File: ccrypt.c

package info (click to toggle)
ccrypt 1.7-11
  • links: PTS
  • area: main
  • in suites: lenny, squeeze
  • size: 968 kB
  • ctags: 390
  • sloc: ansic: 3,833; sh: 1,113; lisp: 650; makefile: 111; sed: 19
file content (470 lines) | stat: -rw-r--r-- 10,781 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
/* Copyright (C) 2000-2004 Peter Selinger.
   This file is part of ccrypt. It is free software and it is covered
   by the GNU general public license. See the file COPYING for details. */

/* ccrypt.c: high-level functions for accessing ccryptlib */
/* $Id: ccrypt.c,v 1.10 2003/08/25 18:06:19 selinger Exp $ */

/* ccrypt implements a stream cipher based on the block cipher
   Rijndael, the candidate for the AES standard. */

#define _FILE_OFFSET_BITS 64  /* turn off 2GB limit on file size */

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

#include "main.h"
#include "ccryptlib.h"
#include "unixcryptlib.h"

/* heuristically, the fastest inbufsize is 992 - this is slightly, but
   significantly, faster than 1024 or very large buffer sizes. I'm not
   sure why this is - maybe some strange interaction between the
   filesystem blocksize and the page size? */

#define INBUFSIZE 992  
#define MIDBUFSIZE 1024  /* for key change */
#define OUTBUFSIZE 1056

/* ---------------------------------------------------------------------- */
/* ccrypt error messages. These correspond to the error codes returned
   by the ccrypt functions. Note: the error code -1 corresponds to a
   system error, with errno set, and the error code -2 corresponds to
   a ccrypt error, with ccrypt_errno set. */

const char *ccrypt_error(int st) {
  if (st == -1) {
    return strerror(errno);
  } else if (st == -2) {
    return ccrypt_errstr[ccrypt_errno];
  } else {
    return "unknown error";
  }
}

/* ---------------------------------------------------------------------- */
/* keychange = compose decryption and encryption */

struct keychange_state_s {
  ccrypt_stream_t b1;
  ccrypt_stream_t b2;
  int iv;                /* count-down for IV bytes */
  char buf[MIDBUFSIZE];
};
typedef struct keychange_state_s keychange_state_t;

static int keychange_init(ccrypt_stream_t *b, char *key1, char *key2) {
  keychange_state_t *st;
  int r;

  st = malloc(sizeof(keychange_state_t));
  if (st == NULL) {
    return -1;
  }
  b->state = (void *)st;

  r = ccdecrypt_init(&st->b1, key1, 0);
  if (r) {
    return r;
  }
  r = ccencrypt_init(&st->b2, key2);
  if (r) {
    return r;
  }
  st->b2.next_in = &st->buf[0];
  st->b2.avail_in = 0;
  st->iv = 32;  /* count down IV bytes */

  return 0;
}

static int keychange(ccrypt_stream_t *b) {
  keychange_state_t *st = (keychange_state_t *)b->state;
  int r;

  /* note: we do not write anything until we have seen 32 bytes of
     input. This way, we don't write the output IV until the input IV
     has been verified. */

  while (1) { 
    /* clear mid-buffer */
    if (b->avail_out && !st->iv) {
      st->b2.next_out = b->next_out;
      st->b2.avail_out = b->avail_out;
      r = ccencrypt(&st->b2);
      if (r) {
	return r;
      }
      b->next_out = st->b2.next_out;
      b->avail_out = st->b2.avail_out;
    }
    
    /* if mid-buffer not empty, or no input available, stop */
    if (st->b2.avail_in != 0 || b->avail_in == 0) {
      break;
    }

