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comparison rsa_exptmod.c @ 15:6362d3854bb4 libtomcrypt-orig

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0.96 release of LibTomCrypt
author Matt Johnston <matt@ucc.asn.au>
date Tue, 15 Jun 2004 14:07:21 +0000
parents 7faae8f46238
children 5d99163f7e32
comparison
equal deleted inserted replaced
3:7faae8f46238 15:6362d3854bb4
12 /* RSA Code by Tom St Denis */ 12 /* RSA Code by Tom St Denis */
13 #include "mycrypt.h" 13 #include "mycrypt.h"
14 14
15 #ifdef MRSA 15 #ifdef MRSA
16 16
17 int rsa_exptmod(const unsigned char *in, unsigned long inlen, 17 int rsa_exptmod(const unsigned char *in, unsigned long inlen,
18 unsigned char *out, unsigned long *outlen, int which, 18 unsigned char *out, unsigned long *outlen, int which,
19 prng_state *prng, int prng_idx,
19 rsa_key *key) 20 rsa_key *key)
20 { 21 {
21 mp_int tmp, tmpa, tmpb; 22 mp_int tmp, tmpa, tmpb;
22 unsigned long x; 23 unsigned long x;
23 int err; 24 int err;
24 25
25 _ARGCHK(in != NULL); 26 _ARGCHK(in != NULL);
26 _ARGCHK(out != NULL); 27 _ARGCHK(out != NULL);
27 _ARGCHK(outlen != NULL); 28 _ARGCHK(outlen != NULL);
28 _ARGCHK(key != NULL); 29 _ARGCHK(key != NULL);
30
31 if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
32 return err;
33 }
29 34
30 if (which == PK_PRIVATE && (key->type != PK_PRIVATE && key->type != PK_PRIVATE_OPTIMIZED)) { 35 if (which == PK_PRIVATE && (key->type != PK_PRIVATE && key->type != PK_PRIVATE_OPTIMIZED)) {
31 return CRYPT_PK_NOT_PRIVATE; 36 return CRYPT_PK_NOT_PRIVATE;
32 } 37 }
33 38
47 } 52 }
48 53
49 /* are we using the private exponent and is the key optimized? */ 54 /* are we using the private exponent and is the key optimized? */
50 if (which == PK_PRIVATE && key->type == PK_PRIVATE_OPTIMIZED) { 55 if (which == PK_PRIVATE && key->type == PK_PRIVATE_OPTIMIZED) {
51 /* tmpa = tmp^dP mod p */ 56 /* tmpa = tmp^dP mod p */
52 if ((err = mp_exptmod(&tmp, &key->dP, &key->p, &tmpa)) != MP_OKAY) { goto error; } 57 if ((err = tim_exptmod(prng, prng_idx, &tmp, &key->e, &key->dP, &key->p, &tmpa)) != MP_OKAY) { goto error; }
53 58
54 /* tmpb = tmp^dQ mod q */ 59 /* tmpb = tmp^dQ mod q */
55 if ((err = mp_exptmod(&tmp, &key->dQ, &key->q, &tmpb)) != MP_OKAY) { goto error; } 60 if ((err = tim_exptmod(prng, prng_idx, &tmp, &key->e, &key->dQ, &key->q, &tmpb)) != MP_OKAY) { goto error; }
56 61
57 /* tmp = tmpa*qP + tmpb*pQ mod N */ 62 /* tmp = tmpa*qP + tmpb*pQ mod N */
58 if ((err = mp_mul(&tmpa, &key->qP, &tmpa)) != MP_OKAY) { goto error; } 63 if ((err = mp_mul(&tmpa, &key->qP, &tmpa)) != MP_OKAY) { goto error; }
59 if ((err = mp_mul(&tmpb, &key->pQ, &tmpb)) != MP_OKAY) { goto error; } 64 if ((err = mp_mul(&tmpb, &key->pQ, &tmpb)) != MP_OKAY) { goto error; }
60 if ((err = mp_addmod(&tmpa, &tmpb, &key->N, &tmp)) != MP_OKAY) { goto error; } 65 if ((err = mp_addmod(&tmpa, &tmpb, &key->N, &tmp)) != MP_OKAY) { goto error; }
61 } else { 66 } else {
62 /* exptmod it */ 67 /* exptmod it */
63 if ((err = mp_exptmod(&tmp, which==PK_PRIVATE?&key->d:&key->e, &key->N, &tmp)) != MP_OKAY) { goto error; } 68 if (which == PK_PRIVATE) {
69 if ((err = tim_exptmod(prng, prng_idx, &tmp, &key->e, &key->d, &key->N, &tmp)) != MP_OKAY) { goto error; }
70 } else {
71 if ((err = mp_exptmod(&tmp, &key->e, &key->N, &tmp)) != MP_OKAY) { goto error; }
72 }
64 } 73 }
65 74
66 /* read it back */ 75 /* read it back */
67 x = (unsigned long)mp_unsigned_bin_size(&tmp); 76 x = (unsigned long)mp_unsigned_bin_size(&key->N);
68 if (x > *outlen) { 77 if (x > *outlen) {
69 err = CRYPT_BUFFER_OVERFLOW; 78 err = CRYPT_BUFFER_OVERFLOW;
70 goto done; 79 goto done;
71 } 80 }
72 *outlen = x; 81 *outlen = x;
73 82
74 /* convert it */ 83 /* convert it */
75 if ((err = mp_to_unsigned_bin(&tmp, out)) != MP_OKAY) { goto error; } 84 zeromem(out, x);
85 if ((err = mp_to_unsigned_bin(&tmp, out+(x-mp_unsigned_bin_size(&tmp)))) != MP_OKAY) { goto error; }
76 86
77 /* clean up and return */ 87 /* clean up and return */
78 err = CRYPT_OK; 88 err = CRYPT_OK;
79 goto done; 89 goto done;
80 error: 90 error: