main(
        int     argc,           /* command line options */
        char    **argv
        )
{
        struct timeval tv;      /* initialization vector */
        int     md5key = 0;     /* generate MD5 keys */
        int     optct;          /* option count */
#ifdef AUTOKEY
        X509    *cert = NULL;   /* X509 certificate */
        EVP_PKEY *pkey_host = NULL; /* host key */
        EVP_PKEY *pkey_sign = NULL; /* sign key */
        EVP_PKEY *pkey_iffkey = NULL; /* IFF sever keys */
        EVP_PKEY *pkey_gqkey = NULL; /* GQ server keys */
        EVP_PKEY *pkey_mvkey = NULL; /* MV trusted agen keys */
        EVP_PKEY *pkey_mvpar[MVMAX]; /* MV cleient keys */
        int     hostkey = 0;    /* generate RSA keys */
        int     iffkey = 0;     /* generate IFF keys */
        int     gqkey = 0;      /* generate GQ keys */
        int     mvkey = 0;      /* update MV keys */
        int     mvpar = 0;      /* generate MV parameters */
        char    *sign = NULL;   /* sign key */
        EVP_PKEY *pkey = NULL;  /* temp key */
        const EVP_MD *ectx;     /* EVP digest */
        char    pathbuf[MAXFILENAME + 1];
        const char *scheme = NULL; /* digest/signature scheme */
        const char *ciphername = NULL; /* to encrypt priv. key */
        const char *exten = NULL;       /* private extension */
        char    *grpkey = NULL; /* identity extension */
        int     nid;            /* X509 digest/signature scheme */
        FILE    *fstr = NULL;   /* file handle */
        char    groupbuf[MAXHOSTNAME + 1];
        u_int   temp;
        BIO *   bp;
        int     i, cnt;
        char *  ptr;
#endif  /* AUTOKEY */
#ifdef OPENSSL
        const char *sslvtext;
        int sslvmatch;
#endif /* OPENSSL */

        progname = argv[0];

#ifdef SYS_WINNT
        /* Initialize before OpenSSL checks */
        InitWin32Sockets();
        if (!init_randfile())
                fprintf(stderr, "Unable to initialize .rnd file\n");
        ssl_applink();
#endif

#ifdef OPENSSL
        ssl_check_version();
#endif  /* OPENSSL */

        ntp_crypto_srandom();

        /*
         * Process options, initialize host name and timestamp.
         * gethostname() won't null-terminate if hostname is exactly the
         * length provided for the buffer.
         */
        gethostname(hostbuf, sizeof(hostbuf) - 1);
        hostbuf[COUNTOF(hostbuf) - 1] = '\0';
        hostname = hostbuf;
        groupname = hostbuf;
        passwd1 = hostbuf;
        passwd2 = NULL;
        GETTIMEOFDAY(&tv, NULL);
        epoch = tv.tv_sec;
        fstamp = (u_int)(epoch + JAN_1970);

        optct = ntpOptionProcess(&ntp_keygenOptions, argc, argv);
        argc -= optct;  // Just in case we care later.
        argv += optct;  // Just in case we care later.

#ifdef OPENSSL
        sslvtext = OpenSSL_version(OPENSSL_VERSION);
        sslvmatch = OpenSSL_version_num() == OPENSSL_VERSION_NUMBER;
        if (sslvmatch)
                fprintf(stderr, "Using OpenSSL version %s\n",
                        sslvtext);
        else
                fprintf(stderr, "Built against OpenSSL %s, using version %s\n",
                        OPENSSL_VERSION_TEXT, sslvtext);
#endif /* OPENSSL */

        debug = OPT_VALUE_SET_DEBUG_LEVEL;

        if (HAVE_OPT( MD5KEY ))
                md5key++;
#ifdef AUTOKEY
        if (HAVE_OPT( PASSWORD ))
                passwd1 = estrdup(OPT_ARG( PASSWORD ));

        if (HAVE_OPT( EXPORT_PASSWD ))
                passwd2 = estrdup(OPT_ARG( EXPORT_PASSWD ));

        if (HAVE_OPT( HOST_KEY ))
                hostkey++;

        if (HAVE_OPT( SIGN_KEY ))
                sign = estrdup(OPT_ARG( SIGN_KEY ));

        if (HAVE_OPT( GQ_PARAMS ))
                gqkey++;

        if (HAVE_OPT( IFFKEY ))
                iffkey++;

        if (HAVE_OPT( MV_PARAMS )) {
                mvkey++;
                nkeys = OPT_VALUE_MV_PARAMS;
        }
        if (HAVE_OPT( MV_KEYS )) {
                mvpar++;
                nkeys = OPT_VALUE_MV_KEYS;
        }

        if (HAVE_OPT( IMBITS ))
                modulus2 = OPT_VALUE_IMBITS;

        if (HAVE_OPT( MODULUS ))
                modulus = OPT_VALUE_MODULUS;

        if (HAVE_OPT( CERTIFICATE ))
                scheme = OPT_ARG( CERTIFICATE );

        if (HAVE_OPT( CIPHER ))
                ciphername = OPT_ARG( CIPHER );

        if (HAVE_OPT( SUBJECT_NAME ))
                hostname = estrdup(OPT_ARG( SUBJECT_NAME ));

        if (HAVE_OPT( IDENT ))
                groupname = estrdup(OPT_ARG( IDENT ));

        if (HAVE_OPT( LIFETIME ))
                lifetime = OPT_VALUE_LIFETIME;

        if (HAVE_OPT( PVT_CERT ))
                exten = EXT_KEY_PRIVATE;

        if (HAVE_OPT( TRUSTED_CERT ))
                exten = EXT_KEY_TRUST;

        /*
         * Remove the group name from the hostname variable used
         * in host and sign certificate file names.
         */
        if (hostname != hostbuf)
                ptr = strchr(hostname, '@');
        else
                ptr = NULL;
        if (ptr != NULL) {
                *ptr = '\0';
                groupname = estrdup(ptr + 1);
                /* -s @group is equivalent to -i group, host unch. */
                if (ptr == hostname)
                        hostname = hostbuf;
        }

        /*
         * Derive host certificate issuer/subject names from host name
         * and optional group.  If no groupname is provided, the issuer
         * and subject is the hostname with no '@group', and the
         * groupname variable is pointed to hostname for use in IFF, GQ,
         * and MV parameters file names.
         */
        if (groupname == hostbuf) {
                certname = hostname;
        } else {
                snprintf(certnamebuf, sizeof(certnamebuf), "%s@%s",
                         hostname, groupname);
                certname = certnamebuf;
        }

        /*
         * Seed random number generator and grow weeds.
         */
#if OPENSSL_VERSION_NUMBER < 0x10100000L
        ERR_load_crypto_strings();
        OpenSSL_add_all_algorithms();
#endif /* OPENSSL_VERSION_NUMBER */
        if (!RAND_status()) {
                if (RAND_file_name(pathbuf, sizeof(pathbuf)) == NULL) {
                        fprintf(stderr, "RAND_file_name %s\n",
                            ERR_error_string(ERR_get_error(), NULL));
                        exit (-1);
                }
                temp = RAND_load_file(pathbuf, -1);
                if (temp == 0) {
                        fprintf(stderr,
                            "RAND_load_file %s not found or empty\n",
                            pathbuf);
                        exit (-1);
                }
                fprintf(stderr,
                    "Random seed file %s %u bytes\n", pathbuf, temp);
                RAND_add(&epoch, sizeof(epoch), 4.0);
        }
#endif  /* AUTOKEY */

        /*
         * Create new unencrypted MD5 keys file if requested. If this
         * option is selected, ignore all other options.
         */
        if (md5key) {
                gen_md5("md5");
                exit (0);
        }

#ifdef AUTOKEY
        /*
         * Load previous certificate if available.
         */
        snprintf(filename, sizeof(filename), "ntpkey_cert_%s", hostname);
        if ((fstr = fopen(filename, "r")) != NULL) {
                cert = PEM_read_X509(fstr, NULL, NULL, NULL);
                fclose(fstr);
        }
        if (cert != NULL) {

                /*
                 * Extract subject name.
                 */
                X509_NAME_oneline(X509_get_subject_name(cert), groupbuf,
                    MAXFILENAME);

                /*
                 * Extract digest/signature scheme.
                 */
                if (scheme == NULL) {
                        nid = X509_get_signature_nid(cert);
                        scheme = OBJ_nid2sn(nid);
                }

                /*
                 * If a key_usage extension field is present, determine
                 * whether this is a trusted or private certificate.
                 */
                if (exten == NULL) {
                        ptr = strstr(groupbuf, "CN=");
                        cnt = X509_get_ext_count(cert);
                        for (i = 0; i < cnt; i++) {
                                X509_EXTENSION *ext;
                                ASN1_OBJECT *obj;

                                ext = X509_get_ext(cert, i);
                                obj = X509_EXTENSION_get_object(ext);

