1 /* rsa_pss.c */
2 /* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
3 * project 2005.
4 */
5 /* ====================================================================
6 * Copyright (c) 2005 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * licensing@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58
59 #include <stdio.h>
60 #include "cryptlib.h"
61 #include <openssl/bn.h>
62 #include <openssl/rsa.h>
63 #include <openssl/evp.h>
64 #include <openssl/rand.h>
65 #include <openssl/sha.h>
66
67 const static unsigned char zeroes[] = {0,0,0,0,0,0,0,0};
68
RSA_verify_PKCS1_PSS(RSA * rsa,const unsigned char * mHash,const EVP_MD * Hash,const unsigned char * EM,int sLen)69 int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,
70 const EVP_MD *Hash, const unsigned char *EM, int sLen)
71 {
72 int i;
73 int ret = 0;
74 int hLen, maskedDBLen, MSBits, emLen;
75 const unsigned char *H;
76 unsigned char *DB = NULL;
77 EVP_MD_CTX ctx;
78 unsigned char H_[EVP_MAX_MD_SIZE];
79
80 hLen = EVP_MD_size(Hash);
81 /*
82 * Negative sLen has special meanings:
83 * -1 sLen == hLen
84 * -2 salt length is autorecovered from signature
85 * -N reserved
86 */
87 if (sLen == -1) sLen = hLen;
88 else if (sLen == -2) sLen = -2;
89 else if (sLen < -2)
90 {
91 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
92 goto err;
93 }
94
95 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
96 emLen = RSA_size(rsa);
97 if (EM[0] & (0xFF << MSBits))
98 {
99 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_FIRST_OCTET_INVALID);
100 goto err;
101 }
102 if (MSBits == 0)
103 {
104 EM++;
105 emLen--;
106 }
107 if (emLen < (hLen + sLen + 2)) /* sLen can be small negative */
108 {
109 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_DATA_TOO_LARGE);
110 goto err;
111 }
112 if (EM[emLen - 1] != 0xbc)
113 {
114 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_LAST_OCTET_INVALID);
115 goto err;
116 }
117 maskedDBLen = emLen - hLen - 1;
118 H = EM + maskedDBLen;
119 DB = OPENSSL_malloc(maskedDBLen);
120 if (!DB)
121 {
122 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, ERR_R_MALLOC_FAILURE);
123 goto err;
124 }
125 PKCS1_MGF1(DB, maskedDBLen, H, hLen, Hash);
126 for (i = 0; i < maskedDBLen; i++)
127 DB[i] ^= EM[i];
128 if (MSBits)
129 DB[0] &= 0xFF >> (8 - MSBits);
130 for (i = 0; DB[i] == 0 && i < (maskedDBLen-1); i++) ;
131 if (DB[i++] != 0x1)
132 {
133 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_RECOVERY_FAILED);
134 goto err;
135 }
136 if (sLen >= 0 && (maskedDBLen - i) != sLen)
137 {
138 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
139 goto err;
140 }
141 EVP_MD_CTX_init(&ctx);
142 EVP_DigestInit_ex(&ctx, Hash, NULL);
143 EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);
144 EVP_DigestUpdate(&ctx, mHash, hLen);
145 if (maskedDBLen - i)
146 EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i);
147 EVP_DigestFinal(&ctx, H_, NULL);
148 EVP_MD_CTX_cleanup(&ctx);
149 if (memcmp(H_, H, hLen))
150 {
151 RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_BAD_SIGNATURE);
152 ret = 0;
153 }
154 else
155 ret = 1;
156
157 err:
158 if (DB)
159 OPENSSL_free(DB);
160
161 return ret;
162
163 }
164
RSA_padding_add_PKCS1_PSS(RSA * rsa,unsigned char * EM,const unsigned char * mHash,const EVP_MD * Hash,int sLen)165 int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,
166 const unsigned char *mHash,
167 const EVP_MD *Hash, int sLen)
168 {
169 int i;
170 int ret = 0;
171 int hLen, maskedDBLen, MSBits, emLen;
172 unsigned char *H, *salt = NULL, *p;
173 EVP_MD_CTX ctx;
174
175 hLen = EVP_MD_size(Hash);
176 /*
177 * Negative sLen has special meanings:
178 * -1 sLen == hLen
179 * -2 salt length is maximized
180 * -N reserved
181 */
182 if (sLen == -1) sLen = hLen;
183 else if (sLen == -2) sLen = -2;
184 else if (sLen < -2)
185 {
186 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);
187 goto err;
188 }
189
190 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
191 emLen = RSA_size(rsa);
192 if (MSBits == 0)
193 {
194 *EM++ = 0;
195 emLen--;
196 }
197 if (sLen == -2)
198 {
199 sLen = emLen - hLen - 2;
200 }
201 else if (emLen < (hLen + sLen + 2))
202 {
203 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
204 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
205 goto err;
206 }
207 if (sLen > 0)
208 {
209 salt = OPENSSL_malloc(sLen);
210 if (!salt)
211 {
212 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,
213 ERR_R_MALLOC_FAILURE);
214 goto err;
215 }
216 if (!RAND_bytes(salt, sLen))
217 goto err;
218 }
219 maskedDBLen = emLen - hLen - 1;
220 H = EM + maskedDBLen;
221 EVP_MD_CTX_init(&ctx);
222 EVP_DigestInit_ex(&ctx, Hash, NULL);
223 EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);
224 EVP_DigestUpdate(&ctx, mHash, hLen);
225 if (sLen)
226 EVP_DigestUpdate(&ctx, salt, sLen);
227 EVP_DigestFinal(&ctx, H, NULL);
228 EVP_MD_CTX_cleanup(&ctx);
229
230 /* Generate dbMask in place then perform XOR on it */
231 PKCS1_MGF1(EM, maskedDBLen, H, hLen, Hash);
232
233 p = EM;
234
235 /* Initial PS XORs with all zeroes which is a NOP so just update
236 * pointer. Note from a test above this value is guaranteed to
237 * be non-negative.
238 */
239 p += emLen - sLen - hLen - 2;
240 *p++ ^= 0x1;
241 if (sLen > 0)
242 {
243 for (i = 0; i < sLen; i++)
244 *p++ ^= salt[i];
245 }
246 if (MSBits)
247 EM[0] &= 0xFF >> (8 - MSBits);
248
249 /* H is already in place so just set final 0xbc */
250
251 EM[emLen - 1] = 0xbc;
252
253 ret = 1;
254
255 err:
256 if (salt)
257 OPENSSL_free(salt);
258
259 return ret;
260
261 }
262