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1.17.14
: grub-core/lib/libgcrypt-grub/cipher/elgamal.c
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- Committer: Bazaar Package Importer
- Author(s): Colin Watson
- Date: 2011-01-17 13:43:06 UTC
- mto: (17.6.26 experimental)
- mto: This revision was merged to the branch mainline in revision 102.
- Revision ID: james.westby@ubuntu.com-20110117134306-fy7qewn4s3qdx2pl
Tags: upstream-1.99~rc1
Import upstream version 1.99~rc1
- files added:
- Makefile.in
- autom4te.cache
- grub-core/lib/libgcrypt-grub
- grub-core/lib/libgcrypt-grub/cipher
- files removed:
- po/LINGUAS
- files modified:
- .bzrignore
added
removed
grub-core/lib/libgcrypt-grub/cipher/elgamal.c
1
/* This file was automatically imported with
2
import_gcry.py. Please don't modify it */
3
/* Elgamal.c - Elgamal Public Key encryption
4
* Copyright (C) 1998, 2000, 2001, 2002, 2003,
5
* 2008 Free Software Foundation, Inc.
6
*
7
* This file is part of Libgcrypt.
8
*
9
* Libgcrypt is free software; you can redistribute it and/or modify
10
* it under the terms of the GNU Lesser General Public License as
11
* published by the Free Software Foundation; either version 2.1 of
12
* the License, or (at your option) any later version.
13
*
14
* Libgcrypt is distributed in the hope that it will be useful,
15
* but WITHOUT ANY WARRANTY; without even the implied warranty of
16
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17
* GNU Lesser General Public License for more details.
18
*
19
* You should have received a copy of the GNU Lesser General Public
20
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
21
*
22
* For a description of the algorithm, see:
23
* Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
24
* ISBN 0-471-11709-9. Pages 476 ff.
25
*/
26
27
#include "g10lib.h"
28
#include "mpi.h"
29
#include "cipher.h"
30
31
typedef struct
32
{
33
gcry_mpi_t p; /* prime */
34
gcry_mpi_t g; /* group generator */
35
gcry_mpi_t y; /* g^x mod p */
36
} ELG_public_key;
37
38
39
typedef struct
40
{
41
gcry_mpi_t p; /* prime */
42
gcry_mpi_t g; /* group generator */
43
gcry_mpi_t y; /* g^x mod p */
44
gcry_mpi_t x; /* secret exponent */
45
} ELG_secret_key;
46
47
48
static int test_keys (ELG_secret_key *sk, unsigned int nbits, int nodie);
49
static gcry_mpi_t gen_k (gcry_mpi_t p, int small_k);
50
static void generate (ELG_secret_key *sk, unsigned nbits, gcry_mpi_t **factors);
51
static int check_secret_key (ELG_secret_key *sk);
52
static void do_encrypt (gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input,
53
ELG_public_key *pkey);
54
static void decrypt (gcry_mpi_t output, gcry_mpi_t a, gcry_mpi_t b,
55
ELG_secret_key *skey);
56
static void sign (gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input,
57
ELG_secret_key *skey);
58
static int verify (gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input,
59
ELG_public_key *pkey);
60
61
62
static void (*progress_cb) (void *, const char *, int, int, int);
63
static void *progress_cb_data;
64
65
void
66
_gcry_register_pk_elg_progress (void (*cb) (void *, const char *,
67
int, int, int),
68
void *cb_data)
69
{
70
progress_cb = cb;
71
progress_cb_data = cb_data;
72
}
73
74
75
static void
76
progress (int c)
77
{
78
if (progress_cb)
79
progress_cb (progress_cb_data, "pk_elg", c, 0, 0);
80
}
81
82
83
/****************
84
* Michael Wiener's table on subgroup sizes to match field sizes.
