Annotation of embedaddon/axTLS/crypto/rsa.c, revision 1.1.1.1
1.1 misho 1: /*
2: * Copyright (c) 2007, Cameron Rich
3: *
4: * All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions are met:
8: *
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.
17: *
18: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
22: * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24: * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
25: * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
26: * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
27: * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28: * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29: */
30:
31: /**
32: * Implements the RSA public encryption algorithm. Uses the bigint library to
33: * perform its calculations.
34: */
35:
36: #include <stdio.h>
37: #include <string.h>
38: #include <time.h>
39: #include <stdlib.h>
40: #include "os_port.h"
41: #include "crypto.h"
42:
43: void RSA_priv_key_new(RSA_CTX **ctx,
44: const uint8_t *modulus, int mod_len,
45: const uint8_t *pub_exp, int pub_len,
46: const uint8_t *priv_exp, int priv_len
47: #if CONFIG_BIGINT_CRT
48: , const uint8_t *p, int p_len,
49: const uint8_t *q, int q_len,
50: const uint8_t *dP, int dP_len,
51: const uint8_t *dQ, int dQ_len,
52: const uint8_t *qInv, int qInv_len
53: #endif
54: )
55: {
56: RSA_CTX *rsa_ctx;
57: BI_CTX *bi_ctx;
58: RSA_pub_key_new(ctx, modulus, mod_len, pub_exp, pub_len);
59: rsa_ctx = *ctx;
60: bi_ctx = rsa_ctx->bi_ctx;
61: rsa_ctx->d = bi_import(bi_ctx, priv_exp, priv_len);
62: bi_permanent(rsa_ctx->d);
63:
64: #ifdef CONFIG_BIGINT_CRT
65: rsa_ctx->p = bi_import(bi_ctx, p, p_len);
66: rsa_ctx->q = bi_import(bi_ctx, q, q_len);
67: rsa_ctx->dP = bi_import(bi_ctx, dP, dP_len);
68: rsa_ctx->dQ = bi_import(bi_ctx, dQ, dQ_len);
69: rsa_ctx->qInv = bi_import(bi_ctx, qInv, qInv_len);
70: bi_permanent(rsa_ctx->dP);
71: bi_permanent(rsa_ctx->dQ);
72: bi_permanent(rsa_ctx->qInv);
73: bi_set_mod(bi_ctx, rsa_ctx->p, BIGINT_P_OFFSET);
74: bi_set_mod(bi_ctx, rsa_ctx->q, BIGINT_Q_OFFSET);
75: #endif
76: }
77:
78: void RSA_pub_key_new(RSA_CTX **ctx,
79: const uint8_t *modulus, int mod_len,
80: const uint8_t *pub_exp, int pub_len)
81: {
82: RSA_CTX *rsa_ctx;
83: BI_CTX *bi_ctx;
84:
85: if (*ctx) /* if we load multiple certs, dump the old one */
86: RSA_free(*ctx);
87:
88: bi_ctx = bi_initialize();
89: *ctx = (RSA_CTX *)calloc(1, sizeof(RSA_CTX));
90: rsa_ctx = *ctx;
91: rsa_ctx->bi_ctx = bi_ctx;
92: rsa_ctx->num_octets = mod_len;
93: rsa_ctx->m = bi_import(bi_ctx, modulus, mod_len);
94: bi_set_mod(bi_ctx, rsa_ctx->m, BIGINT_M_OFFSET);
95: rsa_ctx->e = bi_import(bi_ctx, pub_exp, pub_len);
96: bi_permanent(rsa_ctx->e);
97: }
98:
99: /**
100: * Free up any RSA context resources.
101: */
102: void RSA_free(RSA_CTX *rsa_ctx)
103: {
104: BI_CTX *bi_ctx;
105: if (rsa_ctx == NULL) /* deal with ptrs that are null */
106: return;
107:
108: bi_ctx = rsa_ctx->bi_ctx;
109:
110: bi_depermanent(rsa_ctx->e);
111: bi_free(bi_ctx, rsa_ctx->e);
112: bi_free_mod(rsa_ctx->bi_ctx, BIGINT_M_OFFSET);
113:
114: if (rsa_ctx->d)
115: {
116: bi_depermanent(rsa_ctx->d);
117: bi_free(bi_ctx, rsa_ctx->d);
118: #ifdef CONFIG_BIGINT_CRT
119: bi_depermanent(rsa_ctx->dP);
120: bi_depermanent(rsa_ctx->dQ);
121: bi_depermanent(rsa_ctx->qInv);
122: bi_free(bi_ctx, rsa_ctx->dP);
123: bi_free(bi_ctx, rsa_ctx->dQ);
124: bi_free(bi_ctx, rsa_ctx->qInv);
125: bi_free_mod(rsa_ctx->bi_ctx, BIGINT_P_OFFSET);
126: bi_free_mod(rsa_ctx->bi_ctx, BIGINT_Q_OFFSET);
127: #endif
128: }
129:
130: bi_terminate(bi_ctx);
131: free(rsa_ctx);
132: }
133:
134: /**
135: * @brief Use PKCS1.5 for decryption/verification.
136: * @param ctx [in] The context
137: * @param in_data [in] The data to encrypt (must be < modulus size-11)
138: * @param out_data [out] The encrypted data.
