1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
59 From: Arne Ansper <arne@cyber.ee>
63 I wrote function which took BIO* as argument, read data from it
64 and processed it. Then I wanted to store the input file in
65 encrypted form. OK I pushed BIO_f_cipher to the BIO stack
66 and everything was OK. BUT if user types wrong password
67 BIO_f_cipher outputs only garbage and my function crashes. Yes
68 I can and I should fix my function, but BIO_f_cipher is
69 easy way to add encryption support to many existing applications
70 and it's hard to debug and fix them all.
72 So I wanted another BIO which would catch the incorrect passwords and
73 file damages which cause garbage on BIO_f_cipher's output.
75 The easy way is to push the BIO_f_md and save the checksum at
76 the end of the file. However there are several problems with this
79 1) you must somehow separate checksum from actual data.
80 2) you need lot's of memory when reading the file, because you
81 must read to the end of the file and verify the checksum before
82 letting the application to read the data.
84 BIO_f_reliable tries to solve both problems, so that you can
85 read and write arbitrary long streams using only fixed amount
88 BIO_f_reliable splits data stream into blocks. Each block is prefixed
89 with it's length and suffixed with it's digest. So you need only
90 several Kbytes of memory to buffer single block before verifying
93 BIO_f_reliable goes further and adds several important capabilities:
95 1) the digest of the block is computed over the whole stream
96 -- so nobody can rearrange the blocks or remove or replace them.
98 2) to detect invalid passwords right at the start BIO_f_reliable
99 adds special prefix to the stream. In order to avoid known plain-text
100 attacks this prefix is generated as follows:
102 *) digest is initialized with random seed instead of
104 *) same seed is written to output
105 *) well-known text is then hashed and the output
106 of the digest is also written to output.
108 reader can now read the seed from stream, hash the same string
109 and then compare the digest output.
111 Bad things: BIO_f_reliable knows what's going on in EVP_Digest. I
112 initially wrote and tested this code on x86 machine and wrote the
113 digests out in machine-dependent order :( There are people using
114 this code and I cannot change this easily without making existing
115 data files unreadable.
122 #include "internal/cryptlib.h"
123 #include <openssl/buffer.h>
124 #include <openssl/bio.h>
125 #include <openssl/evp.h>
126 #include <openssl/rand.h>
127 #include "internal/evp_int.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 __owur int sig_out(BIO *b);
137 static __owur int sig_in(BIO *b);
138 static __owur int block_out(BIO *b);
139 static __owur int 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 = OPENSSL_zalloc(sizeof(*ctx));
185 ctx->md = EVP_MD_CTX_new();
187 bi->ptr = (char *)ctx;
192 static int ok_free(BIO *a)
196 EVP_MD_CTX_free(((BIO_OK_CTX *)a->ptr)->md);
197 OPENSSL_clear_free(a->ptr, sizeof(BIO_OK_CTX));
204 static int ok_read(BIO *b, char *out, int outl)
211 ctx = (BIO_OK_CTX *)b->ptr;
213 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0))
218 /* copy clean bytes to output buffer */
220 i = ctx->buf_len - ctx->buf_off;
223 memcpy(out, &(ctx->buf[ctx->buf_off]), i);
229 /* all clean bytes are out */
230 if (ctx->buf_len == ctx->buf_off) {
234 * copy start of the next block into proper place
236 if (ctx->buf_len_save - ctx->buf_off_save > 0) {
237 ctx->buf_len = ctx->buf_len_save - ctx->buf_off_save;
238 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
247 /* output buffer full -- cancel */
251 /* no clean bytes in buffer -- fill it */
252 n = IOBS - ctx->buf_len;
253 i = BIO_read(b->next_bio, &(ctx->buf[ctx->buf_len]), n);
256 break; /* nothing new */
260 /* no signature yet -- check if we got one */
261 if (ctx->sigio == 1) {
263 BIO_clear_retry_flags(b);
268 /* signature ok -- check if we got block */
269 if (ctx->sigio == 0) {
271 BIO_clear_retry_flags(b);
276 /* invalid block -- cancel */
282 BIO_clear_retry_flags(b);
283 BIO_copy_next_retry(b);
287 static int ok_write(BIO *b, const char *in, int inl)
295 ctx = (BIO_OK_CTX *)b->ptr;
298 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0))
301 if (ctx->sigio && !sig_out(b))
305 BIO_clear_retry_flags(b);
306 n = ctx->buf_len - ctx->buf_off;
307 while (ctx->blockout && n > 0) {
308 i = BIO_write(b->next_bio, &(ctx->buf[ctx->buf_off]), n);
310 BIO_copy_next_retry(b);
311 if (!BIO_should_retry(b))
319 /* at this point all pending data has been written */
321 if (ctx->buf_len == ctx->buf_off) {
322 ctx->buf_len = OK_BLOCK_BLOCK;
326 if ((in == NULL) || (inl <= 0))
329 n = (inl + ctx->buf_len > OK_BLOCK_SIZE + OK_BLOCK_BLOCK) ?