85
* (floating around somewhere, probably based on the paper from
86
* Eurocrypt 96, page 332)
87
*/
88
static unsigned int
89
wiener_map( unsigned int n )
90
{
91
static struct { unsigned int p_n, q_n; } t[] =
92
{ /* p q attack cost */
93
{ 512, 119 }, /* 9 x 10^17 */
94
{ 768, 145 }, /* 6 x 10^21 */
95
{ 1024, 165 }, /* 7 x 10^24 */
96
{ 1280, 183 }, /* 3 x 10^27 */
97
{ 1536, 198 }, /* 7 x 10^29 */
98
{ 1792, 212 }, /* 9 x 10^31 */
99
{ 2048, 225 }, /* 8 x 10^33 */
100
{ 2304, 237 }, /* 5 x 10^35 */
101
{ 2560, 249 }, /* 3 x 10^37 */
102
{ 2816, 259 }, /* 1 x 10^39 */
103
{ 3072, 269 }, /* 3 x 10^40 */
104
{ 3328, 279 }, /* 8 x 10^41 */
105
{ 3584, 288 }, /* 2 x 10^43 */
106
{ 3840, 296 }, /* 4 x 10^44 */
107
{ 4096, 305 }, /* 7 x 10^45 */
108
{ 4352, 313 }, /* 1 x 10^47 */
109
{ 4608, 320 }, /* 2 x 10^48 */
110
{ 4864, 328 }, /* 2 x 10^49 */
111
{ 5120, 335 }, /* 3 x 10^50 */
112
{ 0, 0 }
113
};
114
int i;
115
116
for(i=0; t[i].p_n; i++ )
117
{
118
if( n <= t[i].p_n )
119
return t[i].q_n;
120
}
121
/* Not in table - use an arbitrary high number. */
122
return n / 8 + 200;
123
}
124
125
static int
126
test_keys ( ELG_secret_key *sk, unsigned int nbits, int nodie )
127
{
128
ELG_public_key pk;
129
gcry_mpi_t test = gcry_mpi_new ( 0 );
130
gcry_mpi_t out1_a = gcry_mpi_new ( nbits );
131
gcry_mpi_t out1_b = gcry_mpi_new ( nbits );
132
gcry_mpi_t out2 = gcry_mpi_new ( nbits );
133
int failed = 0;
134
135
pk.p = sk->p;
136
pk.g = sk->g;
137
pk.y = sk->y;
138
139
gcry_mpi_randomize ( test, nbits, GCRY_WEAK_RANDOM );
140
141
do_encrypt ( out1_a, out1_b, test, &pk );
142
decrypt ( out2, out1_a, out1_b, sk );
143
if ( mpi_cmp( test, out2 ) )
144
failed |= 1;
145
146
sign ( out1_a, out1_b, test, sk );
147
if ( !verify( out1_a, out1_b, test, &pk ) )
148
failed |= 2;
149
150
gcry_mpi_release ( test );
151
gcry_mpi_release ( out1_a );
152
gcry_mpi_release ( out1_b );
153
gcry_mpi_release ( out2 );
154
155
if (failed && !nodie)
156
log_fatal ("Elgamal test key for %s %s failed\n",
157
(failed & 1)? "encrypt+decrypt":"",
158
(failed & 2)? "sign+verify":"");
159
if (failed && DBG_CIPHER)
160
log_debug ("Elgamal test key for %s %s failed\n",
161
(failed & 1)? "encrypt+decrypt":"",
162
(failed & 2)? "sign+verify":"");
163
164
return failed;
165
}
166
167
168
/****************
169
* Generate a random secret exponent k from prime p, so that k is
170
* relatively prime to p-1. With SMALL_K set, k will be selected for
171
* better encryption performance - this must never be used signing!
