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
151 int cont; /* <= 0 when finished */
154 int blockout; /* output block is ready */
155 int sigio; /* must process signature */
156 unsigned char buf[IOBS];
159 static BIO_METHOD methods_ok=
161 BIO_TYPE_CIPHER,"reliable",
172 BIO_METHOD *BIO_f_reliable(void)
177 static int ok_new(BIO *bi)
181 ctx=(BIO_OK_CTX *)OPENSSL_malloc(sizeof(BIO_OK_CTX));
182 if (ctx == NULL) return(0);
193 EVP_MD_CTX_init(&ctx->md);
201 static int ok_free(BIO *a)
203 if (a == NULL) return(0);
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)
218 if (out == NULL) return(0);
219 ctx=(BIO_OK_CTX *)b->ptr;
221 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
226 /* copy clean bytes to output buffer */
229 i=ctx->buf_len-ctx->buf_off;
230 if (i > outl) i=outl;
231 memcpy(out,&(ctx->buf[ctx->buf_off]),i);
237 /* all clean bytes are out */
238 if (ctx->buf_len == ctx->buf_off)
242 /* copy start of the next block into proper place */
243 if(ctx->buf_len_save- ctx->buf_off_save > 0)
245 ctx->buf_len= ctx->buf_len_save- ctx->buf_off_save;
246 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
257 /* output buffer full -- cancel */
258 if (outl == 0) break;
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);
264 if (i <= 0) break; /* nothing new */
268 /* no signature yet -- check if we got one */
269 if (ctx->sigio == 1) sig_in(b);
271 /* signature ok -- check if we got block */
272 if (ctx->sigio == 0) block_in(b);
274 /* invalid block -- cancel */
275 if (ctx->cont <= 0) break;
279 BIO_clear_retry_flags(b);
280 BIO_copy_next_retry(b);
284 static int ok_write(BIO *b, const char *in, int inl)
289 ctx=(BIO_OK_CTX *)b->ptr;
292 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
294 if(ctx->sigio) sig_out(b);
297 BIO_clear_retry_flags(b);
298 n=ctx->buf_len-ctx->buf_off;
299 while (ctx->blockout && n > 0)
301 i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
304 BIO_copy_next_retry(b);
305 if(!BIO_should_retry(b))
313 /* at this point all pending data has been written */
315 if (ctx->buf_len == ctx->buf_off)
317 ctx->buf_len=OK_BLOCK_BLOCK;
321 if ((in == NULL) || (inl <= 0)) return(0);
323 n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ?
324 OK_BLOCK_SIZE+ OK_BLOCK_BLOCK- ctx->buf_len : inl;
326 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n);
331 if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK)
337 BIO_clear_retry_flags(b);
338 BIO_copy_next_retry(b);
342 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
363 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
365 case BIO_CTRL_EOF: /* More to read */
369 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
371 case BIO_CTRL_PENDING: /* More to read in buffer */
372 case BIO_CTRL_WPENDING: /* More to read in buffer */
373 ret=ctx->blockout ? ctx->buf_len-ctx->buf_off : 0;
375 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
378 /* do a final write */
379 if(ctx->blockout == 0)
382 while (ctx->blockout)
384 i=ok_write(b,NULL,0);
393 ctx->buf_off=ctx->buf_len=0;
396 /* Finally flush the underlying BIO */
397 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
399 case BIO_C_DO_STATE_MACHINE:
400 BIO_clear_retry_flags(b);
401 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
402 BIO_copy_next_retry(b);
409 EVP_DigestInit_ex(&ctx->md, md, NULL);
416 *ppmd=ctx->md.digest;
422 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
428 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
432 if (b->next_bio == NULL) return(0);
436 ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
442 static void longswap(void *_ptr, size_t len)
443 { const union { long one; char little; } is_endian = {1};
445 if (is_endian.little) {
447 unsigned char *p=_ptr,c;
449 for(i= 0;i < len;i+= 4) {
450 c=p[0],p[0]=p[3],p[3]=c;
451 c=p[1],p[1]=p[2],p[2]=c;
456 static void sig_out(BIO* b)
464 if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return;
466 EVP_DigestInit_ex(md, md->digest, NULL);
467 /* FIXME: there's absolutely no guarantee this makes any sense at all,
468 * particularly now EVP_MD_CTX has been restructured.
470 RAND_pseudo_bytes(md->md_data, md->digest->md_size);
471 memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size);
472 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
473 ctx->buf_len+= md->digest->md_size;
475 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
476 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
477 ctx->buf_len+= md->digest->md_size;
482 static void sig_in(BIO* b)
486 unsigned char tmp[EVP_MAX_MD_SIZE];
492 if(ctx->buf_len- ctx->buf_off < 2* md->digest->md_size) return;
494 EVP_DigestInit_ex(md, md->digest, NULL);
495 memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size);
496 longswap(md->md_data, md->digest->md_size);
497 ctx->buf_off+= md->digest->md_size;
499 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
500 EVP_DigestFinal_ex(md, tmp, NULL);
501 ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
502 ctx->buf_off+= md->digest->md_size;
506 if(ctx->buf_len != ctx->buf_off)
508 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off);
510 ctx->buf_len-= ctx->buf_off;
519 static void block_out(BIO* b)
528 tl= ctx->buf_len- OK_BLOCK_BLOCK;
529 ctx->buf[0]=(unsigned char)(tl>>24);
530 ctx->buf[1]=(unsigned char)(tl>>16);
531 ctx->buf[2]=(unsigned char)(tl>>8);
532 ctx->buf[3]=(unsigned char)(tl);
533 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
534 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
535 ctx->buf_len+= md->digest->md_size;
539 static void block_in(BIO* b)
544 unsigned char tmp[EVP_MAX_MD_SIZE];
549 assert(sizeof(tl)>=OK_BLOCK_BLOCK); /* always true */
550 tl =ctx->buf[0]; tl<<=8;
551 tl|=ctx->buf[1]; tl<<=8;
552 tl|=ctx->buf[2]; tl<<=8;
555 if (ctx->buf_len < tl+ OK_BLOCK_BLOCK+ md->digest->md_size) return;
557 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
558 EVP_DigestFinal_ex(md, tmp, NULL);
559 if(memcmp(&(ctx->buf[tl+ OK_BLOCK_BLOCK]), tmp, md->digest->md_size) == 0)
561 /* there might be parts from next block lurking around ! */
562 ctx->buf_off_save= tl+ OK_BLOCK_BLOCK+ md->digest->md_size;
563 ctx->buf_len_save= ctx->buf_len;
564 ctx->buf_off= OK_BLOCK_BLOCK;
565 ctx->buf_len= tl+ OK_BLOCK_BLOCK;