2 * Copyright (c) 2007, Cameron Rich
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
9 * * Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 * * Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 * * Neither the name of the axTLS project nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
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19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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32 * Implements the RSA public encryption algorithm. Uses the bigint library to
33 * perform its calculations.
42 void RSA_priv_key_new(RSA_CTX **ctx,
43 const uint8_t *modulus, int mod_len,
44 const uint8_t *pub_exp, int pub_len,
45 const uint8_t *priv_exp, int priv_len
47 , const uint8_t *p, int p_len,
48 const uint8_t *q, int q_len,
49 const uint8_t *dP, int dP_len,
50 const uint8_t *dQ, int dQ_len,
51 const uint8_t *qInv, int qInv_len
57 RSA_pub_key_new(ctx, modulus, mod_len, pub_exp, pub_len);
59 bi_ctx = rsa_ctx->bi_ctx;
60 rsa_ctx->d = bi_import(bi_ctx, priv_exp, priv_len);
61 bi_permanent(rsa_ctx->d);
63 #ifdef CONFIG_BIGINT_CRT
64 rsa_ctx->p = bi_import(bi_ctx, p, p_len);
65 rsa_ctx->q = bi_import(bi_ctx, q, q_len);
66 rsa_ctx->dP = bi_import(bi_ctx, dP, dP_len);
67 rsa_ctx->dQ = bi_import(bi_ctx, dQ, dQ_len);
68 rsa_ctx->qInv = bi_import(bi_ctx, qInv, qInv_len);
69 bi_permanent(rsa_ctx->dP);
70 bi_permanent(rsa_ctx->dQ);
71 bi_permanent(rsa_ctx->qInv);
72 bi_set_mod(bi_ctx, rsa_ctx->p, BIGINT_P_OFFSET);
73 bi_set_mod(bi_ctx, rsa_ctx->q, BIGINT_Q_OFFSET);
77 void RSA_pub_key_new(RSA_CTX **ctx,
78 const uint8_t *modulus, int mod_len,
79 const uint8_t *pub_exp, int pub_len)
84 if (*ctx) /* if we load multiple certs, dump the old one */
87 bi_ctx = bi_initialize();
88 *ctx = (RSA_CTX *)calloc(1, sizeof(RSA_CTX));
90 rsa_ctx->bi_ctx = bi_ctx;
91 rsa_ctx->num_octets = (mod_len & 0xFFF0);
92 rsa_ctx->m = bi_import(bi_ctx, modulus, mod_len);
93 bi_set_mod(bi_ctx, rsa_ctx->m, BIGINT_M_OFFSET);
94 rsa_ctx->e = bi_import(bi_ctx, pub_exp, pub_len);
95 bi_permanent(rsa_ctx->e);
99 * Free up any RSA context resources.
101 void RSA_free(RSA_CTX *rsa_ctx)
104 if (rsa_ctx == NULL) /* deal with ptrs that are null */
107 bi_ctx = rsa_ctx->bi_ctx;
109 bi_depermanent(rsa_ctx->e);
110 bi_free(bi_ctx, rsa_ctx->e);
111 bi_free_mod(rsa_ctx->bi_ctx, BIGINT_M_OFFSET);
115 bi_depermanent(rsa_ctx->d);
116 bi_free(bi_ctx, rsa_ctx->d);
117 #ifdef CONFIG_BIGINT_CRT
118 bi_depermanent(rsa_ctx->dP);
119 bi_depermanent(rsa_ctx->dQ);
120 bi_depermanent(rsa_ctx->qInv);
121 bi_free(bi_ctx, rsa_ctx->dP);
122 bi_free(bi_ctx, rsa_ctx->dQ);
123 bi_free(bi_ctx, rsa_ctx->qInv);
124 bi_free_mod(rsa_ctx->bi_ctx, BIGINT_P_OFFSET);
125 bi_free_mod(rsa_ctx->bi_ctx, BIGINT_Q_OFFSET);
129 bi_terminate(bi_ctx);
134 * @brief Use PKCS1.5 for decryption/verification.
135 * @param ctx [in] The context
136 * @param in_data [in] The data to encrypt (must be < modulus size-11)
137 * @param out_data [out] The encrypted data.
138 * @param is_decryption [in] Decryption or verify operation.
139 * @return The number of bytes that were originally encrypted. -1 on error.