172
*/
173
static gcry_mpi_t
174
gen_k( gcry_mpi_t p, int small_k )
175
{
176
gcry_mpi_t k = mpi_alloc_secure( 0 );
177
gcry_mpi_t temp = mpi_alloc( mpi_get_nlimbs(p) );
178
gcry_mpi_t p_1 = mpi_copy(p);
179
unsigned int orig_nbits = mpi_get_nbits(p);
180
unsigned int nbits, nbytes;
181
char *rndbuf = NULL;
182
183
if (small_k)
184
{
185
/* Using a k much lesser than p is sufficient for encryption and
186
* it greatly improves the encryption performance. We use
187
* Wiener's table and add a large safety margin. */
188
nbits = wiener_map( orig_nbits ) * 3 / 2;
189
if( nbits >= orig_nbits )
190
BUG();
191
}
192
else
193
nbits = orig_nbits;
194
195
196
nbytes = (nbits+7)/8;
197
if( DBG_CIPHER )
198
log_debug("choosing a random k ");
199
mpi_sub_ui( p_1, p, 1);
200
for(;;)
201
{
202
if( !rndbuf || nbits < 32 )
203
{
204
gcry_free(rndbuf);
205
rndbuf = gcry_random_bytes_secure( nbytes, GCRY_STRONG_RANDOM );
206
}
207
else
208
{
209
/* Change only some of the higher bits. We could improve
210
this by directly requesting more memory at the first call
211
to get_random_bytes() and use this the here maybe it is
212
easier to do this directly in random.c Anyway, it is
213
highly inlikely that we will ever reach this code. */
214
char *pp = gcry_random_bytes_secure( 4, GCRY_STRONG_RANDOM );
215
memcpy( rndbuf, pp, 4 );
216
gcry_free(pp);
217
}
218
_gcry_mpi_set_buffer( k, rndbuf, nbytes, 0 );
219
220
for(;;)
221
{
222
if( !(mpi_cmp( k, p_1 ) < 0) ) /* check: k < (p-1) */
223
{
224
if( DBG_CIPHER )
225
progress('+');
226
break; /* no */
227
}
228
if( !(mpi_cmp_ui( k, 0 ) > 0) ) /* check: k > 0 */
229
{
230
if( DBG_CIPHER )
231
progress('-');
232
break; /* no */
233
}
234
if (gcry_mpi_gcd( temp, k, p_1 ))
235
goto found; /* okay, k is relative prime to (p-1) */
236
mpi_add_ui( k, k, 1 );
237
if( DBG_CIPHER )
238
progress('.');
239
}
240
}
241
found:
242
gcry_free(rndbuf);
243
if( DBG_CIPHER )
244
progress('\n');
245
mpi_free(p_1);
246
mpi_free(temp);
247
248
return k;
249
}
250
251
/****************
252
* Generate a key pair with a key of size NBITS
253
* Returns: 2 structures filled with all needed values
254
* and an array with n-1 factors of (p-1)
255
*/
256
static void
257
generate ( ELG_secret_key *sk, unsigned int nbits, gcry_mpi_t **ret_factors )
258
{
259
gcry_mpi_t p; /* the prime */
260
gcry_mpi_t p_min1;
261
gcry_mpi_t g;
262
gcry_mpi_t x; /* the secret exponent */
263
gcry_mpi_t y;
264
unsigned int qbits;
265
unsigned int xbits;
266
byte *rndbuf;
267
268
p_min1 = gcry_mpi_new ( nbits );
269
qbits = wiener_map( nbits );
270
if( qbits & 1 ) /* better have a even one */
271
qbits++;
272
g = mpi_alloc(1);
273
p = _gcry_generate_elg_prime( 0, nbits, qbits, g, ret_factors );
274
mpi_sub_ui(p_min1, p, 1);
275
276
277
/* Select a random number which has these properties:
278
* 0 < x < p-1
279
* This must be a very good random number because this is the
280
* secret part. The prime is public and may be shared anyway,
281
* so a random generator level of 1 is used for the prime.
282
*
283
* I don't see a reason to have a x of about the same size
284
* as the p. It should be sufficient to have one about the size
285
* of q or the later used k plus a large safety margin. Decryption
286
* will be much faster with such an x.
