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);
202 EVP_MD_CTX_init(&ctx->md);
210 static int ok_free(BIO *a)
212 if (a == NULL) return(0);
213 EVP_MD_CTX_cleanup(&((BIO_OK_CTX *)a->ptr)->md);
214 memset(a->ptr,0,sizeof(BIO_OK_CTX));
215 OPENSSL_free(a->ptr);
222 static int ok_read(BIO *b, char *out, int outl)
227 if (out == NULL) return(0);
228 ctx=(BIO_OK_CTX *)b->ptr;
230 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
235 /* copy clean bytes to output buffer */
238 i=ctx->buf_len-ctx->buf_off;
239 if (i > outl) i=outl;
240 memcpy(out,&(ctx->buf[ctx->buf_off]),i);
246 /* all clean bytes are out */
247 if (ctx->buf_len == ctx->buf_off)
251 /* copy start of the next block into proper place */
252 if(ctx->buf_len_save- ctx->buf_off_save > 0)
254 ctx->buf_len= ctx->buf_len_save- ctx->buf_off_save;
255 memmove(ctx->buf, &(ctx->buf[ctx->buf_off_save]),
266 /* output buffer full -- cancel */
267 if (outl == 0) break;
269 /* no clean bytes in buffer -- fill it */
270 n=IOBS- ctx->buf_len;
271 i=BIO_read(b->next_bio,&(ctx->buf[ctx->buf_len]),n);
273 if (i <= 0) break; /* nothing new */
277 /* no signature yet -- check if we got one */
278 if (ctx->sigio == 1) sig_in(b);
280 /* signature ok -- check if we got block */
281 if (ctx->sigio == 0) block_in(b);
283 /* invalid block -- cancel */
284 if (ctx->cont <= 0) break;
288 BIO_clear_retry_flags(b);
289 BIO_copy_next_retry(b);
293 static int ok_write(BIO *b, const char *in, int inl)
298 ctx=(BIO_OK_CTX *)b->ptr;
301 if ((ctx == NULL) || (b->next_bio == NULL) || (b->init == 0)) return(0);
303 if(ctx->sigio) sig_out(b);
306 BIO_clear_retry_flags(b);
307 n=ctx->buf_len-ctx->buf_off;
308 while (ctx->blockout && n > 0)
310 i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
313 BIO_copy_next_retry(b);
314 if(!BIO_should_retry(b))
322 /* at this point all pending data has been written */
324 if (ctx->buf_len == ctx->buf_off)
326 ctx->buf_len=OK_BLOCK_BLOCK;
330 if ((in == NULL) || (inl <= 0)) return(0);
332 n= (inl+ ctx->buf_len > OK_BLOCK_SIZE+ OK_BLOCK_BLOCK) ?
333 OK_BLOCK_SIZE+ OK_BLOCK_BLOCK- ctx->buf_len : inl;
335 memcpy((unsigned char *)(&(ctx->buf[ctx->buf_len])),(unsigned char *)in,n);
340 if(ctx->buf_len >= OK_BLOCK_SIZE+ OK_BLOCK_BLOCK)
346 BIO_clear_retry_flags(b);
347 BIO_copy_next_retry(b);
351 static long ok_ctrl(BIO *b, int cmd, long num, void *ptr)
372 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
374 case BIO_CTRL_EOF: /* More to read */
378 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
380 case BIO_CTRL_PENDING: /* More to read in buffer */
381 case BIO_CTRL_WPENDING: /* More to read in buffer */
382 ret=ctx->blockout ? ctx->buf_len-ctx->buf_off : 0;
384 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
387 /* do a final write */
388 if(ctx->blockout == 0)
391 while (ctx->blockout)
393 i=ok_write(b,NULL,0);
402 ctx->buf_off=ctx->buf_len=0;
405 /* Finally flush the underlying BIO */
406 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
408 case BIO_C_DO_STATE_MACHINE:
409 BIO_clear_retry_flags(b);
410 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
411 BIO_copy_next_retry(b);
418 EVP_DigestInit_ex(&ctx->md, md, NULL);
425 *ppmd=ctx->md.digest;
431 ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
437 static long ok_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
441 if (b->next_bio == NULL) return(0);
445 ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
451 static void longswap(void *_ptr, int len)
457 for(i= 0;i < len;i+= 4){
458 *((unsigned long *)&(ptr[i]))= swapem(*((unsigned long *)&(ptr[i])));
463 static void sig_out(BIO* b)
471 if(ctx->buf_len+ 2* md->digest->md_size > OK_BLOCK_SIZE) return;
473 EVP_DigestInit_ex(md, md->digest, NULL);
474 /* FIXME: there's absolutely no guarantee this makes any sense at all,
475 * particularly now EVP_MD_CTX has been restructured.
477 RAND_pseudo_bytes(md->md_data, md->digest->md_size);
478 memcpy(&(ctx->buf[ctx->buf_len]), md->md_data, md->digest->md_size);
479 longswap(&(ctx->buf[ctx->buf_len]), md->digest->md_size);
480 ctx->buf_len+= md->digest->md_size;
482 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
483 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
484 ctx->buf_len+= md->digest->md_size;
489 static void sig_in(BIO* b)
493 unsigned char tmp[EVP_MAX_MD_SIZE];
499 if(ctx->buf_len- ctx->buf_off < 2* md->digest->md_size) return;
501 EVP_DigestInit_ex(md, md->digest, NULL);
502 memcpy(md->md_data, &(ctx->buf[ctx->buf_off]), md->digest->md_size);
503 longswap(md->md_data, md->digest->md_size);
504 ctx->buf_off+= md->digest->md_size;
506 EVP_DigestUpdate(md, WELLKNOWN, strlen(WELLKNOWN));
507 EVP_DigestFinal_ex(md, tmp, NULL);
508 ret= memcmp(&(ctx->buf[ctx->buf_off]), tmp, md->digest->md_size) == 0;
509 ctx->buf_off+= md->digest->md_size;
513 if(ctx->buf_len != ctx->buf_off)
515 memmove(ctx->buf, &(ctx->buf[ctx->buf_off]), ctx->buf_len- ctx->buf_off);
517 ctx->buf_len-= ctx->buf_off;
526 static void block_out(BIO* b)
535 tl= ctx->buf_len- OK_BLOCK_BLOCK;
537 memcpy(ctx->buf, &tl, OK_BLOCK_BLOCK);
539 EVP_DigestUpdate(md, (unsigned char*) &(ctx->buf[OK_BLOCK_BLOCK]), tl);
540 EVP_DigestFinal_ex(md, &(ctx->buf[ctx->buf_len]), NULL);
541 ctx->buf_len+= md->digest->md_size;
545 static void block_in(BIO* b)
550 unsigned char tmp[EVP_MAX_MD_SIZE];
555 memcpy(&tl, ctx->buf, OK_BLOCK_BLOCK);
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;