                                if (OBJ_obj2nid(obj) ==
                                    NID_ext_key_usage) {
                                        bp = BIO_new(BIO_s_mem());
                                        X509V3_EXT_print(bp, ext, 0, 0);
                                        BIO_gets(bp, pathbuf,
                                            MAXFILENAME);
                                        BIO_free(bp);
                                        if (strcmp(pathbuf,
                                            "Trust Root") == 0)
                                                exten = EXT_KEY_TRUST;
                                        else if (strcmp(pathbuf,
                                            "Private") == 0)
                                                exten = EXT_KEY_PRIVATE;
                                        certname = estrdup(ptr + 3);
                                }
                        }
                }
        }
        if (scheme == NULL)
                scheme = "RSA-MD5";
        if (ciphername == NULL)
                ciphername = "des-ede3-cbc";
        cipher = EVP_get_cipherbyname(ciphername);
        if (cipher == NULL) {
                fprintf(stderr, "Unknown cipher %s\n", ciphername);
                exit(-1);
        }
        fprintf(stderr, "Using host %s group %s\n", hostname,
            groupname);

        /*
         * Create a new encrypted RSA host key file if requested;
         * otherwise, look for an existing host key file. If not found,
         * create a new encrypted RSA host key file. If that fails, go
         * no further.
         */
        if (hostkey)
                pkey_host = genkey("RSA", "host");
        if (pkey_host == NULL) {
                snprintf(filename, sizeof(filename), "ntpkey_host_%s", hostname);
                pkey_host = readkey(filename, passwd1, &fstamp, NULL);
                if (pkey_host != NULL) {
                        followlink(filename, sizeof(filename));
                        fprintf(stderr, "Using host key %s\n",
                            filename);
                } else {
                        pkey_host = genkey("RSA", "host");
                }
        }
        if (pkey_host == NULL) {
                fprintf(stderr, "Generating host key fails\n");
                exit(-1);
        }

        /*
         * Create new encrypted RSA or DSA sign keys file if requested;
         * otherwise, look for an existing sign key file. If not found,
         * use the host key instead.
         */
        if (sign != NULL)
                pkey_sign = genkey(sign, "sign");
        if (pkey_sign == NULL) {
                snprintf(filename, sizeof(filename), "ntpkey_sign_%s",
                         hostname);
                pkey_sign = readkey(filename, passwd1, &fstamp, NULL);
                if (pkey_sign != NULL) {
                        followlink(filename, sizeof(filename));
                        fprintf(stderr, "Using sign key %s\n",
                            filename);
                } else {
                        pkey_sign = pkey_host;
                        fprintf(stderr, "Using host key as sign key\n");
                }
        }

        /*
         * Create new encrypted GQ server keys file if requested;
         * otherwise, look for an exisiting file. If found, fetch the
         * public key for the certificate.
         */
        if (gqkey)
                pkey_gqkey = gen_gqkey("gqkey");
        if (pkey_gqkey == NULL) {
                snprintf(filename, sizeof(filename), "ntpkey_gqkey_%s",
                    groupname);
                pkey_gqkey = readkey(filename, passwd1, &fstamp, NULL);
                if (pkey_gqkey != NULL) {
                        followlink(filename, sizeof(filename));
                        fprintf(stderr, "Using GQ parameters %s\n",
                            filename);
                }
        }
        if (pkey_gqkey != NULL) {
                RSA     *rsa;
                const BIGNUM *q;

                rsa = EVP_PKEY_get0_RSA(pkey_gqkey);
                RSA_get0_factors(rsa, NULL, &q);
                grpkey = BN_bn2hex(q);
        }

        /*
         * Write the nonencrypted GQ client parameters to the stdout
         * stream. The parameter file is the server key file with the
         * private key obscured.
         */
        if (pkey_gqkey != NULL && HAVE_OPT(ID_KEY)) {
                RSA     *rsa;

                snprintf(filename, sizeof(filename),
                    "ntpkey_gqpar_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing GQ parameters %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                /* XXX: This modifies the private key and should probably use a
                 * copy of it instead. */
                rsa = EVP_PKEY_get0_RSA(pkey_gqkey);
                RSA_set0_factors(rsa, BN_dup(BN_value_one()), BN_dup(BN_value_one()));
                pkey = EVP_PKEY_new();
                EVP_PKEY_assign_RSA(pkey, rsa);
                PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
                    NULL, NULL);
                fflush(stdout);
                if (debug)
                        RSA_print_fp(stderr, rsa, 0);
        }

        /*
         * Write the encrypted GQ server keys to the stdout stream.
         */
        if (pkey_gqkey != NULL && passwd2 != NULL) {
                RSA     *rsa;

                snprintf(filename, sizeof(filename),
                    "ntpkey_gqkey_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing GQ keys %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                rsa = EVP_PKEY_get0_RSA(pkey_gqkey);
                pkey = EVP_PKEY_new();
                EVP_PKEY_assign_RSA(pkey, rsa);
                PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
                    NULL, passwd2);
                fflush(stdout);
                if (debug)
                        RSA_print_fp(stderr, rsa, 0);
        }

        /*
         * Create new encrypted IFF server keys file if requested;
         * otherwise, look for existing file.
         */
        if (iffkey)
                pkey_iffkey = gen_iffkey("iffkey");
        if (pkey_iffkey == NULL) {
                snprintf(filename, sizeof(filename), "ntpkey_iffkey_%s",
                    groupname);
                pkey_iffkey = readkey(filename, passwd1, &fstamp, NULL);
                if (pkey_iffkey != NULL) {
                        followlink(filename, sizeof(filename));
                        fprintf(stderr, "Using IFF keys %s\n",
                            filename);
                }
        }

        /*
         * Write the nonencrypted IFF client parameters to the stdout
         * stream. The parameter file is the server key file with the
         * private key obscured.
         */
        if (pkey_iffkey != NULL && HAVE_OPT(ID_KEY)) {
                DSA     *dsa;

                snprintf(filename, sizeof(filename),
                    "ntpkey_iffpar_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing IFF parameters %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                /* XXX: This modifies the private key and should probably use a
                 * copy of it instead. */
                dsa = EVP_PKEY_get0_DSA(pkey_iffkey);
                DSA_set0_key(dsa, NULL, BN_dup(BN_value_one()));
                pkey = EVP_PKEY_new();
                EVP_PKEY_assign_DSA(pkey, dsa);
                PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
                    NULL, NULL);
                fflush(stdout);
                if (debug)
                        DSA_print_fp(stderr, dsa, 0);
        }

        /*
         * Write the encrypted IFF server keys to the stdout stream.
         */
        if (pkey_iffkey != NULL && passwd2 != NULL) {
                DSA     *dsa;

                snprintf(filename, sizeof(filename),
                    "ntpkey_iffkey_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing IFF keys %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                dsa = EVP_PKEY_get0_DSA(pkey_iffkey);
                pkey = EVP_PKEY_new();
                EVP_PKEY_assign_DSA(pkey, dsa);
                PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
                    NULL, passwd2);
                fflush(stdout);
                if (debug)
                        DSA_print_fp(stderr, dsa, 0);
        }

        /*
         * Create new encrypted MV trusted-authority keys file if
         * requested; otherwise, look for existing keys file.
         */
        if (mvkey)
                pkey_mvkey = gen_mvkey("mv", pkey_mvpar);
        if (pkey_mvkey == NULL) {
                snprintf(filename, sizeof(filename), "ntpkey_mvta_%s",
                    groupname);
                pkey_mvkey = readkey(filename, passwd1, &fstamp,
                    pkey_mvpar);
                if (pkey_mvkey != NULL) {
                        followlink(filename, sizeof(filename));
                        fprintf(stderr, "Using MV keys %s\n",
                            filename);
                }
        }

        /*
         * Write the nonencrypted MV client parameters to the stdout
         * stream. For the moment, we always use the client parameters
         * associated with client key 1.
         */
        if (pkey_mvkey != NULL && HAVE_OPT(ID_KEY)) {
                snprintf(filename, sizeof(filename),
                    "ntpkey_mvpar_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing MV parameters %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                pkey = pkey_mvpar[2];
                PEM_write_PKCS8PrivateKey(stdout, pkey, NULL, NULL, 0,
                    NULL, NULL);
                fflush(stdout);
                if (debug)
                        DSA_print_fp(stderr, EVP_PKEY_get0_DSA(pkey), 0);
        }

        /*
         * Write the encrypted MV server keys to the stdout stream.
         */
        if (pkey_mvkey != NULL && passwd2 != NULL) {
                snprintf(filename, sizeof(filename),
                    "ntpkey_mvkey_%s.%u", groupname, fstamp);
                fprintf(stderr, "Writing MV keys %s to stdout\n",
                    filename);
                fprintf(stdout, "# %s\n# %s\n", filename,
                    ctime(&epoch));
                pkey = pkey_mvpar[1];
                PEM_write_PKCS8PrivateKey(stdout, pkey, cipher, NULL, 0,
                    NULL, passwd2);
                fflush(stdout);
                if (debug)
                        DSA_print_fp(stderr, EVP_PKEY_get0_DSA(pkey), 0);
        }