330 (int)(OK_BLOCK_SIZE + OK_BLOCK_BLOCK - ctx->buf_len) : inl;
332 memcpy(&ctx->buf[ctx->buf_len], in, n);
337 if (ctx->buf_len >= OK_BLOCK_SIZE + OK_BLOCK_BLOCK) {
339 BIO_clear_retry_flags(b);
345 BIO_clear_retry_flags(b);
346 BIO_copy_next_retry(b);
350 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
364 ctx->buf_len_save = 0;
365 ctx->buf_off_save = 0;
370 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
372 case BIO_CTRL_EOF: /* More to read */
376 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
378 case BIO_CTRL_PENDING: /* More to read in buffer */
379 case BIO_CTRL_WPENDING: /* More to read in buffer */
380 ret = ctx->blockout ? ctx->buf_len - ctx->buf_off : 0;
382 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
385 /* do a final write */
386 if (ctx->blockout == 0)
390 while (ctx->blockout) {
391 i = ok_write(b, NULL, 0);
399 ctx->buf_off = ctx->buf_len = 0;
400 ctx->cont = (int)ret;
402 /* Finally flush the underlying BIO */
403 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
405 case BIO_C_DO_STATE_MACHINE:
406 BIO_clear_retry_flags(b);
407 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
408 BIO_copy_next_retry(b);
411 ret = (long)ctx->cont;
415 if (!EVP_DigestInit_ex(ctx->md, md, NULL))
422 *ppmd = EVP_MD_CTX_md(ctx->md);
427 ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
433 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
437 if (b->next_bio == NULL)
441 ret = BIO_callback_ctrl(b->next_bio, cmd, fp);
447 static void longswap(void *_ptr, size_t len)
456 if (is_endian.little) {
458 unsigned char *p = _ptr, c;
460 for (i = 0; i < len; i += 4) {
461 c = p[0], p[0] = p[3], p[3] = c;
462 c = p[1], p[1] = p[2], p[2] = c;
467 static int sig_out(BIO *b)
471 const EVP_MD *digest;
477 digest = EVP_MD_CTX_md(md);
478 md_size = EVP_MD_size(digest);
479 md_data = EVP_MD_CTX_md_data(md);
481 if (ctx->buf_len + 2 * md_size > OK_BLOCK_SIZE)
484 if (!EVP_DigestInit_ex(md, digest, NULL))
487 * FIXME: there's absolutely no guarantee this makes any sense at all,
488 * particularly now EVP_MD_CTX has been restructured.
490 if (RAND_bytes(md_data, md_size) <= 0)
492 memcpy(&(ctx->buf[ctx->buf_len]), md_data, md_size);
493 longswap(&(ctx->buf[ctx->buf_len]), md_size);
494 ctx->buf_len += md_size;
496 if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
498 if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
500 ctx->buf_len += md_size;
505 BIO_clear_retry_flags(b);
509 static int sig_in(BIO *b)
513 unsigned char tmp[EVP_MAX_MD_SIZE];
515 const EVP_MD *digest;
521 digest = EVP_MD_CTX_md(md);
522 md_size = EVP_MD_size(digest);
523 md_data = EVP_MD_CTX_md_data(md);
525 if ((int)(ctx->buf_len - ctx->buf_off) < 2 * md_size)
528 if (!EVP_DigestInit_ex(md, digest, NULL))
530 memcpy(md_data, &(ctx->buf[ctx->buf_off]), md_size);
531 longswap(md_data, md_size);
532 ctx->buf_off += md_size;
534 if (!EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN)))
536 if (!EVP_DigestFinal_ex(md, tmp, NULL))
538 ret = memcmp(&(ctx->buf[ctx->buf_off]), tmp, md_size) == 0;
539 ctx->buf_off += md_size;
542 if (ctx->buf_len != ctx->buf_off) {
543 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]),
544 ctx->buf_len - ctx->buf_off);
546 ctx->buf_len -= ctx->buf_off;
553 BIO_clear_retry_flags(b);
557 static int block_out(BIO *b)
562 const EVP_MD *digest;
567 digest = EVP_MD_CTX_md(md);
568 md_size = EVP_MD_size(digest);
570 tl = ctx->buf_len - OK_BLOCK_BLOCK;
571 ctx->buf[0] = (unsigned char)(tl >> 24);
572 ctx->buf[1] = (unsigned char)(tl >> 16);
573 ctx->buf[2] = (unsigned char)(tl >> 8);
574 ctx->buf[3] = (unsigned char)(tl);
575 if (!EVP_DigestUpdate(md,
576 (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl))
578 if (!EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL))
580 ctx->buf_len += md_size;
584 BIO_clear_retry_flags(b);
588 static int block_in(BIO *b)
592 unsigned long tl = 0;
593 unsigned char tmp[EVP_MAX_MD_SIZE];
598 md_size = EVP_MD_size(EVP_MD_CTX_md(md));
600 assert(sizeof(tl) >= OK_BLOCK_BLOCK); /* always true */
609 if (ctx->buf_len < tl + OK_BLOCK_BLOCK + md_size)
612 if (!EVP_DigestUpdate(md,
613 (unsigned char *)&(ctx->buf[OK_BLOCK_BLOCK]), tl))
615 if (!EVP_DigestFinal_ex(md, tmp, NULL))
617 if (memcmp(&(ctx->buf[tl + OK_BLOCK_BLOCK]), tmp, md_size) == 0) {
618 /* there might be parts from next block lurking around ! */
619 ctx->buf_off_save = tl + OK_BLOCK_BLOCK + md_size;
620 ctx->buf_len_save = ctx->buf_len;
621 ctx->buf_off = OK_BLOCK_BLOCK;
622 ctx->buf_len = tl + OK_BLOCK_BLOCK;
629 BIO_clear_retry_flags(b);