1 /* crypto/evp/bio_ok.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
60 From: Arne Ansper <arne@cyber.ee>
64 I wrote function which took BIO* as argument, read data from it
65 and processed it. Then I wanted to store the input file in
66 encrypted form. OK I pushed BIO_f_cipher to the BIO stack
67 and everything was OK. BUT if user types wrong password
68 BIO_f_cipher outputs only garbage and my function crashes. Yes
69 I can and I should fix my function, but BIO_f_cipher is
70 easy way to add encryption support to many existing applications
71 and it's hard to debug and fix them all.
73 So I wanted another BIO which would catch the incorrect passwords and
74 file damages which cause garbage on BIO_f_cipher's output.
76 The easy way is to push the BIO_f_md and save the checksum at
77 the end of the file. However there are several problems with this
80 1) you must somehow separate checksum from actual data.
81 2) you need lot's of memory when reading the file, because you
82 must read to the end of the file and verify the checksum before
83 letting the application to read the data.
85 BIO_f_reliable tries to solve both problems, so that you can
86 read and write arbitrary long streams using only fixed amount
89 BIO_f_reliable splits data stream into blocks. Each block is prefixed
90 with it's length and suffixed with it's digest. So you need only
91 several Kbytes of memory to buffer single block before verifying
94 BIO_f_reliable goes further and adds several important capabilities:
96 1) the digest of the block is computed over the whole stream
97 -- so nobody can rearrange the blocks or remove or replace them.
99 2) to detect invalid passwords right at the start BIO_f_reliable
100 adds special prefix to the stream. In order to avoid known plain-text
101 attacks this prefix is generated as follows:
103 *) digest is initialized with random seed instead of
105 *) same seed is written to output
106 *) well-known text is then hashed and the output
107 of the digest is also written to output.
109 reader can now read the seed from stream, hash the same string
110 and then compare the digest output.
112 Bad things: BIO_f_reliable knows what's going on in EVP_Digest. I
113 initially wrote and tested this code on x86 machine and wrote the
114 digests out in machine-dependent order :( There are people using
115 this code and I cannot change this easily without making existing
116 data files unreadable.
123 #include "cryptlib.h"
124 #include <openssl/buffer.h>
125 #include <openssl/bio.h>
126 #include <openssl/evp.h>
127 #include <openssl/rand.h>
129 static int ok_write(BIO *h, const char *buf, int num);
130 static int ok_read(BIO *h, char *buf, int size);
131 static long ok_ctrl(BIO *h, int cmd, long arg1, void *arg2);
132 static int ok_new(BIO *h);
133 static int ok_free(BIO *data);
134 static long ok_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp);
136 static void sig_out(BIO *b);
137 static void sig_in(BIO *b);
138 static void block_out(BIO *b);
139 static void block_in(BIO *b);
140 #define OK_BLOCK_SIZE (1024*4)
141 #define OK_BLOCK_BLOCK 4
142 #define IOBS (OK_BLOCK_SIZE+ OK_BLOCK_BLOCK+ 3*EVP_MAX_MD_SIZE)
143 #define WELLKNOWN "The quick brown fox jumped over the lazy dog's back."
145 typedef struct ok_struct {
150 int cont; /* <= 0 when finished */
153 int blockout; /* output block is ready */
154 int sigio; /* must process signature */
155 unsigned char buf[IOBS];
158 static BIO_METHOD methods_ok = {
159 BIO_TYPE_CIPHER, "reliable",
170 BIO_METHOD *BIO_f_reliable(void)
172 return (&methods_ok);
175 static int ok_new(BIO *bi)
179 ctx = (BIO_OK_CTX *)OPENSSL_malloc(sizeof(BIO_OK_CTX));
185 ctx->buf_len_save = 0;
186 ctx->buf_off_save = 0;
192 EVP_MD_CTX_init(&ctx->md);
195 bi->ptr = (char *)ctx;
200 static int ok_free(BIO *a)
204 EVP_MD_CTX_cleanup(&((BIO_OK_CTX *)a->ptr)->md);
205 OPENSSL_cleanse(a->ptr, sizeof(BIO_OK_CTX));
206 OPENSSL_free(a->ptr);
213 static int ok_read(BIO *b, char *out, int outl)
220 ctx = (BIO_OK_CTX *)b->ptr;
222 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0))
227 /* copy clean bytes to output buffer */
229 i = ctx->buf_len - ctx->buf_off;
232 memcpy(out, &(ctx->buf[ctx->buf_off]), i);
238 /* all clean bytes are out */
239 if (ctx->buf_len == ctx->buf_off) {
243 * copy start of the next block into proper place
245 if (ctx->buf_len_save - ctx->buf_off_save > 0) {
246 ctx->buf_len = ctx->buf_len_save - ctx->buf_off_save;
247 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
256 /* output buffer full -- cancel */
260 /* no clean bytes in buffer -- fill it */
261 n = IOBS - ctx->buf_len;
262 i = BIO_read(b->next_bio, &(ctx->buf[ctx->buf_len]), n);
265 break; /* nothing new */
269 /* no signature yet -- check if we got one */
273 /* signature ok -- check if we got block */
277 /* invalid block -- cancel */
283 BIO_clear_retry_flags(b);
284 BIO_copy_next_retry(b);
288 static int ok_write(BIO *b, const char *in, int inl)
296 ctx = (BIO_OK_CTX *)b->ptr;
299 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0))
306 BIO_clear_retry_flags(b);
307 n = ctx->buf_len - ctx->buf_off;
308 while (ctx->blockout && n > 0) {
309 i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);
311 BIO_copy_next_retry(b);
312 if (!BIO_should_retry(b))
320 /* at this point all pending data has been written */
322 if (ctx->buf_len == ctx->buf_off) {
323 ctx->buf_len = OK_BLOCK_BLOCK;
327 if ((in == NULL) || (inl <= 0))
330 n = (inl + ctx->buf_len > OK_BLOCK_SIZE + OK_BLOCK_BLOCK) ?