        /*
         * Decode the digest/signature scheme and create the
         * certificate. Do this every time we run the program.
         */
        ectx = EVP_get_digestbyname(scheme);
        if (ectx == NULL) {
                fprintf(stderr,
                    "Invalid digest/signature combination %s\n",
                    scheme);
                        exit (-1);
        }
        x509(pkey_sign, ectx, grpkey, exten, certname);
#endif  /* AUTOKEY */
        exit(0);
}


/*
 * Generate semi-random MD5 keys compatible with NTPv3 and NTPv4. Also,
 * if OpenSSL is around, generate random SHA1 keys compatible with
 * symmetric key cryptography.
 */
int
gen_md5(
        const char *id          /* file name id */
        )
{
        u_char  md5key[MD5SIZE + 1];    /* MD5 key */
        FILE    *str;
        int     i, j;
#ifdef OPENSSL
        u_char  keystr[MD5SIZE];
        u_char  hexstr[2 * MD5SIZE + 1];
        u_char  hex[] = "0123456789abcdef";
#endif  /* OPENSSL */

        str = fheader("MD5key", id, groupname);
        for (i = 1; i <= MD5KEYS; i++) {
                for (j = 0; j < MD5SIZE; j++) {
                        u_char temp;

                        while (1) {
                                int rc;

                                rc = ntp_crypto_random_buf(
                                    &temp, sizeof(temp));
                                if (-1 == rc) {
                                        fprintf(stderr, "ntp_crypto_random_buf() failed.\n");
                                        exit (-1);
                                }
                                if (temp == '#')
                                        continue;

                                if (temp > 0x20 && temp < 0x7f)
                                        break;
                        }
                        md5key[j] = temp;
                }
                md5key[j] = '\0';
                fprintf(str, "%2d MD5 %s  # MD5 key\n", i,
                    md5key);
        }
#ifdef OPENSSL
        for (i = 1; i <= MD5KEYS; i++) {
                RAND_bytes(keystr, 20);
                for (j = 0; j < MD5SIZE; j++) {
                        hexstr[2 * j] = hex[keystr[j] >> 4];
                        hexstr[2 * j + 1] = hex[keystr[j] & 0xf];
                }
                hexstr[2 * MD5SIZE] = '\0';
                fprintf(str, "%2d SHA1 %s  # SHA1 key\n", i + MD5KEYS,
                    hexstr);
        }
#endif  /* OPENSSL */
        fclose(str);
        return (1);
}


#ifdef AUTOKEY
/*
 * readkey - load cryptographic parameters and keys
 *
 * This routine loads a PEM-encoded file of given name and password and
 * extracts the filestamp from the file name. It returns a pointer to
 * the first key if valid, NULL if not.
 */
EVP_PKEY *                      /* public/private key pair */
readkey(
        char    *cp,            /* file name */
        char    *passwd,        /* password */
        u_int   *estamp,        /* file stamp */
        EVP_PKEY **evpars       /* parameter list pointer */
        )
{
        FILE    *str;           /* file handle */
        EVP_PKEY *pkey = NULL;  /* public/private key */
        u_int   gstamp;         /* filestamp */
        char    linkname[MAXFILENAME]; /* filestamp buffer) */
        EVP_PKEY *parkey;
        char    *ptr;
        int     i;

        /*
         * Open the key file.
         */
        str = fopen(cp, "r");
        if (str == NULL)
                return (NULL);

        /*
         * Read the filestamp, which is contained in the first line.
         */
        if ((ptr = fgets(linkname, MAXFILENAME, str)) == NULL) {
                fprintf(stderr, "Empty key file %s\n", cp);
                fclose(str);
                return (NULL);
        }
        if ((ptr = strrchr(ptr, '.')) == NULL) {
                fprintf(stderr, "No filestamp found in %s\n", cp);
                fclose(str);
                return (NULL);
        }
        if (sscanf(++ptr, "%u", &gstamp) != 1) {
                fprintf(stderr, "Invalid filestamp found in %s\n", cp);
                fclose(str);
                return (NULL);
        }

        /*
         * Read and decrypt PEM-encoded private keys. The first one
         * found is returned. If others are expected, add them to the
         * parameter list.
         */
        for (i = 0; i <= MVMAX - 1;) {
                parkey = PEM_read_PrivateKey(str, NULL, NULL, passwd);
                if (evpars != NULL) {
                        evpars[i++] = parkey;
                        evpars[i] = NULL;
                }
                if (parkey == NULL)
                        break;

                if (pkey == NULL)
                        pkey = parkey;
                if (debug) {
                        if (EVP_PKEY_base_id(parkey) == EVP_PKEY_DSA)
                                DSA_print_fp(stderr, EVP_PKEY_get0_DSA(parkey),
                                    0);
                        else if (EVP_PKEY_base_id(parkey) == EVP_PKEY_RSA)
                                RSA_print_fp(stderr, EVP_PKEY_get0_RSA(parkey),
                                    0);
                }
        }
        fclose(str);
        if (pkey == NULL) {
                fprintf(stderr, "Corrupt file %s or wrong key %s\n%s\n",
                    cp, passwd, ERR_error_string(ERR_get_error(),
                    NULL));
                exit (-1);
        }
        *estamp = gstamp;
        return (pkey);
}


/*
 * Generate RSA public/private key pair
 */
EVP_PKEY *                      /* public/private key pair */
gen_rsa(
        const char *id          /* file name id */
        )
{
        EVP_PKEY *pkey;         /* private key */
        RSA     *rsa;           /* RSA parameters and key pair */
        FILE    *str;

        fprintf(stderr, "Generating RSA keys (%d bits)...\n", modulus);
        rsa = genRsaKeyPair(modulus, _UC("RSA"));
        fprintf(stderr, "\n");
        if (rsa == NULL) {
                fprintf(stderr, "RSA generate keys fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (NULL);
        }

        /*
         * For signature encryption it is not necessary that the RSA
         * parameters be strictly groomed and once in a while the
         * modulus turns out to be non-prime. Just for grins, we check
         * the primality.
         */
        if (!RSA_check_key(rsa)) {
                fprintf(stderr, "Invalid RSA key\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                RSA_free(rsa);
                return (NULL);
        }

        /*
         * Write the RSA parameters and keys as a RSA private key
         * encoded in PEM.
         */
        if (strcmp(id, "sign") == 0)
                str = fheader("RSAsign", id, hostname);
        else
                str = fheader("RSAhost", id, hostname);
        pkey = EVP_PKEY_new();
        EVP_PKEY_assign_RSA(pkey, rsa);
        PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
            passwd1);
        fclose(str);
        if (debug)
                RSA_print_fp(stderr, rsa, 0);
        return (pkey);
}


/*
 * Generate DSA public/private key pair
 */
EVP_PKEY *                      /* public/private key pair */
gen_dsa(
        const char *id          /* file name id */
        )
{
        EVP_PKEY *pkey;         /* private key */
        DSA     *dsa;           /* DSA parameters */
        FILE    *str;

        /*
         * Generate DSA parameters.
         */
        fprintf(stderr,
            "Generating DSA parameters (%d bits)...\n", modulus);
        dsa = genDsaParams(modulus, _UC("DSA"));
        fprintf(stderr, "\n");
        if (dsa == NULL) {
                fprintf(stderr, "DSA generate parameters fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (NULL);
        }

        /*
         * Generate DSA keys.
         */
        fprintf(stderr, "Generating DSA keys (%d bits)...\n", modulus);
        if (!DSA_generate_key(dsa)) {
                fprintf(stderr, "DSA generate keys fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                DSA_free(dsa);
                return (NULL);
        }

        /*
         * Write the DSA parameters and keys as a DSA private key
         * encoded in PEM.
         */
        str = fheader("DSAsign", id, hostname);
        pkey = EVP_PKEY_new();
        EVP_PKEY_assign_DSA(pkey, dsa);
        PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
            passwd1);
        fclose(str);
        if (debug)
                DSA_print_fp(stderr, dsa, 0);
        return (pkey);
}