    /* fill mid-buffer */
    st->b1.next_out = &st->buf[0];
    st->b1.avail_out = MIDBUFSIZE;
    st->b1.next_in = b->next_in;
    st->b1.avail_in = b->avail_in;
    r = ccdecrypt(&st->b1);
    if (r) {
      return r;
    }
    if (st->iv) {
      st->iv -= b->avail_in - st->b1.avail_in;
      if (st->iv <= 0) {
	st->iv = 0;
      }
    }
    b->next_in = st->b1.next_in;
    b->avail_in = st->b1.avail_in;
    st->b2.next_in = &st->buf[0];
    st->b2.avail_in = st->b1.next_out - st->b2.next_in;
  }
  return 0;
}

static int keychange_end(ccrypt_stream_t *b) {
  keychange_state_t *st = (keychange_state_t *)b->state;
  int r, cerr, err;

  r = ccdecrypt_end(&st->b1);
  if (r) {
    cerr = ccrypt_errno;
    err = errno;
    ccencrypt_end(&st->b2);
    free(b->state);
    b->state = NULL;
    ccrypt_errno = cerr;
    errno = err;
    return r;
  }
  r = ccencrypt_end(&st->b2);
  if (r) {
    cerr = ccrypt_errno;
    err = errno;
    free(b->state);
    b->state = NULL;
    ccrypt_errno = cerr;
    errno = err;
    return r;
  }
  free(b->state);
  b->state = NULL;
  return 0;
}

/* ---------------------------------------------------------------------- */
/* encryption/decryption of streams */

typedef int initfun(ccrypt_stream_t *b, char *key);
typedef int workfun(ccrypt_stream_t *b);
typedef int endfun(ccrypt_stream_t *b);

/* apply ccrypt_stream to pipe stuff from fin to fout. Assume the
   ccrypt_stream has already been initialized. */
static int streamhandler(ccrypt_stream_t *b, workfun *work, endfun *end, 
			 FILE *fin, FILE *fout) {
  /* maybe should align buffers on page boundary */
  char inbuf[INBUFSIZE], outbuf[OUTBUFSIZE]; 
  int eof = 0;
  int r;
  int cerr, err;

  b->avail_in = 0;

  while (1) {
    /* fill input buffer */
    if (b->avail_in == 0 && !eof) {
      r = fread(inbuf, 1, INBUFSIZE, fin);
      b->next_in = &inbuf[0];
      b->avail_in = r;
      if (r<INBUFSIZE) {
	eof = 1;
      }
    }
    /* prepare output buffer */
    b->next_out = &outbuf[0];
    b->avail_out = OUTBUFSIZE;

    /* do some work */
    r = work(b);
    if (r) {
      cerr = ccrypt_errno;
      err = errno;
      end(b);
      ccrypt_errno = cerr;
      errno = err;
      return r;
    }
    /* process output buffer */
    if (b->avail_out < OUTBUFSIZE) {
      fwrite(outbuf, 1, OUTBUFSIZE-b->avail_out, fout);
    }
    if (eof && b->avail_out != 0) {
      break;
    }
  }
  r = end(b);
  if (r) {
    return r;
  }
  return 0;
}  

int ccencrypt_streams(FILE *fin, FILE *fout, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = ccencrypt_init(b, key);
  if (r) {
    return r;
  }

  return streamhandler(b, ccencrypt, ccencrypt_end, fin, fout);
}

int ccdecrypt_streams(FILE *fin, FILE *fout, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;
  int flags = 0;

  if (cmd.mismatch) {
    flags |= CCRYPT_MISMATCH;
  }

  r = ccdecrypt_init(b, key, flags);
  if (r) {
    return r;
  }

  return streamhandler(b, ccdecrypt, ccdecrypt_end, fin, fout);
}

int cckeychange_streams(FILE *fin, FILE *fout, char *key1, char *key2) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = keychange_init(b, key1, key2);
  if (r) {
    return r;
  }

  return streamhandler(b, keychange, keychange_end, fin, fout);
}

int unixcrypt_streams(FILE *fin, FILE *fout, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = unixcrypt_init(b, key);
  if (r) {
    return r;
  }

  return streamhandler(b, unixcrypt, unixcrypt_end, fin, fout);
}

/* ---------------------------------------------------------------------- */
/* destructive encryption/decryption of files */

/* A large value of FILEINBUFSIZE keeps the cost of "lseek" down. It
   is okay for FILEINBUFSIZE to be much larger than MIDBUFSIZE.
   FILEOUTBUFSIZE must be large enough to hold the encryption of
   FILEINBUFSIZE in one piece, or otherwise there will be a buffer
   overflow error. */

#define FILEINBUFSIZE 10240
#define FILEOUTBUFSIZE (FILEINBUFSIZE+32)