287
*/
288
xbits = qbits * 3 / 2;
289
if( xbits >= nbits )
290
BUG();
291
x = gcry_mpi_snew ( xbits );
292
if( DBG_CIPHER )
293
log_debug("choosing a random x of size %u", xbits );
294
rndbuf = NULL;
295
do
296
{
297
if( DBG_CIPHER )
298
progress('.');
299
if( rndbuf )
300
{ /* Change only some of the higher bits */
301
if( xbits < 16 ) /* should never happen ... */
302
{
303
gcry_free(rndbuf);
304
rndbuf = gcry_random_bytes_secure( (xbits+7)/8,
305
GCRY_VERY_STRONG_RANDOM );
306
}
307
else
308
{
309
char *r = gcry_random_bytes_secure( 2,
310
GCRY_VERY_STRONG_RANDOM );
311
memcpy(rndbuf, r, 2 );
312
gcry_free(r);
313
}
314
}
315
else
316
{
317
rndbuf = gcry_random_bytes_secure( (xbits+7)/8,
318
GCRY_VERY_STRONG_RANDOM );
319
}
320
_gcry_mpi_set_buffer( x, rndbuf, (xbits+7)/8, 0 );
321
mpi_clear_highbit( x, xbits+1 );
322
}
323
while( !( mpi_cmp_ui( x, 0 )>0 && mpi_cmp( x, p_min1 )<0 ) );
324
gcry_free(rndbuf);
325
326
y = gcry_mpi_new (nbits);
327
gcry_mpi_powm( y, g, x, p );
328
329
if( DBG_CIPHER )
330
{
331
progress('\n');
332
log_mpidump("elg p= ", p );
333
log_mpidump("elg g= ", g );
334
log_mpidump("elg y= ", y );
335
log_mpidump("elg x= ", x );
336
}
337
338
/* Copy the stuff to the key structures */
339
sk->p = p;
340
sk->g = g;
341
sk->y = y;
342
sk->x = x;
343
344
gcry_mpi_release ( p_min1 );
345
346
/* Now we can test our keys (this should never fail!) */
347
test_keys ( sk, nbits - 64, 0 );
348
}
349
350
351
/* Generate a key pair with a key of size NBITS not using a random
352
value for the secret key but the one given as X. This is useful to
353
implement a passphrase based decryption for a public key based
354
encryption. It has appliactions in backup systems.
355
356
Returns: A structure filled with all needed values and an array
357
with n-1 factors of (p-1). */
358
static gcry_err_code_t
359
generate_using_x (ELG_secret_key *sk, unsigned int nbits, gcry_mpi_t x,
360
gcry_mpi_t **ret_factors )
361
{
362
gcry_mpi_t p; /* The prime. */
363
gcry_mpi_t p_min1; /* The prime minus 1. */
364
gcry_mpi_t g; /* The generator. */
365
gcry_mpi_t y; /* g^x mod p. */
366
unsigned int qbits;
367
unsigned int xbits;
368
369
sk->p = NULL;
370
sk->g = NULL;
371
sk->y = NULL;
372
sk->x = NULL;
373
374
/* Do a quick check to see whether X is suitable. */
375
xbits = mpi_get_nbits (x);
376
if ( xbits < 64 || xbits >= nbits )
377
return GPG_ERR_INV_VALUE;
378
379
p_min1 = gcry_mpi_new ( nbits );
380
qbits = wiener_map ( nbits );
381
if ( (qbits & 1) ) /* Better have an even one. */
382
qbits++;
383
g = mpi_alloc (1);
384
p = _gcry_generate_elg_prime ( 0, nbits, qbits, g, ret_factors );
385
mpi_sub_ui (p_min1, p, 1);
386
387
if (DBG_CIPHER)
