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 ouput
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.
122 #include "cryptlib.h"
123 #include <openssl/buffer.h>
124 #include <openssl/bio.h>
125 #include <openssl/evp.h>
126 #include <openssl/rand.h>
128 static int ok_write(BIO *h, const char *buf, int num);
129 static int ok_read(BIO *h, char *buf, int size);
130 static long ok_ctrl(BIO *h, int cmd, long arg1, void *arg2);
131 static int ok_new(BIO *h);
132 static int ok_free(BIO *data);
133 static long ok_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp);
135 static void sig_out(BIO* b);
136 static void sig_in(BIO* b);
137 static void block_out(BIO* b);
138 static void block_in(BIO* b);
139 #define OK_BLOCK_SIZE (1024*4)
140 #define OK_BLOCK_BLOCK 4
141 #define IOBS (OK_BLOCK_SIZE+ OK_BLOCK_BLOCK+ 3*EVP_MAX_MD_SIZE)
142 #define WELLKNOWN "The quick brown fox jumped over the lazy dog's back."
146 ((unsigned long int)((((unsigned long int)(x) & 0x000000ffU) << 24) | \
147 (((unsigned long int)(x) & 0x0000ff00U) << 8) | \
148 (((unsigned long int)(x) & 0x00ff0000U) >> 8) | \
149 (((unsigned long int)(x) & 0xff000000U) >> 24)))
151 #define swapem(x) (x)
154 typedef struct ok_struct
160 int cont; /* <= 0 when finished */
163 int blockout; /* output block is ready */
164 int sigio; /* must process signature */
165 unsigned char buf[IOBS];
168 static BIO_METHOD methods_ok=
170 BIO_TYPE_CIPHER,"reliable",
181 BIO_METHOD *BIO_f_reliable(void)
186 static int ok_new(BIO *bi)
190 ctx=(BIO_OK_CTX *)OPENSSL_malloc(sizeof(BIO_OK_CTX));
191 if (ctx == NULL) return(0);
208 static int ok_free(BIO *a)
210 if (a == NULL) return(0);
211 memset(a->ptr,0,sizeof(BIO_OK_CTX));
212 OPENSSL_free(a->ptr);
219 static int ok_read(BIO *b, char *out, int outl)
224 if (out == NULL) return(0);
225 ctx=(BIO_OK_CTX *)b->ptr;
227 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
232 /* copy clean bytes to output buffer */
235 i=ctx->buf_len-ctx->buf_off;
236 if (i > outl) i=outl;
237 memcpy(out,&(ctx->buf[ctx->buf_off]),i);
243 /* all clean bytes are out */
244 if (ctx->buf_len == ctx->buf_off)
248 /* copy start of the next block into proper place */
249 if(ctx->buf_len_save- ctx->buf_off_save > 0)
251 ctx->buf_len= ctx->buf_len_save- ctx->buf_off_save;
252 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
263 /* output buffer full -- cancel */
264 if (outl == 0) break;
266 /* no clean bytes in buffer -- fill it */
267 n=IOBS- ctx->buf_len;
268 i=BIO_read(b->next_bio,&(ctx->buf[ctx->buf_len]),n);
270 if (i <= 0) break; /* nothing new */
274 /* no signature yet -- check if we got one */
275 if (ctx->sigio == 1) sig_in(b);
277 /* signature ok -- check if we got block */
278 if (ctx->sigio == 0) block_in(b);
280 /* invalid block -- cancel */
281 if (ctx->cont <= 0) break;
285 BIO_clear_retry_flags(b);
286 BIO_copy_next_retry(b);
290 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)) return(0);
300 if(ctx->sigio) sig_out(b);
303 BIO_clear_retry_flags(b);
304 n=ctx->buf_len-ctx->buf_off;
305 while (ctx->blockout && n > 0)
307 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)
323 ctx->buf_len=OK_BLOCK_BLOCK;
327 if ((in == NULL) || (inl <= 0)) return(0);
329 n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ?
330 OK_BLOCK_SIZE+ OK_BLOCK_BLOCK- ctx->buf_len : inl;
332 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n);
337 if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK)
343 BIO_clear_retry_flags(b);
344 BIO_copy_next_retry(b);
348 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
356 ctx=(BIO_OK_CTX *)b->ptr;
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)
390 i=ok_write(b,NULL,0);
399 ctx->buf_off=ctx->buf_len=0;
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);
415 EVP_DigestInit(&(ctx->md),md);
421 ppmd=(const EVP_MD **)ptr;
422 *ppmd=ctx->md.digest;
428 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
434 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
438 if (b->next_bio == NULL) return(0);
442 ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
448 static void longswap(void *_ptr, int len)
454 for(i= 0;i < len;i+= 4){
455 *((unsigned long *)&(ptr[i]))= swapem(*((unsigned long *)&(ptr[i])));
460 static void sig_out(BIO* b)
465 ctx=(BIO_OK_CTX *)b->ptr;
468 if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return;
470 EVP_DigestInit(md, md->digest);
471 RAND_pseudo_bytes(&(md->md.base[0]), md->digest->md_size);
472 memcpy(&(ctx->buf[ctx->buf_len]), &(md->md.base[0]), md->digest->md_size);
473 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
474 ctx->buf_len+= md->digest->md_size;
476 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
477 EVP_DigestFinal(md, &(ctx->buf[ctx->buf_len]), NULL);
478 ctx->buf_len+= md->digest->md_size;
483 static void sig_in(BIO* b)
487 unsigned char tmp[EVP_MAX_MD_SIZE];
490 ctx=(BIO_OK_CTX *)b->ptr;
493 if(ctx->buf_len- ctx->buf_off < 2* md->digest->md_size) return;
495 EVP_DigestInit(md, md->digest);
496 memcpy(&(md->md.base[0]), &(ctx->buf[ctx->buf_off]), md->digest->md_size);
497 longswap(&(md->md.base[0]), md->digest->md_size);
498 ctx->buf_off+= md->digest->md_size;
500 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
501 EVP_DigestFinal(md, tmp, NULL);
502 ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
503 ctx->buf_off+= md->digest->md_size;
507 if(ctx->buf_len != ctx->buf_off)
509 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off);
511 ctx->buf_len-= ctx->buf_off;
520 static void block_out(BIO* b)
526 ctx=(BIO_OK_CTX *)b->ptr;
529 tl= ctx->buf_len- OK_BLOCK_BLOCK;
531 memcpy(ctx->buf, &tl, OK_BLOCK_BLOCK);
533 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
534 EVP_DigestFinal(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];
546 ctx=(BIO_OK_CTX *)b->ptr;
549 memcpy(&tl, ctx->buf, OK_BLOCK_BLOCK);
551 if (ctx->buf_len < tl+ OK_BLOCK_BLOCK+ md->digest->md_size) return;
553 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
554 EVP_DigestFinal(md, tmp, NULL);
555 if(memcmp(&(ctx->buf[tl+ OK_BLOCK_BLOCK]), tmp, md->digest->md_size) == 0)
557 /* there might be parts from next block lurking around ! */
558 ctx->buf_off_save= tl+ OK_BLOCK_BLOCK+ md->digest->md_size;
559 ctx->buf_len_save= ctx->buf_len;
560 ctx->buf_off= OK_BLOCK_BLOCK;
561 ctx->buf_len= tl+ OK_BLOCK_BLOCK;