4 This file is part of the ARM-Crypto-Lib.
5 Copyright (C) 2006-2012 Daniel Otte (daniel.otte@rub.de)
7 This program is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
27 #include "rsa_basic.h"
30 #include "random_dummy.h"
32 #include "hfal/hfal_sha1.h"
34 mgf1_parameter_t mgf1_default_parameter = {
38 rsa_oaep_parameter_t rsa_oaep_default_parameter = {
41 &mgf1_default_parameter
44 rsa_label_t rsa_oaep_default_label = {
48 uint8_t rsa_encrypt_oaep(void* dest, uint16_t* out_length,
49 const void* src, uint16_t length_B,
50 rsa_publickey_t* key, const rsa_oaep_parameter_t *p,
51 const rsa_label_t* label, const void* seed){
54 p = &rsa_oaep_default_parameter;
57 label = &rsa_oaep_default_label;
59 uint16_t hv_len = (hfal_hash_getHashsize(p->hf)+7)/8;
60 if(length_B > bigint_length_B(key->modulus) - 2*hv_len - 2){
61 /* message too long */
64 uint16_t buffer_len = bigint_length_B(key->modulus);
65 uint8_t* buffer = (uint8_t*)dest;
67 /* the following needs some explanation:
68 * off is the offset which is used for compensating the effect of
69 * changeendian() when it operates on multi-byte words.
71 off = (sizeof(bigint_word_t) -(bigint_get_first_set_bit(key->modulus)/8+1)%(sizeof(bigint_word_t)*8))
72 % (sizeof(bigint_word_t));
75 uint8_t* seed_buffer = buffer + 1;
76 uint16_t db_len = buffer_len - hv_len - 1;
77 uint8_t* db = seed_buffer + hv_len;
78 uint16_t maskbuffer_len = db_len>hv_len?db_len:hv_len;
79 uint8_t maskbuffer[maskbuffer_len];
82 memset(buffer, 0, seed_buffer - buffer);
83 memset(db + hv_len, 0, db_len - hv_len - length_B -1);
84 hfal_hash_mem(p->hf, db, label->label, label->length_b);
85 db[db_len - length_B - 1] = 0x01;
86 memcpy(db+db_len - length_B, src, length_B);
88 memcpy(seed_buffer, seed, hv_len);
90 /* generate random seed */
92 return 2; /* ERROR: no random generator specified */
95 for(i=0; i<hv_len; ++i){
96 seed_buffer[i] = prng_get_byte();
100 p->mgf(maskbuffer, seed_buffer, hv_len, db_len, p->mgf_parameter);
101 memxor(db, maskbuffer, db_len);
102 p->mgf(maskbuffer, db, db_len, hv_len, p->mgf_parameter);
103 memxor(seed_buffer, maskbuffer, hv_len);
106 x.length_B = key->modulus->length_B;
109 rsa_os2ip(&x, NULL, bigint_length_B(key->modulus));
111 rsa_i2osp(NULL, &x, out_length);
115 uint8_t rsa_decrypt_oaep(void* dest, uint16_t* out_length,
116 const void* src, uint16_t length_B,
117 rsa_privatekey_t* key, const rsa_oaep_parameter_t *p,
118 const rsa_label_t* label, void* seed){
121 label = &rsa_oaep_default_label;
124 p = &rsa_oaep_default_parameter;
126 uint8_t *buffer = dest;
127 uint16_t x_len, data_len;
129 uint16_t hv_len = hfal_hash_getHashsize(p->hf)/8;
130 uint8_t label_hv[hv_len];
131 uint16_t msg_len = (bigint_get_first_set_bit(key->modulus)+7)/8;
132 uint16_t db_len = msg_len - 1 - hv_len;
133 uint8_t maskbuffer[db_len>hv_len?db_len:hv_len];
135 uint8_t *seed_buffer = buffer + 1;
136 uint8_t *db_buffer = seed_buffer + hv_len;
138 x_len = bigint_length_B(key->modulus);
139 memset(dest, 0, x_len - length_B);
140 buffer = (uint8_t*)dest + x_len - length_B;
141 memcpy(buffer, src, length_B);
144 x.length_B = key->modulus->length_B;
147 rsa_os2ip(&x, NULL, bigint_length_B(key->modulus));
149 rsa_i2osp(NULL, &x, &data_len);
151 if(data_len != x_len){
152 memmove(buffer + x_len - data_len, buffer, data_len);
153 memset(buffer, 0, x_len - data_len);
156 if(data_len > msg_len){
160 memmove(buffer + msg_len - data_len, buffer, data_len);
162 hfal_hash_mem(p->hf, label_hv, label->label, label->length_b);
168 p->mgf(maskbuffer, db_buffer, db_len, hv_len, p->mgf_parameter);
169 memxor(seed_buffer, maskbuffer, hv_len);
170 p->mgf(maskbuffer, seed_buffer, hv_len, db_len, p->mgf_parameter);
171 memxor(db_buffer, maskbuffer, db_len);
173 if(memcmp(label_hv, db_buffer, hv_len)){
178 while(db_buffer[hv_len + ps_len++] == 0)
182 if(db_buffer[hv_len + ps_len] != 1){
187 memcpy(seed, seed_buffer, hv_len);
190 msg_len = db_len - hv_len - 1 - ps_len;
191 memmove(dest, db_buffer + hv_len + ps_len + 1, msg_len);
193 *out_length = msg_len;