140 * @see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
142 int RSA_decrypt(const RSA_CTX *ctx, const uint8_t *in_data,
143 uint8_t *out_data, int is_decryption)
145 const int byte_size = ctx->num_octets;
147 bigint *decrypted_bi, *dat_bi;
148 uint8_t *block = (uint8_t *)alloca(byte_size);
150 memset(out_data, 0, byte_size); /* initialise */
153 dat_bi = bi_import(ctx->bi_ctx, in_data, byte_size);
154 #ifdef CONFIG_SSL_CERT_VERIFICATION
155 decrypted_bi = is_decryption ? /* decrypt or verify? */
156 RSA_private(ctx, dat_bi) : RSA_public(ctx, dat_bi);
157 #else /* always a decryption */
158 decrypted_bi = RSA_private(ctx, dat_bi);
161 /* convert to a normal block */
162 bi_export(ctx->bi_ctx, decrypted_bi, block, byte_size);
164 i = 10; /* start at the first possible non-padded byte */
166 #ifdef CONFIG_SSL_CERT_VERIFICATION
167 if (is_decryption == 0) /* PKCS1.5 signing pads with "0xff"s */
169 while (block[i++] == 0xff && i < byte_size);
171 if (block[i-2] != 0xff)
172 i = byte_size; /*ensure size is 0 */
174 else /* PKCS1.5 encryption padding is random */
177 while (block[i++] && i < byte_size);
179 size = byte_size - i;
181 /* get only the bit we want */
183 memcpy(out_data, &block[i], size);
185 return size ? size : -1;
189 * Performs m = c^d mod n
191 bigint *RSA_private(const RSA_CTX *c, bigint *bi_msg)
193 #ifdef CONFIG_BIGINT_CRT
194 return bi_crt(c->bi_ctx, bi_msg, c->dP, c->dQ, c->p, c->q, c->qInv);
196 BI_CTX *ctx = c->bi_ctx;
197 ctx->mod_offset = BIGINT_M_OFFSET;
198 return bi_mod_power(ctx, bi_msg, c->d);
202 #ifdef CONFIG_SSL_FULL_MODE
204 * Used for diagnostics.
206 void RSA_print(const RSA_CTX *rsa_ctx)
211 printf("----------------- RSA DEBUG ----------------\n");
212 printf("Size:\t%d\n", rsa_ctx->num_octets);
213 bi_print("Modulus", rsa_ctx->m);
214 bi_print("Public Key", rsa_ctx->e);
215 bi_print("Private Key", rsa_ctx->d);
219 #if defined(CONFIG_SSL_CERT_VERIFICATION) || defined(CONFIG_SSL_GENERATE_X509_CERT)
221 * Performs c = m^e mod n
223 bigint *RSA_public(const RSA_CTX * c, bigint *bi_msg)
225 c->bi_ctx->mod_offset = BIGINT_M_OFFSET;
226 return bi_mod_power(c->bi_ctx, bi_msg, c->e);
230 * Use PKCS1.5 for encryption/signing.
231 * see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
233 int RSA_encrypt(const RSA_CTX *ctx, const uint8_t *in_data, uint16_t in_len,
234 uint8_t *out_data, int is_signing)
236 int byte_size = ctx->num_octets;
237 int num_pads_needed = byte_size-in_len-3;
238 bigint *dat_bi, *encrypt_bi;
240 /* note: in_len+11 must be > byte_size */
241 out_data[0] = 0; /* ensure encryption block is < modulus */
245 out_data[1] = 1; /* PKCS1.5 signing pads with "0xff"'s */
246 memset(&out_data[2], 0xff, num_pads_needed);
248 else /* randomize the encryption padding with non-zero bytes */
251 get_random_NZ(num_pads_needed, &out_data[2]);
254 out_data[2+num_pads_needed] = 0;
255 memcpy(&out_data[3+num_pads_needed], in_data, in_len);
258 dat_bi = bi_import(ctx->bi_ctx, out_data, byte_size);
259 encrypt_bi = is_signing ? RSA_private(ctx, dat_bi) :
260 RSA_public(ctx, dat_bi);
261 bi_export(ctx->bi_ctx, encrypt_bi, out_data, byte_size);
263 /* save a few bytes of memory */
264 bi_clear_cache(ctx->bi_ctx);
268 #endif /* CONFIG_SSL_CERT_VERIFICATION */