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comparison genrsa.c @ 892:ae766a2c8fa7

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generate RSA keys of exact length
author Matt Johnston <matt@ucc.asn.au>
date Fri, 14 Feb 2014 23:18:45 +0800
parents 220f55d540ae
children 750ec4ec4cbe
comparison
equal deleted inserted replaced
891:e78f5ce6e7bb 892:ae766a2c8fa7
56 if (mp_set_int(key->e, RSA_E) != MP_OKAY) { 56 if (mp_set_int(key->e, RSA_E) != MP_OKAY) {
57 fprintf(stderr, "RSA generation failed\n"); 57 fprintf(stderr, "RSA generation failed\n");
58 exit(1); 58 exit(1);
59 } 59 }
60 60
61 getrsaprime(key->p, &pminus, key->e, size/16); 61 while (1) {
62 getrsaprime(key->q, &qminus, key->e, size/16); 62 getrsaprime(key->p, &pminus, key->e, size/16);
63 getrsaprime(key->q, &qminus, key->e, size/16);
63 64
64 if (mp_mul(key->p, key->q, key->n) != MP_OKAY) { 65 if (mp_mul(key->p, key->q, key->n) != MP_OKAY) {
65 fprintf(stderr, "RSA generation failed\n"); 66 fprintf(stderr, "RSA generation failed\n");
66 exit(1); 67 exit(1);
68 }
69
70 if ((unsigned int)mp_count_bits(key->n) == size) {
71 break;
72 }
67 } 73 }
68 74
69 /* lcm(p-1, q-1) */ 75 /* lcm(p-1, q-1) */
70 if (mp_lcm(&pminus, &qminus, &lcm) != MP_OKAY) { 76 if (mp_lcm(&pminus, &qminus, &lcm) != MP_OKAY) {
71 fprintf(stderr, "RSA generation failed\n"); 77 fprintf(stderr, "RSA generation failed\n");
89 mp_int* rsa_e, unsigned int size_bytes) { 95 mp_int* rsa_e, unsigned int size_bytes) {
90 96
91 unsigned char *buf; 97 unsigned char *buf;
92 DEF_MP_INT(temp_gcd); 98 DEF_MP_INT(temp_gcd);
93 99
94 buf = (unsigned char*)m_malloc(size_bytes+1); 100 buf = (unsigned char*)m_malloc(size_bytes);
95 101
96 m_mp_init(&temp_gcd); 102 m_mp_init(&temp_gcd);
97 do { 103 do {
98 /* generate a random odd number with MSB set, then find the 104 /* generate a random odd number with MSB set, then find the
99 the next prime above it */ 105 the next prime above it */
100 genrandom(buf, size_bytes+1); 106 genrandom(buf, size_bytes);
101 buf[0] |= 0x80; /* MSB set */ 107 buf[0] |= 0x80;
102 108
103 bytes_to_mp(prime, buf, size_bytes+1); 109 bytes_to_mp(prime, buf, size_bytes);
104 110
105 /* find the next integer which is prime, 8 round of miller-rabin */ 111 /* find the next integer which is prime, 8 round of miller-rabin */
106 if (mp_prime_next_prime(prime, 8, 0) != MP_OKAY) { 112 if (mp_prime_next_prime(prime, 8, 0) != MP_OKAY) {
107 fprintf(stderr, "RSA generation failed\n"); 113 fprintf(stderr, "RSA generation failed\n");
108 exit(1); 114 exit(1);
120 } 126 }
121 } while (mp_cmp_d(&temp_gcd, 1) != MP_EQ); /* while gcd(p-1, e) != 1 */ 127 } while (mp_cmp_d(&temp_gcd, 1) != MP_EQ); /* while gcd(p-1, e) != 1 */
122 128
123 /* now we have a good value for result */ 129 /* now we have a good value for result */
124 mp_clear(&temp_gcd); 130 mp_clear(&temp_gcd);
125 m_burn(buf, size_bytes+1); 131 m_burn(buf, size_bytes);
126 m_free(buf); 132 m_free(buf);
127 } 133 }
128 134
129 #endif /* DROPBEAR_RSA */ 135 #endif /* DROPBEAR_RSA */