331 (int)(OK_BLOCK_SIZE + OK_BLOCK_BLOCK - ctx->buf_len) : inl;
333 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),
334 (unsigned char *)in, n);
339 if (ctx->buf_len >= OK_BLOCK_SIZE + OK_BLOCK_BLOCK) {
344 BIO_clear_retry_flags(b);
345 BIO_copy_next_retry(b);
349 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
363 ctx->buf_len_save = 0;
364 ctx->buf_off_save = 0;
369 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
371 case BIO_CTRL_EOF: /* More to read */
375 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
377 case BIO_CTRL_PENDING: /* More to read in buffer */
378 case BIO_CTRL_WPENDING: /* More to read in buffer */
379 ret = ctx->blockout ? ctx->buf_len - ctx->buf_off : 0;
381 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
384 /* do a final write */
385 if (ctx->blockout == 0)
388 while (ctx->blockout) {
389 i = ok_write(b, NULL, 0);
397 ctx->buf_off = ctx->buf_len = 0;
398 ctx->cont = (int)ret;
400 /* Finally flush the underlying BIO */
401 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
403 case BIO_C_DO_STATE_MACHINE:
404 BIO_clear_retry_flags(b);
405 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
406 BIO_copy_next_retry(b);
409 ret = (long)ctx->cont;
413 EVP_DigestInit_ex(&ctx->md, md, NULL);
419 *ppmd = ctx->md.digest;
424 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
430 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
434 if (b->next_bio == NULL)
438 ret = BIO_callback_ctrl(b->next_bio, cmd, fp);
444 static void longswap(void *_ptr, size_t len)
453 if (is_endian.little) {
455 unsigned char *p = _ptr, c;
457 for (i = 0; i < len; i += 4) {
458 c = p[0], p[0] = p[3], p[3] = c;
459 c = p[1], p[1] = p[2], p[2] = c;
464 static void sig_out(BIO *b)
472 if (ctx->buf_len + 2 * md->digest->md_size > OK_BLOCK_SIZE)
475 EVP_DigestInit_ex(md, md->digest, NULL);
477 * FIXME: there's absolutely no guarantee this makes any sense at all,
478 * particularly now EVP_MD_CTX has been restructured.
480 RAND_pseudo_bytes(md->md_data, md->digest->md_size);
481 memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size);
482 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
483 ctx->buf_len += md->digest->md_size;
485 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
486 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
487 ctx->buf_len += md->digest->md_size;
492 static void sig_in(BIO *b)
496 unsigned char tmp[EVP_MAX_MD_SIZE];
502 if ((int)(ctx->buf_len - ctx->buf_off) < 2 * md->digest->md_size)
505 EVP_DigestInit_ex(md, md->digest, NULL);
506 memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size);
507 longswap(md->md_data, md->digest->md_size);
508 ctx->buf_off += md->digest->md_size;
510 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
511 EVP_DigestFinal_ex(md, tmp, NULL);
512 ret = memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
513 ctx->buf_off += md->digest->md_size;
516 if (ctx->buf_len != ctx->buf_off) {
517 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]),
518 ctx->buf_len - ctx->buf_off);
520 ctx->buf_len -= ctx->buf_off;
527 static void block_out(BIO *b)
536 tl = ctx->buf_len - OK_BLOCK_BLOCK;
537 ctx->buf[0] = (unsigned char)(tl >> 24);
538 ctx->buf[1] = (unsigned char)(tl >> 16);
539 ctx->buf[2] = (unsigned char)(tl >> 8);
540 ctx->buf[3] = (unsigned char)(tl);
541 EVP_DigestUpdate(md, (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl);
542 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
543 ctx->buf_len += md->digest->md_size;
547 static void block_in(BIO *b)
551 unsigned long tl = 0;
552 unsigned char tmp[EVP_MAX_MD_SIZE];
557 assert(sizeof(tl) >= OK_BLOCK_BLOCK); /* always true */
566 if (ctx->buf_len < tl + OK_BLOCK_BLOCK + md->digest->md_size)
569 EVP_DigestUpdate(md, (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl);
570 EVP_DigestFinal_ex(md, tmp, NULL);
571 if (memcmp(&(ctx->buf[tl + OK_BLOCK_BLOCK]), tmp, md->digest->md_size) ==
573 /* there might be parts from next block lurking around ! */
574 ctx->buf_off_save = tl + OK_BLOCK_BLOCK + md->digest->md_size;
575 ctx->buf_len_save = ctx->buf_len;
576 ctx->buf_off = OK_BLOCK_BLOCK;
577 ctx->buf_len = tl + OK_BLOCK_BLOCK;