/*
 ***********************************************************************
 *                                                                     *
 * The following routines implement the Schnorr (IFF) identity scheme  *
 *                                                                     *
 ***********************************************************************
 *
 * The Schnorr (IFF) identity scheme is intended for use when
 * certificates are generated by some other trusted certificate
 * authority and the certificate cannot be used to convey public
 * parameters. There are two kinds of files: encrypted server files that
 * contain private and public values and nonencrypted client files that
 * contain only public values. New generations of server files must be
 * securely transmitted to all servers of the group; client files can be
 * distributed by any means. The scheme is self contained and
 * independent of new generations of host keys, sign keys and
 * certificates.
 *
 * The IFF values hide in a DSA cuckoo structure which uses the same
 * parameters. The values are used by an identity scheme based on DSA
 * cryptography and described in Stimson p. 285. The p is a 512-bit
 * prime, g a generator of Zp* and q a 160-bit prime that divides p - 1
 * and is a qth root of 1 mod p; that is, g^q = 1 mod p. The TA rolls a
 * private random group key b (0 < b < q) and public key v = g^b, then
 * sends (p, q, g, b) to the servers and (p, q, g, v) to the clients.
 * Alice challenges Bob to confirm identity using the protocol described
 * below.
 *
 * How it works
 *
 * The scheme goes like this. Both Alice and Bob have the public primes
 * p, q and generator g. The TA gives private key b to Bob and public
 * key v to Alice.
 *
 * Alice rolls new random challenge r (o < r < q) and sends to Bob in
 * the IFF request message. Bob rolls new random k (0 < k < q), then
 * computes y = k + b r mod q and x = g^k mod p and sends (y, hash(x))
 * to Alice in the response message. Besides making the response
 * shorter, the hash makes it effectivey impossible for an intruder to
 * solve for b by observing a number of these messages.
 * 
 * Alice receives the response and computes g^y v^r mod p. After a bit
 * of algebra, this simplifies to g^k. If the hash of this result
 * matches hash(x), Alice knows that Bob has the group key b. The signed
 * response binds this knowledge to Bob's private key and the public key
 * previously received in his certificate.
 */
/*
 * Generate Schnorr (IFF) keys.
 */
EVP_PKEY *                      /* DSA cuckoo nest */
gen_iffkey(
        const char *id          /* file name id */
        )
{
        EVP_PKEY *pkey;         /* private key */
        DSA     *dsa;           /* DSA parameters */
        BN_CTX  *ctx;           /* BN working space */
        BIGNUM  *b, *r, *k, *u, *v, *w; /* BN temp */
        FILE    *str;
        u_int   temp;
        const BIGNUM *p, *q, *g;
        BIGNUM *pub_key, *priv_key;
        
        /*
         * Generate DSA parameters for use as IFF parameters.
         */
        fprintf(stderr, "Generating IFF keys (%d bits)...\n",
            modulus2);
        dsa = genDsaParams(modulus2, _UC("IFF"));
        fprintf(stderr, "\n");
        if (dsa == NULL) {
                fprintf(stderr, "DSA generate parameters fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (NULL);
        }
        DSA_get0_pqg(dsa, &p, &q, &g);

        /*
         * Generate the private and public keys. The DSA parameters and
         * private key are distributed to the servers, while all except
         * the private key are distributed to the clients.
         */
        b = BN_new(); r = BN_new(); k = BN_new();
        u = BN_new(); v = BN_new(); w = BN_new(); ctx = BN_CTX_new();
        BN_rand(b, BN_num_bits(q), -1, 0);      /* a */
        BN_mod(b, b, q, ctx);
        BN_sub(v, q, b);
        BN_mod_exp(v, g, v, p, ctx); /* g^(q - b) mod p */
        BN_mod_exp(u, g, b, p, ctx);    /* g^b mod p */
        BN_mod_mul(u, u, v, p, ctx);
        temp = BN_is_one(u);
        fprintf(stderr,
            "Confirm g^(q - b) g^b = 1 mod p: %s\n", temp == 1 ?
            "yes" : "no");
        if (!temp) {
                BN_free(b); BN_free(r); BN_free(k);
                BN_free(u); BN_free(v); BN_free(w); BN_CTX_free(ctx);
                return (NULL);
        }
        pub_key = BN_dup(v);
        priv_key = BN_dup(b);
        DSA_set0_key(dsa, pub_key, priv_key);

        /*
         * Here is a trial round of the protocol. First, Alice rolls
         * random nonce r mod q and sends it to Bob. She needs only
         * q from parameters.
         */
        BN_rand(r, BN_num_bits(q), -1, 0);      /* r */
        BN_mod(r, r, q, ctx);

        /*
         * Bob rolls random nonce k mod q, computes y = k + b r mod q
         * and x = g^k mod p, then sends (y, x) to Alice. He needs
         * p, q and b from parameters and r from Alice.
         */
        BN_rand(k, BN_num_bits(q), -1, 0);      /* k, 0 < k < q  */
        BN_mod(k, k, q, ctx);
        BN_mod_mul(v, priv_key, r, q, ctx); /* b r mod q */
        BN_add(v, v, k);
        BN_mod(v, v, q, ctx);           /* y = k + b r mod q */
        BN_mod_exp(u, g, k, p, ctx);    /* x = g^k mod p */

        /*
         * Alice verifies x = g^y v^r to confirm that Bob has group key
         * b. She needs p, q, g from parameters, (y, x) from Bob and the
         * original r. We omit the detail here thatt only the hash of y
         * is sent.
         */
        BN_mod_exp(v, g, v, p, ctx); /* g^y mod p */
        BN_mod_exp(w, pub_key, r, p, ctx); /* v^r */
        BN_mod_mul(v, w, v, p, ctx);    /* product mod p */
        temp = BN_cmp(u, v);
        fprintf(stderr,
            "Confirm g^k = g^(k + b r) g^(q - b) r: %s\n", temp ==
            0 ? "yes" : "no");
        BN_free(b); BN_free(r); BN_free(k);
        BN_free(u); BN_free(v); BN_free(w); BN_CTX_free(ctx);
        if (temp != 0) {
                DSA_free(dsa);
                return (NULL);
        }

        /*
         * Write the IFF keys as an encrypted DSA private key encoded in
         * PEM.
         *
         * p    modulus p
         * q    modulus q
         * g    generator g
         * priv_key b
         * public_key v
         * kinv not used
         * r    not used
         */
        str = fheader("IFFkey", id, groupname);
        pkey = EVP_PKEY_new();
        EVP_PKEY_assign_DSA(pkey, dsa);
        PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
            passwd1);
        fclose(str);
        if (debug)
                DSA_print_fp(stderr, dsa, 0);
        return (pkey);
}


/*
 ***********************************************************************
 *                                                                     *
 * The following routines implement the Guillou-Quisquater (GQ)        *
 * identity scheme                                                     *
 *                                                                     *
 ***********************************************************************
 *
 * The Guillou-Quisquater (GQ) identity scheme is intended for use when
 * the certificate can be used to convey public parameters. The scheme
 * uses a X509v3 certificate extension field do convey the public key of
 * a private key known only to servers. There are two kinds of files:
 * encrypted server files that contain private and public values and
 * nonencrypted client files that contain only public values. New
 * generations of server files must be securely transmitted to all
 * servers of the group; client files can be distributed by any means.
 * The scheme is self contained and independent of new generations of
 * host keys and sign keys. The scheme is self contained and independent
 * of new generations of host keys and sign keys.
 *
 * The GQ parameters hide in a RSA cuckoo structure which uses the same
 * parameters. The values are used by an identity scheme based on RSA
 * cryptography and described in Stimson p. 300 (with errors). The 512-
 * bit public modulus is n = p q, where p and q are secret large primes.
 * The TA rolls private random group key b as RSA exponent. These values
 * are known to all group members.
 *
 * When rolling new certificates, a server recomputes the private and
 * public keys. The private key u is a random roll, while the public key
 * is the inverse obscured by the group key v = (u^-1)^b. These values
 * replace the private and public keys normally generated by the RSA
 * scheme. Alice challenges Bob to confirm identity using the protocol
 * described below.
 *
 * How it works
 *
 * The scheme goes like this. Both Alice and Bob have the same modulus n
 * and some random b as the group key. These values are computed and
 * distributed in advance via secret means, although only the group key
 * b is truly secret. Each has a private random private key u and public
 * key (u^-1)^b, although not necessarily the same ones. Bob and Alice
 * can regenerate the key pair from time to time without affecting
 * operations. The public key is conveyed on the certificate in an
 * extension field; the private key is never revealed.
 *
 * Alice rolls new random challenge r and sends to Bob in the GQ
 * request message. Bob rolls new random k, then computes y = k u^r mod
 * n and x = k^b mod n and sends (y, hash(x)) to Alice in the response
 * message. Besides making the response shorter, the hash makes it
 * effectivey impossible for an intruder to solve for b by observing
 * a number of these messages.
 * 
 * Alice receives the response and computes y^b v^r mod n. After a bit
 * of algebra, this simplifies to k^b. If the hash of this result
 * matches hash(x), Alice knows that Bob has the group key b. The signed
 * response binds this knowledge to Bob's private key and the public key
 * previously received in his certificate.
 */
/*
 * Generate Guillou-Quisquater (GQ) parameters file.
 */
EVP_PKEY *                      /* RSA cuckoo nest */
gen_gqkey(
        const char *id          /* file name id */
        )
{
        EVP_PKEY *pkey;         /* private key */
        RSA     *rsa;           /* RSA parameters */
        BN_CTX  *ctx;           /* BN working space */
        BIGNUM  *u, *v, *g, *k, *r, *y; /* BN temps */
        FILE    *str;
        u_int   temp;
        BIGNUM  *b;
        const BIGNUM    *n;
        