139: * @param is_decryption [in] Decryption or verify operation.
140: * @return The number of bytes that were originally encrypted. -1 on error.
141: * @see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
142: */
143: int RSA_decrypt(const RSA_CTX *ctx, const uint8_t *in_data,
144: uint8_t *out_data, int is_decryption)
145: {
146: const int byte_size = ctx->num_octets;
147: int i, size;
148: bigint *decrypted_bi, *dat_bi;
149: uint8_t *block = (uint8_t *)alloca(byte_size);
150:
151: memset(out_data, 0, byte_size); /* initialise */
152:
153: /* decrypt */
154: dat_bi = bi_import(ctx->bi_ctx, in_data, byte_size);
155: #ifdef CONFIG_SSL_CERT_VERIFICATION
156: decrypted_bi = is_decryption ? /* decrypt or verify? */
157: RSA_private(ctx, dat_bi) : RSA_public(ctx, dat_bi);
158: #else /* always a decryption */
159: decrypted_bi = RSA_private(ctx, dat_bi);
160: #endif
161:
162: /* convert to a normal block */
163: bi_export(ctx->bi_ctx, decrypted_bi, block, byte_size);
164:
165: i = 10; /* start at the first possible non-padded byte */
166:
167: #ifdef CONFIG_SSL_CERT_VERIFICATION
168: if (is_decryption == 0) /* PKCS1.5 signing pads with "0xff"s */
169: {
170: while (block[i++] == 0xff && i < byte_size);
171:
172: if (block[i-2] != 0xff)
173: i = byte_size; /*ensure size is 0 */
174: }
175: else /* PKCS1.5 encryption padding is random */
176: #endif
177: {
178: while (block[i++] && i < byte_size);
179: }
180: size = byte_size - i;
181:
182: /* get only the bit we want */
183: if (size > 0)
184: memcpy(out_data, &block[i], size);
185:
186: return size ? size : -1;
187: }
188:
189: /**
190: * Performs m = c^d mod n
191: */
192: bigint *RSA_private(const RSA_CTX *c, bigint *bi_msg)
193: {
194: #ifdef CONFIG_BIGINT_CRT
195: return bi_crt(c->bi_ctx, bi_msg, c->dP, c->dQ, c->p, c->q, c->qInv);
196: #else
197: BI_CTX *ctx = c->bi_ctx;
198: ctx->mod_offset = BIGINT_M_OFFSET;
199: return bi_mod_power(ctx, bi_msg, c->d);
200: #endif
201: }
202:
203: #ifdef CONFIG_SSL_FULL_MODE
204: /**
205: * Used for diagnostics.
206: */
207: void RSA_print(const RSA_CTX *rsa_ctx)
208: {
209: if (rsa_ctx == NULL)
210: return;
211:
212: printf("----------------- RSA DEBUG ----------------\n");
213: printf("Size:\t%d\n", rsa_ctx->num_octets);
214: bi_print("Modulus", rsa_ctx->m);
215: bi_print("Public Key", rsa_ctx->e);
216: bi_print("Private Key", rsa_ctx->d);
217: }
218: #endif
219:
220: #if defined(CONFIG_SSL_CERT_VERIFICATION) || defined(CONFIG_SSL_GENERATE_X509_CERT)
221: /**
222: * Performs c = m^e mod n
223: */
224: bigint *RSA_public(const RSA_CTX * c, bigint *bi_msg)
225: {
226: c->bi_ctx->mod_offset = BIGINT_M_OFFSET;
227: return bi_mod_power(c->bi_ctx, bi_msg, c->e);
228: }
229:
230: /**
231: * Use PKCS1.5 for encryption/signing.
232: * see http://www.rsasecurity.com/rsalabs/node.asp?id=2125
233: */
234: int RSA_encrypt(const RSA_CTX *ctx, const uint8_t *in_data, uint16_t in_len,
235: uint8_t *out_data, int is_signing)
236: {
237: int byte_size = ctx->num_octets;
238: int num_pads_needed = byte_size-in_len-3;
239: bigint *dat_bi, *encrypt_bi;
240:
241: /* note: in_len+11 must be > byte_size */
242: out_data[0] = 0; /* ensure encryption block is < modulus */
243:
244: if (is_signing)
245: {
246: out_data[1] = 1; /* PKCS1.5 signing pads with "0xff"'s */
247: memset(&out_data[2], 0xff, num_pads_needed);
248: }
249: else /* randomize the encryption padding with non-zero bytes */
250: {
251: out_data[1] = 2;
252: get_random_NZ(num_pads_needed, &out_data[2]);
253: }
254:
255: out_data[2+num_pads_needed] = 0;
256: memcpy(&out_data[3+num_pads_needed], in_data, in_len);
257:
258: /* now encrypt it */
259: dat_bi = bi_import(ctx->bi_ctx, out_data, byte_size);
260: encrypt_bi = is_signing ? RSA_private(ctx, dat_bi) :
261: RSA_public(ctx, dat_bi);
262: bi_export(ctx->bi_ctx, encrypt_bi, out_data, byte_size);
263:
264: /* save a few bytes of memory */
265: bi_clear_cache(ctx->bi_ctx);
266: return byte_size;
267: }
268:
269: #endif /* CONFIG_SSL_CERT_VERIFICATION */
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