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 if (inl <= 0) return inl;
291 ctx=(BIO_OK_CTX *)b->ptr;
294 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
296 if(ctx->sigio) sig_out(b);
299 BIO_clear_retry_flags(b);
300 n=ctx->buf_len-ctx->buf_off;
301 while (ctx->blockout && n > 0)
303 i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
306 BIO_copy_next_retry(b);
307 if(!BIO_should_retry(b))
315 /* at this point all pending data has been written */
317 if (ctx->buf_len == ctx->buf_off)
319 ctx->buf_len=OK_BLOCK_BLOCK;
323 if ((in == NULL) || (inl <= 0)) return(0);
325 n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ?
326 (int)(OK_BLOCK_SIZE+OK_BLOCK_BLOCK-ctx->buf_len) : inl;
328 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n);
333 if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK)
339 BIO_clear_retry_flags(b);
340 BIO_copy_next_retry(b);
344 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
365 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
367 case BIO_CTRL_EOF: /* More to read */
371 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
373 case BIO_CTRL_PENDING: /* More to read in buffer */
374 case BIO_CTRL_WPENDING: /* More to read in buffer */
375 ret=ctx->blockout ? ctx->buf_len-ctx->buf_off : 0;
377 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
380 /* do a final write */
381 if(ctx->blockout == 0)
384 while (ctx->blockout)
386 i=ok_write(b,NULL,0);
395 ctx->buf_off=ctx->buf_len=0;
398 /* Finally flush the underlying BIO */
399 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
401 case BIO_C_DO_STATE_MACHINE:
402 BIO_clear_retry_flags(b);
403 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
404 BIO_copy_next_retry(b);
411 EVP_DigestInit_ex(&ctx->md, md, NULL);
418 *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) return(0);
438 ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
444 static void longswap(void *_ptr, size_t len)
445 { const union { long one; char little; } is_endian = {1};
447 if (is_endian.little) {
449 unsigned char *p=_ptr,c;
451 for(i= 0;i < len;i+= 4) {
452 c=p[0],p[0]=p[3],p[3]=c;
453 c=p[1],p[1]=p[2],p[2]=c;
458 static void sig_out(BIO* b)
466 if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return;
468 EVP_DigestInit_ex(md, md->digest, NULL);
469 /* FIXME: there's absolutely no guarantee this makes any sense at all,
470 * particularly now EVP_MD_CTX has been restructured.
472 RAND_pseudo_bytes(md->md_data, md->digest->md_size);
473 memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size);
474 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
475 ctx->buf_len+= md->digest->md_size;
477 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
478 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
479 ctx->buf_len+= md->digest->md_size;
484 static void sig_in(BIO* b)
488 unsigned char tmp[EVP_MAX_MD_SIZE];
494 if((int)(ctx->buf_len-ctx->buf_off) < 2*md->digest->md_size) return;
496 EVP_DigestInit_ex(md, md->digest, NULL);
497 memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size);
498 longswap(md->md_data, md->digest->md_size);
499 ctx->buf_off+= md->digest->md_size;
501 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
502 EVP_DigestFinal_ex(md, tmp, NULL);
503 ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
504 ctx->buf_off+= md->digest->md_size;
508 if(ctx->buf_len != ctx->buf_off)
510 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off);
512 ctx->buf_len-= ctx->buf_off;
521 static void block_out(BIO* b)
530 tl= ctx->buf_len- OK_BLOCK_BLOCK;
531 ctx->buf[0]=(unsigned char)(tl>>24);
532 ctx->buf[1]=(unsigned char)(tl>>16);
533 ctx->buf[2]=(unsigned char)(tl>>8);
534 ctx->buf[3]=(unsigned char)(tl);
535 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
536 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
537 ctx->buf_len+= md->digest->md_size;
541 static void block_in(BIO* b)
546 unsigned char tmp[EVP_MAX_MD_SIZE];
551 assert(sizeof(tl)>=OK_BLOCK_BLOCK); /* always true */
552 tl =ctx->buf[0]; tl<<=8;
553 tl|=ctx->buf[1]; tl<<=8;
554 tl|=ctx->buf[2]; tl<<=8;
557 if (ctx->buf_len < tl+ OK_BLOCK_BLOCK+ md->digest->md_size) return;
559 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
560 EVP_DigestFinal_ex(md, tmp, NULL);
561 if(memcmp(&(ctx->buf[tl+ OK_BLOCK_BLOCK]), tmp, md->digest->md_size) == 0)
563 /* there might be parts from next block lurking around ! */
564 ctx->buf_off_save= tl+ OK_BLOCK_BLOCK+ md->digest->md_size;
565 ctx->buf_len_save= ctx->buf_len;
566 ctx->buf_off= OK_BLOCK_BLOCK;
567 ctx->buf_len= tl+ OK_BLOCK_BLOCK;