        /*
         * Generate RSA parameters for use as GQ parameters.
         */
        fprintf(stderr,
            "Generating GQ parameters (%d bits)...\n",
             modulus2);
        rsa = genRsaKeyPair(modulus2, _UC("GQ"));
        fprintf(stderr, "\n");
        if (rsa == NULL) {
                fprintf(stderr, "RSA generate keys fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (NULL);
        }
        RSA_get0_key(rsa, &n, NULL, NULL);
        u = BN_new(); v = BN_new(); g = BN_new();
        k = BN_new(); r = BN_new(); y = BN_new();
        b = BN_new();

        /*
         * Generate the group key b, which is saved in the e member of
         * the RSA structure. The group key is transmitted to each group
         * member encrypted by the member private key.
         */
        ctx = BN_CTX_new();
        BN_rand(b, BN_num_bits(n), -1, 0); /* b */
        BN_mod(b, b, n, ctx);

        /*
         * When generating his certificate, Bob rolls random private key
         * u, then computes inverse v = u^-1. 
         */
        BN_rand(u, BN_num_bits(n), -1, 0); /* u */
        BN_mod(u, u, n, ctx);
        BN_mod_inverse(v, u, n, ctx);   /* u^-1 mod n */
        BN_mod_mul(k, v, u, n, ctx);

        /*
         * Bob computes public key v = (u^-1)^b, which is saved in an
         * extension field on his certificate. We check that u^b v =
         * 1 mod n.
         */
        BN_mod_exp(v, v, b, n, ctx);
        BN_mod_exp(g, u, b, n, ctx); /* u^b */
        BN_mod_mul(g, g, v, n, ctx); /* u^b (u^-1)^b */
        temp = BN_is_one(g);
        fprintf(stderr,
            "Confirm u^b (u^-1)^b = 1 mod n: %s\n", temp ? "yes" :
            "no");
        if (!temp) {
                BN_free(u); BN_free(v);
                BN_free(g); BN_free(k); BN_free(r); BN_free(y);
                BN_CTX_free(ctx);
                RSA_free(rsa);
                return (NULL);
        }
        /* setting 'u' and 'v' into a RSA object takes over ownership.
         * Since we use these values again, we have to pass in dupes,
         * or we'll corrupt the program!
         */
        RSA_set0_factors(rsa, BN_dup(u), BN_dup(v));

        /*
         * Here is a trial run of the protocol. First, Alice rolls
         * random nonce r mod n and sends it to Bob. She needs only n
         * from parameters.
         */
        BN_rand(r, BN_num_bits(n), -1, 0);      /* r */
        BN_mod(r, r, n, ctx);

        /*
         * Bob rolls random nonce k mod n, computes y = k u^r mod n and
         * g = k^b mod n, then sends (y, g) to Alice. He needs n, u, b
         * from parameters and r from Alice. 
         */
        BN_rand(k, BN_num_bits(n), -1, 0);      /* k */
        BN_mod(k, k, n, ctx);
        BN_mod_exp(y, u, r, n, ctx);    /* u^r mod n */
        BN_mod_mul(y, k, y, n, ctx);    /* y = k u^r mod n */
        BN_mod_exp(g, k, b, n, ctx);    /* g = k^b mod n */

        /*
         * Alice verifies g = v^r y^b mod n to confirm that Bob has
         * private key u. She needs n, g from parameters, public key v =
         * (u^-1)^b from the certificate, (y, g) from Bob and the
         * original r. We omit the detaul here that only the hash of g
         * is sent.
         */
        BN_mod_exp(v, v, r, n, ctx);    /* v^r mod n */
        BN_mod_exp(y, y, b, n, ctx);    /* y^b mod n */
        BN_mod_mul(y, v, y, n, ctx);    /* v^r y^b mod n */
        temp = BN_cmp(y, g);
        fprintf(stderr, "Confirm g^k = v^r y^b mod n: %s\n", temp == 0 ?
            "yes" : "no");
        BN_CTX_free(ctx); BN_free(u); BN_free(v);
        BN_free(g); BN_free(k); BN_free(r); BN_free(y);
        if (temp != 0) {
                RSA_free(rsa);
                return (NULL);
        }

        /*
         * Write the GQ parameter file as an encrypted RSA private key
         * encoded in PEM.
         *
         * n    modulus n
         * e    group key b
         * d    not used
         * p    private key u
         * q    public key (u^-1)^b
         * dmp1 not used
         * dmq1 not used
         * iqmp not used
         */
        RSA_set0_key(rsa, NULL, b, BN_dup(BN_value_one()));
        RSA_set0_crt_params(rsa, BN_dup(BN_value_one()), BN_dup(BN_value_one()),
                BN_dup(BN_value_one()));
        str = fheader("GQkey", id, groupname);
        pkey = EVP_PKEY_new();
        EVP_PKEY_assign_RSA(pkey, rsa);
        PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
            passwd1);
        fclose(str);
        if (debug)
                RSA_print_fp(stderr, rsa, 0);
        return (pkey);
}


/*
 ***********************************************************************
 *                                                                     *
 * The following routines implement the Mu-Varadharajan (MV) identity  *
 * scheme                                                              *
 *                                                                     *
 ***********************************************************************
 *
 * The Mu-Varadharajan (MV) cryptosystem was originally intended when
 * servers broadcast messages to clients, but clients never send
 * messages to servers. There is one encryption key for the server and a
 * separate decryption key for each client. It operated something like a
 * pay-per-view satellite broadcasting system where the session key is
 * encrypted by the broadcaster and the decryption keys are held in a
 * tamperproof set-top box.
 *
 * The MV parameters and private encryption key hide in a DSA cuckoo
 * structure which uses the same parameters, but generated in a
 * different way. The values are used in an encryption scheme similar to
 * El Gamal cryptography and a polynomial formed from the expansion of
 * product terms (x - x[j]), as described in Mu, Y., and V.
 * Varadharajan: Robust and Secure Broadcasting, Proc. Indocrypt 2001,
 * 223-231. The paper has significant errors and serious omissions.
 *
 * Let q be the product of n distinct primes s1[j] (j = 1...n), where
 * each s1[j] has m significant bits. Let p be a prime p = 2 * q + 1, so
 * that q and each s1[j] divide p - 1 and p has M = n * m + 1
 * significant bits. Let g be a generator of Zp; that is, gcd(g, p - 1)
 * = 1 and g^q = 1 mod p. We do modular arithmetic over Zq and then
 * project into Zp* as exponents of g. Sometimes we have to compute an
 * inverse b^-1 of random b in Zq, but for that purpose we require
 * gcd(b, q) = 1. We expect M to be in the 500-bit range and n
 * relatively small, like 30. These are the parameters of the scheme and
 * they are expensive to compute.
 *
 * We set up an instance of the scheme as follows. A set of random
 * values x[j] mod q (j = 1...n), are generated as the zeros of a
 * polynomial of order n. The product terms (x - x[j]) are expanded to
 * form coefficients a[i] mod q (i = 0...n) in powers of x. These are
 * used as exponents of the generator g mod p to generate the private
 * encryption key A. The pair (gbar, ghat) of public server keys and the
 * pairs (xbar[j], xhat[j]) (j = 1...n) of private client keys are used
 * to construct the decryption keys. The devil is in the details.
 *
 * This routine generates a private server encryption file including the
 * private encryption key E and partial decryption keys gbar and ghat.
 * It then generates public client decryption files including the public
 * keys xbar[j] and xhat[j] for each client j. The partial decryption
 * files are used to compute the inverse of E. These values are suitably
 * blinded so secrets are not revealed.
 *
 * The distinguishing characteristic of this scheme is the capability to
 * revoke keys. Included in the calculation of E, gbar and ghat is the
 * product s = prod(s1[j]) (j = 1...n) above. If the factor s1[j] is
 * subsequently removed from the product and E, gbar and ghat
 * recomputed, the jth client will no longer be able to compute E^-1 and
 * thus unable to decrypt the messageblock.
 *
 * How it works
 *
 * The scheme goes like this. Bob has the server values (p, E, q,
 * gbar, ghat) and Alice has the client values (p, xbar, xhat).
 *
 * Alice rolls new random nonce r mod p and sends to Bob in the MV
 * request message. Bob rolls random nonce k mod q, encrypts y = r E^k
 * mod p and sends (y, gbar^k, ghat^k) to Alice.
 * 
 * Alice receives the response and computes the inverse (E^k)^-1 from
 * the partial decryption keys gbar^k, ghat^k, xbar and xhat. She then
 * decrypts y and verifies it matches the original r. The signed
 * response binds this knowledge to Bob's private key and the public key
 * previously received in his certificate.
 */
EVP_PKEY *                      /* DSA cuckoo nest */
gen_mvkey(
        const char *id,         /* file name id */
        EVP_PKEY **evpars       /* parameter list pointer */
        )
{
        EVP_PKEY *pkey, *pkey1; /* private keys */
        DSA     *dsa, *dsa2, *sdsa; /* DSA parameters */
        BN_CTX  *ctx;           /* BN working space */
        BIGNUM  *a[MVMAX];      /* polynomial coefficient vector */
        BIGNUM  *gs[MVMAX];     /* public key vector */
        BIGNUM  *s1[MVMAX];     /* private enabling keys */
        BIGNUM  *x[MVMAX];      /* polynomial zeros vector */
        BIGNUM  *xbar[MVMAX], *xhat[MVMAX]; /* private keys vector */
        BIGNUM  *b;             /* group key */
        BIGNUM  *b1;            /* inverse group key */
        BIGNUM  *s;             /* enabling key */
        BIGNUM  *biga;          /* master encryption key */
        BIGNUM  *bige;          /* session encryption key */
        BIGNUM  *gbar, *ghat;   /* public key */
        BIGNUM  *u, *v, *w;     /* BN scratch */
        BIGNUM  *p, *q, *g, *priv_key, *pub_key;
        int     i, j, n;
        FILE    *str;
        u_int   temp;