388
log_debug ("using a supplied x of size %u", xbits );
389
if ( !(mpi_cmp_ui ( x, 0 ) > 0 && mpi_cmp ( x, p_min1 ) <0 ) )
390
{
391
gcry_mpi_release ( p_min1 );
392
gcry_mpi_release ( p );
393
gcry_mpi_release ( g );
394
return GPG_ERR_INV_VALUE;
395
}
396
397
y = gcry_mpi_new (nbits);
398
gcry_mpi_powm ( y, g, x, p );
399
400
if ( DBG_CIPHER )
401
{
402
progress ('\n');
403
log_mpidump ("elg p= ", p );
404
log_mpidump ("elg g= ", g );
405
log_mpidump ("elg y= ", y );
406
log_mpidump ("elg x= ", x );
407
}
408
409
/* Copy the stuff to the key structures */
410
sk->p = p;
411
sk->g = g;
412
sk->y = y;
413
sk->x = gcry_mpi_copy (x);
414
415
gcry_mpi_release ( p_min1 );
416
417
/* Now we can test our keys. */
418
if ( test_keys ( sk, nbits - 64, 1 ) )
419
{
420
gcry_mpi_release ( sk->p ); sk->p = NULL;
421
gcry_mpi_release ( sk->g ); sk->g = NULL;
422
gcry_mpi_release ( sk->y ); sk->y = NULL;
423
gcry_mpi_release ( sk->x ); sk->x = NULL;
424
return GPG_ERR_BAD_SECKEY;
425
}
426
427
return 0;
428
}
429
430
431
/****************
432
* Test whether the secret key is valid.
433
* Returns: if this is a valid key.
434
*/
435
static int
436
check_secret_key( ELG_secret_key *sk )
437
{
438
int rc;
439
gcry_mpi_t y = mpi_alloc( mpi_get_nlimbs(sk->y) );
440
441
gcry_mpi_powm( y, sk->g, sk->x, sk->p );
442
rc = !mpi_cmp( y, sk->y );
443
mpi_free( y );
444
return rc;
445
}
446
447
448
static void
449
do_encrypt(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_public_key *pkey )
450
{
451
gcry_mpi_t k;
452
453
/* Note: maybe we should change the interface, so that it
454
* is possible to check that input is < p and return an
455
* error code.
456
*/
457
458
k = gen_k( pkey->p, 1 );
459
gcry_mpi_powm( a, pkey->g, k, pkey->p );
460
/* b = (y^k * input) mod p
461
* = ((y^k mod p) * (input mod p)) mod p
462
* and because input is < p
463
* = ((y^k mod p) * input) mod p
464
*/
465
gcry_mpi_powm( b, pkey->y, k, pkey->p );
466
gcry_mpi_mulm( b, b, input, pkey->p );
467
#if 0
468
if( DBG_CIPHER )
469
{
470
log_mpidump("elg encrypted y= ", pkey->y);
471
log_mpidump("elg encrypted p= ", pkey->p);
472
log_mpidump("elg encrypted k= ", k);
473
log_mpidump("elg encrypted M= ", input);
474
log_mpidump("elg encrypted a= ", a);
475
log_mpidump("elg encrypted b= ", b);
476
}
477
#endif
478
mpi_free(k);
479
}
480
481
482
483
484
static void
485
decrypt(gcry_mpi_t output, gcry_mpi_t a, gcry_mpi_t b, ELG_secret_key *skey )
486
{
487
gcry_mpi_t t1 = mpi_alloc_secure( mpi_get_nlimbs( skey->p ) );
488
489
/* output = b/(a^x) mod p */
490
gcry_mpi_powm( t1, a, skey->x, skey->p );
491
mpi_invm( t1, t1, skey->p );
492
mpi_mulm( output, b, t1, skey->p );
493
#if 0
