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comparison libtomcrypt/src/pk/katja/katja_make_key.c @ 398:59c7938af2bd

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merge of '1250b8af44b62d8f4fe0f8d9fc7e7a1cc34e7e1c' and '7f8670ac3bb975f40967f3979d09d2199b7e90c8'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:30 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
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396:e7c1a77d2921 398:59c7938af2bd
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file katja_make_key.c
15 Katja key generation, Tom St Denis
16 */
17
18 #ifdef MKAT
19
20 /**
21 Create a Katja key
22 @param prng An active PRNG state
23 @param wprng The index of the PRNG desired
24 @param size The size of the modulus (key size) desired (octets)
25 @param key [out] Destination of a newly created private key pair
26 @return CRYPT_OK if successful, upon error all allocated ram is freed
27 */
28 int katja_make_key(prng_state *prng, int wprng, int size, katja_key *key)
29 {
30 void *p, *q, *tmp1, *tmp2;
31 int err;
32
33 LTC_ARGCHK(key != NULL);
34 LTC_ARGCHK(ltc_mp.name != NULL);
35
36 if ((size < (MIN_KAT_SIZE/8)) || (size > (MAX_KAT_SIZE/8))) {
37 return CRYPT_INVALID_KEYSIZE;
38 }
39
40 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
41 return err;
42 }
43
44 if ((err = mp_init_multi(&p, &q, &tmp1, &tmp2, NULL)) != CRYPT_OK) {
45 return err;
46 }
47
48 /* divide size by three */
49 size = (((size << 3) / 3) + 7) >> 3;
50
51 /* make prime "q" (we negate size to make q == 3 mod 4) */
52 if ((err = rand_prime(q, -size, prng, wprng)) != CRYPT_OK) { goto done; }
53 if ((err = mp_sub_d(q, 1, tmp1)) != CRYPT_OK) { goto done; }
54
55 /* make prime "p" */
56 do {
57 if ((err = rand_prime(p, size+1, prng, wprng)) != CRYPT_OK) { goto done; }
58 if ((err = mp_gcd(p, tmp1, tmp2)) != CRYPT_OK) { goto done; }
59 } while (mp_cmp_d(tmp2, 1) != LTC_MP_EQ);
60
61 /* make key */
62 if ((err = mp_init_multi(&key->d, &key->N, &key->dQ, &key->dP,
63 &key->qP, &key->p, &key->q, &key->pq, NULL)) != CRYPT_OK) {
64 goto error;
65 }
66
67 /* n=p^2q and 1/n mod pq */
68 if ((err = mp_copy( p, key->p)) != CRYPT_OK) { goto error2; }
69 if ((err = mp_copy( q, key->q)) != CRYPT_OK) { goto error2; }
70 if ((err = mp_mul(key->p, key->q, key->pq)) != CRYPT_OK) { goto error2; } /* tmp1 = pq */
71 if ((err = mp_mul(key->pq, key->p, key->N)) != CRYPT_OK) { goto error2; } /* N = p^2q */
72 if ((err = mp_sub_d( p, 1, tmp1)) != CRYPT_OK) { goto error2; } /* tmp1 = q-1 */
73 if ((err = mp_sub_d( q, 1, tmp2)) != CRYPT_OK) { goto error2; } /* tmp2 = p-1 */
74 if ((err = mp_lcm(tmp1, tmp2, key->d)) != CRYPT_OK) { goto error2; } /* tmp1 = lcd(p-1,q-1) */
75 if ((err = mp_invmod( key->N, key->d, key->d)) != CRYPT_OK) { goto error2; } /* key->d = 1/N mod pq */
76
77 /* optimize for CRT now */
78 /* find d mod q-1 and d mod p-1 */
79 if ((err = mp_mod( key->d, tmp1, key->dP)) != CRYPT_OK) { goto error2; } /* dP = d mod p-1 */
80 if ((err = mp_mod( key->d, tmp2, key->dQ)) != CRYPT_OK) { goto error2; } /* dQ = d mod q-1 */
81 if ((err = mp_invmod( q, p, key->qP)) != CRYPT_OK) { goto error2; } /* qP = 1/q mod p */
82
83 /* set key type (in this case it's CRT optimized) */
84 key->type = PK_PRIVATE;
85
86 /* return ok and free temps */
87 err = CRYPT_OK;
88 goto done;
89 error2:
90 mp_clear_multi( key->d, key->N, key->dQ, key->dP, key->qP, key->p, key->q, key->pq, NULL);
91 error:
92 done:
93 mp_clear_multi( tmp2, tmp1, p, q, NULL);
94 return err;
95 }
96
97 #endif
98
99 /* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_make_key.c,v $ */
100 /* $Revision: 1.10 $ */
101 /* $Date: 2006/03/31 14:15:35 $ */