        /*
         * Generate MV parameters.
         *
         * The object is to generate a multiplicative group Zp* modulo a
         * prime p and a subset Zq mod q, where q is the product of n
         * distinct primes s1[j] (j = 1...n) and q divides p - 1. We
         * first generate n m-bit primes, where the product n m is in
         * the order of 512 bits. One or more of these may have to be
         * replaced later. As a practical matter, it is tough to find
         * more than 31 distinct primes for 512 bits or 61 primes for
         * 1024 bits. The latter can take several hundred iterations
         * and several minutes on a Sun Blade 1000.
         */
        n = nkeys;
        fprintf(stderr,
            "Generating MV parameters for %d keys (%d bits)...\n", n,
            modulus2 / n);
        ctx = BN_CTX_new(); u = BN_new(); v = BN_new(); w = BN_new();
        b = BN_new(); b1 = BN_new();
        dsa = DSA_new();
        p = BN_new(); q = BN_new(); g = BN_new();
        priv_key = BN_new(); pub_key = BN_new();
        temp = 0;
        for (j = 1; j <= n; j++) {
                s1[j] = BN_new();
                while (1) {
                        BN_generate_prime_ex(s1[j], modulus2 / n, 0,
                                             NULL, NULL, NULL);
                        for (i = 1; i < j; i++) {
                                if (BN_cmp(s1[i], s1[j]) == 0)
                                        break;
                        }
                        if (i == j)
                                break;
                        temp++;
                }
        }
        fprintf(stderr, "Birthday keys regenerated %d\n", temp);

        /*
         * Compute the modulus q as the product of the primes. Compute
         * the modulus p as 2 * q + 1 and test p for primality. If p
         * is composite, replace one of the primes with a new distinct
         * one and try again. Note that q will hardly be a secret since
         * we have to reveal p to servers, but not clients. However,
         * factoring q to find the primes should be adequately hard, as
         * this is the same problem considered hard in RSA. Question: is
         * it as hard to find n small prime factors totalling n bits as
         * it is to find two large prime factors totalling n bits?
         * Remember, the bad guy doesn't know n.
         */
        temp = 0;
        while (1) {
                BN_one(q);
                for (j = 1; j <= n; j++)
                        BN_mul(q, q, s1[j], ctx);
                BN_copy(p, q);
                BN_add(p, p, p);
                BN_add_word(p, 1);
                if (BN_is_prime_ex(p, BN_prime_checks, ctx, NULL))
                        break;

                temp++;
                j = temp % n + 1;
                while (1) {
                        BN_generate_prime_ex(u, modulus2 / n, 0,
                                             NULL, NULL, NULL);
                        for (i = 1; i <= n; i++) {
                                if (BN_cmp(u, s1[i]) == 0)
                                        break;
                        }
                        if (i > n)
                                break;
                }
                BN_copy(s1[j], u);
        }
        fprintf(stderr, "Defective keys regenerated %d\n", temp);

        /*
         * Compute the generator g using a random roll such that
         * gcd(g, p - 1) = 1 and g^q = 1. This is a generator of p, not
         * q. This may take several iterations.
         */
        BN_copy(v, p);
        BN_sub_word(v, 1);
        while (1) {
                BN_rand(g, BN_num_bits(p) - 1, 0, 0);
                BN_mod(g, g, p, ctx);
                BN_gcd(u, g, v, ctx);
                if (!BN_is_one(u))
                        continue;

                BN_mod_exp(u, g, q, p, ctx);
                if (BN_is_one(u))
                        break;
        }

        DSA_set0_pqg(dsa, p, q, g);

        /*
         * Setup is now complete. Roll random polynomial roots x[j]
         * (j = 1...n) for all j. While it may not be strictly
         * necessary, Make sure each root has no factors in common with
         * q.
         */
        fprintf(stderr,
            "Generating polynomial coefficients for %d roots (%d bits)\n",
            n, BN_num_bits(q));
        for (j = 1; j <= n; j++) {
                x[j] = BN_new();

                while (1) {
                        BN_rand(x[j], BN_num_bits(q), 0, 0);
                        BN_mod(x[j], x[j], q, ctx);
                        BN_gcd(u, x[j], q, ctx);
                        if (BN_is_one(u))
                                break;
                }
        }

        /*
         * Generate polynomial coefficients a[i] (i = 0...n) from the
         * expansion of root products (x - x[j]) mod q for all j. The
         * method is a present from Charlie Boncelet.
         */
        for (i = 0; i <= n; i++) {
                a[i] = BN_new();
                BN_one(a[i]);
        }
        for (j = 1; j <= n; j++) {
                BN_zero(w);
                for (i = 0; i < j; i++) {
                        BN_copy(u, q);
                        BN_mod_mul(v, a[i], x[j], q, ctx);
                        BN_sub(u, u, v);
                        BN_add(u, u, w);
                        BN_copy(w, a[i]);
                        BN_mod(a[i], u, q, ctx);
                }
        }

        /*
         * Generate gs[i] = g^a[i] mod p for all i and the generator g.
         */
        for (i = 0; i <= n; i++) {
                gs[i] = BN_new();
                BN_mod_exp(gs[i], g, a[i], p, ctx);
        }

        /*
         * Verify prod(gs[i]^(a[i] x[j]^i)) = 1 for all i, j. Note the
         * a[i] x[j]^i exponent is computed mod q, but the gs[i] is
         * computed mod p. also note the expression given in the paper
         * is incorrect.
         */
        temp = 1;
        for (j = 1; j <= n; j++) {
                BN_one(u);
                for (i = 0; i <= n; i++) {
                        BN_set_word(v, i);
                        BN_mod_exp(v, x[j], v, q, ctx);
                        BN_mod_mul(v, v, a[i], q, ctx);
                        BN_mod_exp(v, g, v, p, ctx);
                        BN_mod_mul(u, u, v, p, ctx);
                }
                if (!BN_is_one(u))
                        temp = 0;
        }
        fprintf(stderr,
            "Confirm prod(gs[i]^(x[j]^i)) = 1 for all i, j: %s\n", temp ?
            "yes" : "no");
        if (!temp) {
                return (NULL);
        }

        /*
         * Make private encryption key A. Keep it around for awhile,
         * since it is expensive to compute.
         */
        biga = BN_new();

        BN_one(biga);
        for (j = 1; j <= n; j++) {
                for (i = 0; i < n; i++) {
                        BN_set_word(v, i);
                        BN_mod_exp(v, x[j], v, q, ctx);
                        BN_mod_exp(v, gs[i], v, p, ctx);
                        BN_mod_mul(biga, biga, v, p, ctx);
                }
        }

        /*
         * Roll private random group key b mod q (0 < b < q), where
         * gcd(b, q) = 1 to guarantee b^-1 exists, then compute b^-1
         * mod q. If b is changed, the client keys must be recomputed.
         */
        while (1) {
                BN_rand(b, BN_num_bits(q), 0, 0);
                BN_mod(b, b, q, ctx);
                BN_gcd(u, b, q, ctx);
                if (BN_is_one(u))
                        break;
        }
        BN_mod_inverse(b1, b, q, ctx);

        /*
         * Make private client keys (xbar[j], xhat[j]) for all j. Note
         * that the keys for the jth client do not s1[j] or the product
         * s1[j]) (j = 1...n) which is q by construction.
         *
         * Compute the factor w such that w s1[j] = s1[j] for all j. The
         * easy way to do this is to compute (q + s1[j]) / s1[j].
         * Exercise for the student: prove the remainder is always zero.
         */
        for (j = 1; j <= n; j++) {
                xbar[j] = BN_new(); xhat[j] = BN_new();