494
if( DBG_CIPHER )
495
{
496
log_mpidump("elg decrypted x= ", skey->x);
497
log_mpidump("elg decrypted p= ", skey->p);
498
log_mpidump("elg decrypted a= ", a);
499
log_mpidump("elg decrypted b= ", b);
500
log_mpidump("elg decrypted M= ", output);
501
}
502
#endif
503
mpi_free(t1);
504
}
505
506
507
/****************
508
* Make an Elgamal signature out of INPUT
509
*/
510
511
static void
512
sign(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_secret_key *skey )
513
{
514
gcry_mpi_t k;
515
gcry_mpi_t t = mpi_alloc( mpi_get_nlimbs(a) );
516
gcry_mpi_t inv = mpi_alloc( mpi_get_nlimbs(a) );
517
gcry_mpi_t p_1 = mpi_copy(skey->p);
518
519
/*
520
* b = (t * inv) mod (p-1)
521
* b = (t * inv(k,(p-1),(p-1)) mod (p-1)
522
* b = (((M-x*a) mod (p-1)) * inv(k,(p-1),(p-1))) mod (p-1)
523
*
524
*/
525
mpi_sub_ui(p_1, p_1, 1);
526
k = gen_k( skey->p, 0 /* no small K ! */ );
527
gcry_mpi_powm( a, skey->g, k, skey->p );
528
mpi_mul(t, skey->x, a );
529
mpi_subm(t, input, t, p_1 );
530
mpi_invm(inv, k, p_1 );
531
mpi_mulm(b, t, inv, p_1 );
532
533
#if 0
534
if( DBG_CIPHER )
535
{
536
log_mpidump("elg sign p= ", skey->p);
537
log_mpidump("elg sign g= ", skey->g);
538
log_mpidump("elg sign y= ", skey->y);
539
log_mpidump("elg sign x= ", skey->x);
540
log_mpidump("elg sign k= ", k);
541
log_mpidump("elg sign M= ", input);
542
log_mpidump("elg sign a= ", a);
543
log_mpidump("elg sign b= ", b);
544
}
545
#endif
546
mpi_free(k);
547
mpi_free(t);
548
mpi_free(inv);
549
mpi_free(p_1);
550
}
551
552
553
/****************
554
* Returns true if the signature composed of A and B is valid.
555
*/
556
static int
557
verify(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_public_key *pkey )
558
{
559
int rc;
560
gcry_mpi_t t1;
561
gcry_mpi_t t2;
562
gcry_mpi_t base[4];
563
gcry_mpi_t ex[4];
564
565
if( !(mpi_cmp_ui( a, 0 ) > 0 && mpi_cmp( a, pkey->p ) < 0) )
566
return 0; /* assertion 0 < a < p failed */
567
568
t1 = mpi_alloc( mpi_get_nlimbs(a) );
569
t2 = mpi_alloc( mpi_get_nlimbs(a) );
570
571
#if 0
572
/* t1 = (y^a mod p) * (a^b mod p) mod p */
573
gcry_mpi_powm( t1, pkey->y, a, pkey->p );
574
gcry_mpi_powm( t2, a, b, pkey->p );
575
mpi_mulm( t1, t1, t2, pkey->p );
576
577
/* t2 = g ^ input mod p */
578
gcry_mpi_powm( t2, pkey->g, input, pkey->p );
579
580
rc = !mpi_cmp( t1, t2 );
581
#elif 0
582
/* t1 = (y^a mod p) * (a^b mod p) mod p */
583
base[0] = pkey->y; ex[0] = a;
584
base[1] = a; ex[1] = b;
585
base[2] = NULL; ex[2] = NULL;
586
mpi_mulpowm( t1, base, ex, pkey->p );
587
588
/* t2 = g ^ input mod p */
589
gcry_mpi_powm( t2, pkey->g, input, pkey->p );
590
591
rc = !mpi_cmp( t1, t2 );
592
#else
593
/* t1 = g ^ - input * y ^ a * a ^ b mod p */
594