/* apply ccrypt_stream to destructively update (and resize) the given
   fd, which must be opened in read/write mode and seekable.
   Encryption will begin at the current file position (normally 0),
   and extend until the end of the file. Note: this only works if the
   stream encoder b/work/end expands its input by at most
   FILEINBUFSIZE bytes; otherwise there will be a buffer overflow
   error. */

static int filehandler(ccrypt_stream_t *b, workfun *work, endfun *end,
		       int fd) {
  /* rp = reader's position, wp = writer's position, fp = file position */
  int p;      /* rp-wp */
  char inbuf[FILEINBUFSIZE];
  char outbuf[FILEINBUFSIZE+32];
  int inbufsize, outbufsize;
  off_t offs;
  int r;
  int i;
  int eof=0;
  int err, errc;

  p = 0;
  outbufsize = 0;

  while (1) {
    /* file is at position wp */
    if (p != 0) {
      r = lseek(fd, p, SEEK_CUR);
      if (r == -1) {
	goto error;
      }
    }
    /* file is at position rp */

    /* read block */
    i = 0;
    while (i<FILEINBUFSIZE && !eof) {
      r = read(fd, inbuf+i, FILEINBUFSIZE-i);
      if (r == -1) {
	goto error;
      } else if (r==0) {
	eof = 1;
      }
      i += r;
    }
    p += i;
    inbufsize = i;

    /* file is at position rp */
    if (p != 0) {
      r = lseek(fd, -p, SEEK_CUR);
      if (r == -1) {
	goto error;
      }
    }
    /* file is at position wp */

    /* write previous block */
    if (outbufsize > p && !eof) {
      ccrypt_errno = CCRYPT_EBUFFER; /* buffer overflow; should never happen */
      r = -2;
      goto error;
    }
    if (outbufsize != 0) {
      i = 0;
      while (i<outbufsize) {
	r = write(fd, outbuf+i, outbufsize-i);
	if (r == -1) {
	  goto error;
	}
	i += r;
      }
      p -= outbufsize;
      outbufsize = 0;
    }
    
    /* encrypt block */
    b->next_in = inbuf;
    b->avail_in = inbufsize;
    b->next_out = outbuf;
    b->avail_out = FILEINBUFSIZE+32;

    r = work(b);
    if (r) {
      goto error;
    }      
    
    if (b->avail_in != 0) {
      ccrypt_errno = CCRYPT_EBUFFER; /* buffer overflow; should never happen */
      r = -2;
      goto error;
    }
    inbufsize = 0;
    outbufsize = FILEINBUFSIZE+32-b->avail_out;

    if (eof && outbufsize == 0) { /* done */
      break;
    }
  }
  /* file is at position wp */

  /* close the stream (we need to do this before truncating, because
     there might be an error!) */
  r = end(b);
  if (r) {
    return r;
  }

  /* truncate the file to where it's been written */
  r = offs = lseek(fd, 0, SEEK_CUR);
  if (r == -1) {
    return -1;
  }
  r = ftruncate(fd, offs);
  if (r == -1) {
    return -1;
  }
  
  return 0;

 error:
  err = errno;
  errc = ccrypt_errno;
  end(b);
  errno = err;
  ccrypt_errno = errc;
  return r;
}

int ccencrypt_file(int fd, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = ccencrypt_init(b, key);
  if (r) {
    return r;
  }

  return filehandler(b, ccencrypt, ccencrypt_end, fd);
}

int ccdecrypt_file(int fd, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = ccdecrypt_init(b, key, 0);
  if (r) {
    return r;
  }

  return filehandler(b, ccdecrypt, ccdecrypt_end, fd);
}

int cckeychange_file(int fd, char *key1, char *key2) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = keychange_init(b, key1, key2);
  if (r) {
    return r;
  }

  return filehandler(b, keychange, keychange_end, fd);
}

int unixcrypt_file(int fd, char *key) {
  ccrypt_stream_t ccs;
  ccrypt_stream_t *b = &ccs;
  int r;

  r = unixcrypt_init(b, key);
  if (r) {
    return r;
  }

  return filehandler(b, unixcrypt, unixcrypt_end, fd);
}