                BN_add(w, q, s1[j]);
                BN_div(w, u, w, s1[j], ctx);
                BN_zero(xbar[j]);
                BN_set_word(v, n);
                for (i = 1; i <= n; i++) {
                        if (i == j)
                                continue;

                        BN_mod_exp(u, x[i], v, q, ctx);
                        BN_add(xbar[j], xbar[j], u);
                }
                BN_mod_mul(xbar[j], xbar[j], b1, q, ctx);
                BN_mod_exp(xhat[j], x[j], v, q, ctx);
                BN_mod_mul(xhat[j], xhat[j], w, q, ctx);
        }

        /*
         * We revoke client j by dividing q by s1[j]. The quotient
         * becomes the enabling key s. Note we always have to revoke
         * one key; otherwise, the plaintext and cryptotext would be
         * identical. For the present there are no provisions to revoke
         * additional keys, so we sail on with only token revocations.
         */
        s = BN_new();
        BN_copy(s, q);
        BN_div(s, u, s, s1[n], ctx);

        /*
         * For each combination of clients to be revoked, make private
         * encryption key E = A^s and partial decryption keys gbar = g^s
         * and ghat = g^(s b), all mod p. The servers use these keys to
         * compute the session encryption key and partial decryption
         * keys. These values must be regenerated if the enabling key is
         * changed.
         */
        bige = BN_new(); gbar = BN_new(); ghat = BN_new();
        BN_mod_exp(bige, biga, s, p, ctx);
        BN_mod_exp(gbar, g, s, p, ctx);
        BN_mod_mul(v, s, b, q, ctx);
        BN_mod_exp(ghat, g, v, p, ctx);
        
        /*
         * Notes: We produce the key media in three steps. The first
         * step is to generate the system parameters p, q, g, b, A and
         * the enabling keys s1[j]. Associated with each s1[j] are
         * parameters xbar[j] and xhat[j]. All of these parameters are
         * retained in a data structure protecteted by the trusted-agent
         * password. The p, xbar[j] and xhat[j] paremeters are
         * distributed to the j clients. When the client keys are to be
         * activated, the enabled keys are multipied together to form
         * the master enabling key s. This and the other parameters are
         * used to compute the server encryption key E and the partial
         * decryption keys gbar and ghat.
         *
         * In the identity exchange the client rolls random r and sends
         * it to the server. The server rolls random k, which is used
         * only once, then computes the session key E^k and partial
         * decryption keys gbar^k and ghat^k. The server sends the
         * encrypted r along with gbar^k and ghat^k to the client. The
         * client completes the decryption and verifies it matches r.
         */
        /*
         * Write the MV trusted-agent parameters and keys as a DSA
         * private key encoded in PEM.
         *
         * p    modulus p
         * q    modulus q
         * g    generator g
         * priv_key A mod p
         * pub_key b mod q
         * (remaining values are not used)
         */
        i = 0;
        str = fheader("MVta", "mvta", groupname);
        fprintf(stderr, "Generating MV trusted-authority keys\n");
        BN_copy(priv_key, biga);
        BN_copy(pub_key, b);
        DSA_set0_key(dsa, pub_key, priv_key);
        pkey = EVP_PKEY_new();
        EVP_PKEY_assign_DSA(pkey, dsa);
        PEM_write_PKCS8PrivateKey(str, pkey, cipher, NULL, 0, NULL,
            passwd1);
        evpars[i++] = pkey;
        if (debug)
                DSA_print_fp(stderr, dsa, 0);

        /*
         * Append the MV server parameters and keys as a DSA key encoded
         * in PEM.
         *
         * p    modulus p
         * q    modulus q (used only when generating k)
         * g    bige
         * priv_key gbar
         * pub_key ghat
         * (remaining values are not used)
         */
        fprintf(stderr, "Generating MV server keys\n");
        dsa2 = DSA_new();
        DSA_set0_pqg(dsa2, BN_dup(p), BN_dup(q), BN_dup(bige));
        DSA_set0_key(dsa2, BN_dup(ghat), BN_dup(gbar));
        pkey1 = EVP_PKEY_new();
        EVP_PKEY_assign_DSA(pkey1, dsa2);
        PEM_write_PKCS8PrivateKey(str, pkey1, cipher, NULL, 0, NULL,
            passwd1);
        evpars[i++] = pkey1;
        if (debug)
                DSA_print_fp(stderr, dsa2, 0);

        /*
         * Append the MV client parameters for each client j as DSA keys
         * encoded in PEM.
         *
         * p    modulus p
         * priv_key xbar[j] mod q
         * pub_key xhat[j] mod q
         * (remaining values are not used)
         */
        fprintf(stderr, "Generating %d MV client keys\n", n);
        for (j = 1; j <= n; j++) {
                sdsa = DSA_new();
                DSA_set0_pqg(sdsa, BN_dup(p), BN_dup(BN_value_one()),
                        BN_dup(BN_value_one()));
                DSA_set0_key(sdsa, BN_dup(xhat[j]), BN_dup(xbar[j]));
                pkey1 = EVP_PKEY_new();
                EVP_PKEY_set1_DSA(pkey1, sdsa);
                PEM_write_PKCS8PrivateKey(str, pkey1, cipher, NULL, 0,
                    NULL, passwd1);
                evpars[i++] = pkey1;
                if (debug)
                        DSA_print_fp(stderr, sdsa, 0);

                /*
                 * The product (gbar^k)^xbar[j] (ghat^k)^xhat[j] and E
                 * are inverses of each other. We check that the product
                 * is one for each client except the ones that have been
                 * revoked. 
                 */
                BN_mod_exp(v, gbar, xhat[j], p, ctx);
                BN_mod_exp(u, ghat, xbar[j], p, ctx);
                BN_mod_mul(u, u, v, p, ctx);
                BN_mod_mul(u, u, bige, p, ctx);
                if (!BN_is_one(u)) {
                        fprintf(stderr, "Revoke key %d\n", j);
                        continue;
                }
        }
        evpars[i++] = NULL;
        fclose(str);

        /*
         * Free the countries.
         */
        for (i = 0; i <= n; i++) {
                BN_free(a[i]); BN_free(gs[i]);
        }
        for (j = 1; j <= n; j++) {
                BN_free(x[j]); BN_free(xbar[j]); BN_free(xhat[j]);
                BN_free(s1[j]); 
        }
        return (pkey);
}


/*
 * Generate X509v3 certificate.
 *
 * The certificate consists of the version number, serial number,
 * validity interval, issuer name, subject name and public key. For a
 * self-signed certificate, the issuer name is the same as the subject
 * name and these items are signed using the subject private key. The
 * validity interval extends from the current time to the same time one
 * year hence. For NTP purposes, it is convenient to use the NTP seconds
 * of the current time as the serial number.
 */
int
x509    (
        EVP_PKEY *pkey,         /* signing key */
        const EVP_MD *md,       /* signature/digest scheme */
        char    *gqpub,         /* identity extension (hex string) */
        const char *exten,      /* private cert extension */
        char    *name           /* subject/issuer name */
        )
{
        X509    *cert;          /* X509 certificate */
        X509_NAME *subj;        /* distinguished (common) name */
        X509_EXTENSION *ex;     /* X509v3 extension */
        FILE    *str;           /* file handle */
        ASN1_INTEGER *serial;   /* serial number */
        const char *id;         /* digest/signature scheme name */
        char    pathbuf[MAXFILENAME + 1];

        /*
         * Generate X509 self-signed certificate.
         *
         * Set the certificate serial to the NTP seconds for grins. Set
         * the version to 3. Set the initial validity to the current
         * time and the finalvalidity one year hence.
         */
        id = OBJ_nid2sn(EVP_MD_pkey_type(md));
        fprintf(stderr, "Generating new certificate %s %s\n", name, id);
        cert = X509_new();
        X509_set_version(cert, 2L);
        serial = ASN1_INTEGER_new();
        ASN1_INTEGER_set(serial, (long)epoch + JAN_1970);
        X509_set_serialNumber(cert, serial);
        ASN1_INTEGER_free(serial);
        X509_time_adj(X509_getm_notBefore(cert), 0L, &epoch);
        X509_time_adj(X509_getm_notAfter(cert), lifetime * SECSPERDAY, &epoch);
        subj = X509_get_subject_name(cert);
        X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
            (u_char *)name, -1, -1, 0);
        subj = X509_get_issuer_name(cert);
        X509_NAME_add_entry_by_txt(subj, "commonName", MBSTRING_ASC,
            (u_char *)name, -1, -1, 0);
        if (!X509_set_pubkey(cert, pkey)) {
                fprintf(stderr, "Assign certificate signing key fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                X509_free(cert);
                return (0);
        }