mpi_invm(t2, pkey->g, pkey->p );
595
base[0] = t2 ; ex[0] = input;
596
base[1] = pkey->y; ex[1] = a;
597
base[2] = a; ex[2] = b;
598
base[3] = NULL; ex[3] = NULL;
599
mpi_mulpowm( t1, base, ex, pkey->p );
600
rc = !mpi_cmp_ui( t1, 1 );
601
602
#endif
603
604
mpi_free(t1);
605
mpi_free(t2);
606
return rc;
607
}
608
609
/*********************************************
610
************** interface ******************
611
*********************************************/
612
613
static gpg_err_code_t
614
elg_generate_ext (int algo, unsigned int nbits, unsigned long evalue,
615
const gcry_sexp_t genparms,
616
gcry_mpi_t *skey, gcry_mpi_t **retfactors,
617
gcry_sexp_t *r_extrainfo)
618
{
619
gpg_err_code_t ec;
620
ELG_secret_key sk;
621
gcry_mpi_t xvalue = NULL;
622
gcry_sexp_t l1;
623
624
(void)algo;
625
(void)evalue;
626
(void)r_extrainfo;
627
628
if (genparms)
629
{
630
/* Parse the optional xvalue element. */
631
l1 = gcry_sexp_find_token (genparms, "xvalue", 0);
632
if (l1)
633
{
634
xvalue = gcry_sexp_nth_mpi (l1, 1, 0);
635
gcry_sexp_release (l1);
636
if (!xvalue)
637
return GPG_ERR_BAD_MPI;
638
}
639
}
640
641
if (xvalue)
642
ec = generate_using_x (&sk, nbits, xvalue, retfactors);
643
else
644
{
645
generate (&sk, nbits, retfactors);
646
ec = 0;
647
}
648
649
skey[0] = sk.p;
650
skey[1] = sk.g;
651
skey[2] = sk.y;
652
skey[3] = sk.x;
653
654
return ec;
655
}
656
657
658
static gcry_err_code_t
659
elg_generate (int algo, unsigned int nbits, unsigned long evalue,
660
gcry_mpi_t *skey, gcry_mpi_t **retfactors)
661
{
662
ELG_secret_key sk;
663
664
(void)algo;
665
(void)evalue;
666
667
generate (&sk, nbits, retfactors);
668
skey[0] = sk.p;
669
skey[1] = sk.g;
670
skey[2] = sk.y;
671
skey[3] = sk.x;
672
673
return GPG_ERR_NO_ERROR;
674
}
675
676
677
static gcry_err_code_t
678
elg_check_secret_key (int algo, gcry_mpi_t *skey)
679
{
680
gcry_err_code_t err = GPG_ERR_NO_ERROR;
681
ELG_secret_key sk;
682
683
(void)algo;
684
685
if ((! skey[0]) || (! skey[1]) || (! skey[2]) || (! skey[3]))
686
err = GPG_ERR_BAD_MPI;
687
else
688
{
689
sk.p = skey[0];
690
sk.g = skey[1];
691
sk.y = skey[2];
692
sk.x = skey[3];
693
694
if (! check_secret_key (&sk))
695
err = GPG_ERR_BAD_SECKEY;
696
}
697
698
return err;
699
}
700
701
702
static gcry_err_code_t
703
elg_encrypt (int algo, gcry_mpi_t *resarr,
704
gcry_mpi_t data, gcry_mpi_t *pkey, int flags)
705
{
706
gcry_err_code_t err = GPG_ERR_NO_ERROR;
707
ELG_public_key pk;
708
709
(void)algo;
710
(void)flags;
711
712
if ((! data) || (! pkey[0]) || (! pkey[1]) || (! pkey[2]))
713
err = GPG_ERR_BAD_MPI;
714
else
715
{
716
pk.p = pkey[0];
717
pk.g = pkey[1];
718
pk.y = pkey[2];
719
resarr[0] = mpi_alloc (mpi_get_nlimbs (pk.p));
