1 /* $OpenBSD: kex.h,v 1.114 2021/01/31 22:55:29 djm Exp $ */
4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include "crypto_api.h"
33 # include <openssl/bn.h>
34 # include <openssl/dh.h>
35 # include <openssl/ecdsa.h>
36 # ifdef OPENSSL_HAS_ECC
37 # include <openssl/ec.h>
38 # else /* OPENSSL_HAS_ECC */
40 # define EC_GROUP void
41 # define EC_POINT void
42 # endif /* OPENSSL_HAS_ECC */
43 #else /* WITH_OPENSSL */
47 # define EC_GROUP void
48 # define EC_POINT void
49 #endif /* WITH_OPENSSL */
51 #define KEX_COOKIE_LEN 16
53 #define KEX_DH1 "diffie-hellman-group1-sha1"
54 #define KEX_DH14_SHA1 "diffie-hellman-group14-sha1"
55 #define KEX_DH14_SHA256 "diffie-hellman-group14-sha256"
56 #define KEX_DH16_SHA512 "diffie-hellman-group16-sha512"
57 #define KEX_DH18_SHA512 "diffie-hellman-group18-sha512"
58 #define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1"
59 #define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256"
60 #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256"
61 #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384"
62 #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521"
63 #define KEX_CURVE25519_SHA256 "curve25519-sha256"
64 #define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org"
65 #define KEX_SNTRUP761X25519_SHA512 "sntrup761x25519-sha512@openssh.com"
68 /* pre-auth compression (COMP_ZLIB) is only supported in the client */
70 #define COMP_DELAYED 2
72 #define CURVE25519_SIZE 32
74 enum kex_init_proposals {
76 PROPOSAL_SERVER_HOST_KEY_ALGS,
77 PROPOSAL_ENC_ALGS_CTOS,
78 PROPOSAL_ENC_ALGS_STOC,
79 PROPOSAL_MAC_ALGS_CTOS,
80 PROPOSAL_MAC_ALGS_STOC,
81 PROPOSAL_COMP_ALGS_CTOS,
82 PROPOSAL_COMP_ALGS_STOC,
104 KEX_KEM_SNTRUP761X25519_SHA512,
108 #define KEX_INIT_SENT 0x0001
109 #define KEX_INITIAL 0x0002
113 const struct sshcipher *cipher;
135 struct newkeys *newkeys[MODE_MAX];
144 char *server_sig_algs;
148 struct sshbuf *client_version;
149 struct sshbuf *server_version;
150 struct sshbuf *session_id;
156 int (*verify_host_key)(struct sshkey *, struct ssh *);
157 struct sshkey *(*load_host_public_key)(int, int, struct ssh *);
158 struct sshkey *(*load_host_private_key)(int, int, struct ssh *);
159 int (*host_key_index)(struct sshkey *, int, struct ssh *);
160 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *,
161 u_char **, size_t *, const u_char *, size_t, const char *);
162 int (*kex[KEX_MAX])(struct ssh *);
163 /* kex specific state */
165 u_int min, max, nbits; /* GEX */
166 EC_KEY *ec_client_key; /* ECDH */
167 const EC_GROUP *ec_group; /* ECDH */
168 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */
169 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */
170 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */
171 struct sshbuf *client_pub;
174 int kex_names_valid(const char *);
175 char *kex_alg_list(char);
176 char *kex_names_cat(const char *, const char *);
177 int kex_assemble_names(char **, const char *, const char *);
179 int kex_exchange_identification(struct ssh *, int, const char *);
181 struct kex *kex_new(void);
182 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]);
183 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]);
184 void kex_free_newkeys(struct newkeys *);
185 void kex_free(struct kex *);
187 int kex_buf2prop(struct sshbuf *, int *, char ***);
188 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]);
189 void kex_prop_free(char **);
190 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **);
191 int kex_verify_host_key(struct ssh *, struct sshkey *);
193 int kex_send_kexinit(struct ssh *);
194 int kex_input_kexinit(int, u_int32_t, struct ssh *);
195 int kex_input_ext_info(int, u_int32_t, struct ssh *);
196 int kex_protocol_error(int, u_int32_t, struct ssh *);
197 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *);
198 int kex_send_newkeys(struct ssh *);
199 int kex_start_rekex(struct ssh *);
201 int kexgex_client(struct ssh *);
202 int kexgex_server(struct ssh *);
203 int kex_gen_client(struct ssh *);
204 int kex_gen_server(struct ssh *);
206 int kex_dh_keypair(struct kex *);
207 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
209 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **);
211 int kex_ecdh_keypair(struct kex *);
212 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
214 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **);
216 int kex_c25519_keypair(struct kex *);
217 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
219 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **);
221 int kex_kem_sntrup761x25519_keypair(struct kex *);
222 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *,
223 struct sshbuf **, struct sshbuf **);
224 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *,
227 int kex_dh_keygen(struct kex *);
228 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *);
230 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *,
231 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *,
233 const BIGNUM *, const BIGNUM *, const BIGNUM *,
234 const BIGNUM *, const u_char *, size_t,
237 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
238 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
239 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
240 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
241 const u_char pub[CURVE25519_SIZE], struct sshbuf *out)
242 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
243 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
244 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE],
245 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int)
246 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
247 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
249 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
250 void dump_digest(const char *, const u_char *, int);
253 #if !defined(WITH_OPENSSL) || !defined(OPENSSL_HAS_ECC)