        /*
         * Add X509v3 extensions if present. These represent the minimum
         * set defined in RFC3280 less the certificate_policy extension,
         * which is seriously obfuscated in OpenSSL.
         */
        /*
         * The basic_constraints extension CA:TRUE allows servers to
         * sign client certficitates.
         */
        fprintf(stderr, "%s: %s\n", LN_basic_constraints,
            BASIC_CONSTRAINTS);
        ex = X509V3_EXT_conf_nid(NULL, NULL, NID_basic_constraints,
            _UC(BASIC_CONSTRAINTS));
        if (!X509_add_ext(cert, ex, -1)) {
                fprintf(stderr, "Add extension field fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (0);
        }
        X509_EXTENSION_free(ex);

        /*
         * The key_usage extension designates the purposes the key can
         * be used for.
         */
        fprintf(stderr, "%s: %s\n", LN_key_usage, KEY_USAGE);
        ex = X509V3_EXT_conf_nid(NULL, NULL, NID_key_usage, _UC(KEY_USAGE));
        if (!X509_add_ext(cert, ex, -1)) {
                fprintf(stderr, "Add extension field fails\n%s\n",
                    ERR_error_string(ERR_get_error(), NULL));
                return (0);
        }
        X509_EXTENSION_free(ex);
        /*
         * The subject_key_identifier is used for the GQ public key.
         * This should not be controversial.
         */
        if (gqpub != NULL) {
                fprintf(stderr, "%s\n", LN_subject_key_identifier);
                ex = X509V3_EXT_conf_nid(NULL, NULL,
                    NID_subject_key_identifier, gqpub);
                if (!X509_add_ext(cert, ex, -1)) {
                        fprintf(stderr,
                            "Add extension field fails\n%s\n",
                            ERR_error_string(ERR_get_error(), NULL));
                        return (0);
                }
                X509_EXTENSION_free(ex);
        }

        /*
         * The extended key usage extension is used for special purpose
         * here. The semantics probably do not conform to the designer's
         * intent and will likely change in future.
         * 
         * "trustRoot" designates a root authority
         * "private" designates a private certificate
         */
        if (exten != NULL) {
                fprintf(stderr, "%s: %s\n", LN_ext_key_usage, exten);
                ex = X509V3_EXT_conf_nid(NULL, NULL,
                    NID_ext_key_usage, _UC(exten));
                if (!X509_add_ext(cert, ex, -1)) {
                        fprintf(stderr,
                            "Add extension field fails\n%s\n",
                            ERR_error_string(ERR_get_error(), NULL));
                        return (0);
                }
                X509_EXTENSION_free(ex);
        }

        /*
         * Sign and verify.
         */
        X509_sign(cert, pkey, md);
        if (X509_verify(cert, pkey) <= 0) {
                fprintf(stderr, "Verify %s certificate fails\n%s\n", id,
                    ERR_error_string(ERR_get_error(), NULL));
                X509_free(cert);
                return (0);
        }

        /*
         * Write the certificate encoded in PEM.
         */
        snprintf(pathbuf, sizeof(pathbuf), "%scert", id);
        str = fheader(pathbuf, "cert", hostname);
        PEM_write_X509(str, cert);
        fclose(str);
        if (debug)
                X509_print_fp(stderr, cert);
        X509_free(cert);
        return (1);
}

#if 0   /* asn2ntp is used only with commercial certificates */
/*
 * asn2ntp - convert ASN1_TIME time structure to NTP time
 */
u_long
asn2ntp (
        ASN1_TIME *asn1time     /* pointer to ASN1_TIME structure */
        )
{
        char    *v;             /* pointer to ASN1_TIME string */
        struct  tm tm;          /* time decode structure time */

        /*
         * Extract time string YYMMDDHHMMSSZ from ASN.1 time structure.
         * Note that the YY, MM, DD fields start with one, the HH, MM,
         * SS fiels start with zero and the Z character should be 'Z'
         * for UTC. Also note that years less than 50 map to years
         * greater than 100. Dontcha love ASN.1?
         */
        if (asn1time->length > 13)
                return (-1);
        v = (char *)asn1time->data;
        tm.tm_year = (v[0] - '0') * 10 + v[1] - '0';
        if (tm.tm_year < 50)
                tm.tm_year += 100;
        tm.tm_mon = (v[2] - '0') * 10 + v[3] - '0' - 1;
        tm.tm_mday = (v[4] - '0') * 10 + v[5] - '0';
        tm.tm_hour = (v[6] - '0') * 10 + v[7] - '0';
        tm.tm_min = (v[8] - '0') * 10 + v[9] - '0';
        tm.tm_sec = (v[10] - '0') * 10 + v[11] - '0';
        tm.tm_wday = 0;
        tm.tm_yday = 0;
        tm.tm_isdst = 0;
        return (mktime(&tm) + JAN_1970);
}
#endif

/*
 * Callback routine
 */
void
cb      (
        int     n1,             /* arg 1 */
        int     n2,             /* arg 2 */
        void    *chr            /* arg 3 */
        )
{
        switch (n1) {
        case 0:
                d0++;
                fprintf(stderr, "%s %d %d %lu\r", (char *)chr, n1, n2,
                    d0);
                break;
        case 1:
                d1++;
                fprintf(stderr, "%s\t\t%d %d %lu\r", (char *)chr, n1,
                    n2, d1);
                break;
        case 2:
                d2++;
                fprintf(stderr, "%s\t\t\t\t%d %d %lu\r", (char *)chr,
                    n1, n2, d2);
                break;
        case 3:
                d3++;
                fprintf(stderr, "%s\t\t\t\t\t\t%d %d %lu\r",
                    (char *)chr, n1, n2, d3);
                break;
        }
}


/*
 * Generate key
 */
EVP_PKEY *                      /* public/private key pair */
genkey(
        const char *type,       /* key type (RSA or DSA) */
        const char *id          /* file name id */
        )
{
        if (type == NULL)
                return (NULL);
        if (strcmp(type, "RSA") == 0)
                return (gen_rsa(id));

        else if (strcmp(type, "DSA") == 0)
                return (gen_dsa(id));

        fprintf(stderr, "Invalid %s key type %s\n", id, type);
        return (NULL);
}

static RSA*
genRsaKeyPair(
        int     bits,
        char *  what
        )
{
        RSA *           rsa = RSA_new();
        BN_GENCB *      gcb = BN_GENCB_new();
        BIGNUM *        bne = BN_new();
        
        if (gcb)
                BN_GENCB_set_old(gcb, cb, what);
        if (bne)
                BN_set_word(bne, 65537);
        if (!(rsa && gcb && bne && RSA_generate_key_ex(
                      rsa, bits, bne, gcb)))
        {
                RSA_free(rsa);
                rsa = NULL;
        }
        BN_GENCB_free(gcb);
        BN_free(bne);
        return rsa;
}

static DSA*
genDsaParams(
        int     bits,
        char *  what
        )
{
        
        DSA *           dsa = DSA_new();
        BN_GENCB *      gcb = BN_GENCB_new();
        u_char          seed[20];
        
        if (gcb)
                BN_GENCB_set_old(gcb, cb, what);
        RAND_bytes(seed, sizeof(seed));
        if (!(dsa && gcb && DSA_generate_parameters_ex(
                      dsa, bits, seed, sizeof(seed), NULL, NULL, gcb)))
        {
                DSA_free(dsa);
                dsa = NULL;
        }
        BN_GENCB_free(gcb);
        return dsa;
}

#endif  /* AUTOKEY */


/*
 * Generate file header and link
 */
FILE *
fheader (
        const char *file,       /* file name id */
        const char *ulink,      /* linkname */
        const char *owner       /* owner name */
        )
{
        FILE    *str;           /* file handle */
        char    linkname[MAXFILENAME]; /* link name */
        int     temp;
#ifdef HAVE_UMASK
        mode_t  orig_umask;
#endif
        
        snprintf(filename, sizeof(filename), "ntpkey_%s_%s.%u", file,
            owner, fstamp); 
#ifdef HAVE_UMASK
        orig_umask = umask( S_IWGRP | S_IRWXO );
        str = fopen(filename, "w");
        (void) umask(orig_umask);
#else
        str = fopen(filename, "w");
#endif
        if (str == NULL) {
                perror("Write");
                exit (-1);
        }
        if (strcmp(ulink, "md5") == 0) {
          strcpy(linkname,"ntp.keys");
        } else {
          snprintf(linkname, sizeof(linkname), "ntpkey_%s_%s", ulink,
                   hostname);
        }
        (void)remove(linkname);         /* The symlink() line below matters */
        temp = symlink(filename, linkname);
        if (temp < 0)
                perror(file);
        fprintf(stderr, "Generating new %s file and link\n", ulink);
        fprintf(stderr, "%s->%s\n", linkname, filename);
        fprintf(str, "# %s\n# %s\n", filename, ctime(&epoch));
        return (str);
}