720
resarr[1] = mpi_alloc (mpi_get_nlimbs (pk.p));
721
do_encrypt (resarr[0], resarr[1], data, &pk);
722
}
723
return err;
724
}
725
726
727
static gcry_err_code_t
728
elg_decrypt (int algo, gcry_mpi_t *result,
729
gcry_mpi_t *data, gcry_mpi_t *skey, int flags)
730
{
731
gcry_err_code_t err = GPG_ERR_NO_ERROR;
732
ELG_secret_key sk;
733
734
(void)algo;
735
(void)flags;
736
737
if ((! data[0]) || (! data[1])
738
|| (! skey[0]) || (! skey[1]) || (! skey[2]) || (! skey[3]))
739
err = GPG_ERR_BAD_MPI;
740
else
741
{
742
sk.p = skey[0];
743
sk.g = skey[1];
744
sk.y = skey[2];
745
sk.x = skey[3];
746
*result = mpi_alloc_secure (mpi_get_nlimbs (sk.p));
747
decrypt (*result, data[0], data[1], &sk);
748
}
749
return err;
750
}
751
752
753
static gcry_err_code_t
754
elg_sign (int algo, gcry_mpi_t *resarr, gcry_mpi_t data, gcry_mpi_t *skey)
755
{
756
gcry_err_code_t err = GPG_ERR_NO_ERROR;
757
ELG_secret_key sk;
758
759
(void)algo;
760
761
if ((! data)
762
|| (! skey[0]) || (! skey[1]) || (! skey[2]) || (! skey[3]))
763
err = GPG_ERR_BAD_MPI;
764
else
765
{
766
sk.p = skey[0];
767
sk.g = skey[1];
768
sk.y = skey[2];
769
sk.x = skey[3];
770
resarr[0] = mpi_alloc (mpi_get_nlimbs (sk.p));
771
resarr[1] = mpi_alloc (mpi_get_nlimbs (sk.p));
772
sign (resarr[0], resarr[1], data, &sk);
773
}
774
775
return err;
776
}
777
778
779
static gcry_err_code_t
780
elg_verify (int algo, gcry_mpi_t hash, gcry_mpi_t *data, gcry_mpi_t *pkey,
781
int (*cmp) (void *, gcry_mpi_t), void *opaquev)
782
{
783
gcry_err_code_t err = GPG_ERR_NO_ERROR;
784
ELG_public_key pk;
785
786
(void)algo;
787
(void)cmp;
788
(void)opaquev;
789
790
if ((! data[0]) || (! data[1]) || (! hash)
791
|| (! pkey[0]) || (! pkey[1]) || (! pkey[2]))
792
err = GPG_ERR_BAD_MPI;
793
else
794
{
795
pk.p = pkey[0];
796
pk.g = pkey[1];
797
pk.y = pkey[2];
798
if (! verify (data[0], data[1], hash, &pk))
799
err = GPG_ERR_BAD_SIGNATURE;
800
}
801
802
return err;
803
}
804
805
806
static unsigned int
807
elg_get_nbits (int algo, gcry_mpi_t *pkey)
808
{
809
(void)algo;
810
811
return mpi_get_nbits (pkey[0]);
812
}
813
814
815
static const char *elg_names[] =
816
{
817
"elg",
818
"openpgp-elg",
819
"openpgp-elg-sig",
820
NULL,
821
};
822
823
824
gcry_pk_spec_t _gcry_pubkey_spec_elg =
825
{
826
"ELG", elg_names,
827
"pgy", "pgyx", "ab", "rs", "pgy",
828
GCRY_PK_USAGE_SIGN | GCRY_PK_USAGE_ENCR,
829
elg_generate,
830
elg_check_secret_key,
831
elg_encrypt,
832
elg_decrypt,
833
elg_sign,
834
elg_verify,
835
elg_get_nbits
836
};
837
838
pk_extra_spec_t _gcry_pubkey_extraspec_elg =
839
{
840
NULL,
841
elg_generate_ext,
842
NULL
843
};
844
Loggerhead is a web-based interface for Breezy
Version: 2.0.1