1 /* $OpenBSD: rsa_pss.c,v 1.15 2022/01/07 09:55:32 tb Exp $ */
2 /* Written by Dr Stephen N Henson (steve@openssl.org) 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 <stdlib.h>
61 #include <string.h>
62
63 #include <openssl/bn.h>
64 #include <openssl/err.h>
65 #include <openssl/evp.h>
66 #include <openssl/rsa.h>
67 #include <openssl/sha.h>
68
69 #include "evp_locl.h"
70 #include "rsa_locl.h"
71
72 static const unsigned char zeroes[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
73
74 int
RSA_verify_PKCS1_PSS(RSA * rsa,const unsigned char * mHash,const EVP_MD * Hash,const unsigned char * EM,int sLen)75 RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash, const EVP_MD *Hash,
76 const unsigned char *EM, int sLen)
77 {
78 return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen);
79 }
80
81 int
RSA_verify_PKCS1_PSS_mgf1(RSA * rsa,const unsigned char * mHash,const EVP_MD * Hash,const EVP_MD * mgf1Hash,const unsigned char * EM,int sLen)82 RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash,
83 const EVP_MD *Hash, const EVP_MD *mgf1Hash, const unsigned char *EM,
84 int sLen)
85 {
86 int i;
87 int ret = 0;
88 int hLen, maskedDBLen, MSBits, emLen;
89 const unsigned char *H;
90 unsigned char *DB = NULL;
91 EVP_MD_CTX ctx;
92 unsigned char H_[EVP_MAX_MD_SIZE];
93
94 EVP_MD_CTX_init(&ctx);
95
96 if (mgf1Hash == NULL)
97 mgf1Hash = Hash;
98
99 hLen = EVP_MD_size(Hash);
100 if (hLen < 0)
101 goto err;
102 /*
103 * Negative sLen has special meanings:
104 * -1 sLen == hLen
105 * -2 salt length is autorecovered from signature
106 * -N reserved
107 */
108 if (sLen == -1)
109 sLen = hLen;
110 else if (sLen == -2)
111 sLen = -2;
112 else if (sLen < -2) {
113 RSAerror(RSA_R_SLEN_CHECK_FAILED);
114 goto err;
115 }
116
117 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
118 emLen = RSA_size(rsa);
119 if (EM[0] & (0xFF << MSBits)) {
120 RSAerror(RSA_R_FIRST_OCTET_INVALID);
121 goto err;
122 }
123 if (MSBits == 0) {
124 EM++;
125 emLen--;
126 }
127 if (emLen < (hLen + sLen + 2)) {
128 /* sLen can be small negative */
129 RSAerror(RSA_R_DATA_TOO_LARGE);
130 goto err;
131 }
132 if (EM[emLen - 1] != 0xbc) {
133 RSAerror(RSA_R_LAST_OCTET_INVALID);
134 goto err;
135 }
136 maskedDBLen = emLen - hLen - 1;
137 H = EM + maskedDBLen;
138 DB = malloc(maskedDBLen);
139 if (!DB) {
140 RSAerror(ERR_R_MALLOC_FAILURE);
141 goto err;
142 }
143 if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0)
144 goto err;
145 for (i = 0; i < maskedDBLen; i++)
146 DB[i] ^= EM[i];
147 if (MSBits)
148 DB[0] &= 0xFF >> (8 - MSBits);
149 for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++)
150 ;
151 if (DB[i++] != 0x1) {
152 RSAerror(RSA_R_SLEN_RECOVERY_FAILED);
153 goto err;
154 }
155 if (sLen >= 0 && (maskedDBLen - i) != sLen) {
156 RSAerror(RSA_R_SLEN_CHECK_FAILED);
157 goto err;
158 }
159 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
160 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) ||
161 !EVP_DigestUpdate(&ctx, mHash, hLen))
162 goto err;
163 if (maskedDBLen - i) {
164 if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i))
165 goto err;
166 }
167 if (!EVP_DigestFinal_ex(&ctx, H_, NULL))
168 goto err;
169 if (timingsafe_bcmp(H_, H, hLen)) {
170 RSAerror(RSA_R_BAD_SIGNATURE);
171 ret = 0;
172 } else
173 ret = 1;
174
175 err:
176 free(DB);
177 EVP_MD_CTX_cleanup(&ctx);
178
179 return ret;
180 }
181
182 int
RSA_padding_add_PKCS1_PSS(RSA * rsa,unsigned char * EM,const unsigned char * mHash,const EVP_MD * Hash,int sLen)183 RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,
184 const unsigned char *mHash, const EVP_MD *Hash, int sLen)
185 {
186 return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen);
187 }
188
189 int
RSA_padding_add_PKCS1_PSS_mgf1(RSA * rsa,unsigned char * EM,const unsigned char * mHash,const EVP_MD * Hash,const EVP_MD * mgf1Hash,int sLen)190 RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,
191 const unsigned char *mHash, const EVP_MD *Hash, const EVP_MD *mgf1Hash,
192 int sLen)
193 {
194 int i;
195 int ret = 0;
196 int hLen, maskedDBLen, MSBits, emLen;
197 unsigned char *H, *salt = NULL, *p;
198 EVP_MD_CTX ctx;
199
200 EVP_MD_CTX_init(&ctx);
201
202 if (mgf1Hash == NULL)
203 mgf1Hash = Hash;
204
205 hLen = EVP_MD_size(Hash);
206 if (hLen < 0)
207 goto err;
208 /*
209 * Negative sLen has special meanings:
210 * -1 sLen == hLen
211 * -2 salt length is maximized
212 * -N reserved
213 */
214 if (sLen == -1)
215 sLen = hLen;
216 else if (sLen == -2)
217 sLen = -2;
218 else if (sLen < -2) {
219 RSAerror(RSA_R_SLEN_CHECK_FAILED);
220 goto err;
221 }
222
223 MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
224 emLen = RSA_size(rsa);
225 if (MSBits == 0) {
226 *EM++ = 0;
227 emLen--;
228 }
229 if (sLen == -2)
230 sLen = emLen - hLen - 2;
231 else if (emLen < (hLen + sLen + 2)) {
232 RSAerror(RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
233 goto err;
234 }
235 if (sLen > 0) {
236 salt = malloc(sLen);
237 if (!salt) {
238 RSAerror(ERR_R_MALLOC_FAILURE);
239 goto err;
240 }
241 arc4random_buf(salt, sLen);
242 }
243 maskedDBLen = emLen - hLen - 1;
244 H = EM + maskedDBLen;
245 if (!EVP_DigestInit_ex(&ctx, Hash, NULL) ||
246 !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes) ||
247 !EVP_DigestUpdate(&ctx, mHash, hLen))
248 goto err;
249 if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen))
250 goto err;
251 if (!EVP_DigestFinal_ex(&ctx, H, NULL))
252 goto err;
253
254 /* Generate dbMask in place then perform XOR on it */
255 if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash))
256 goto err;
257
258 p = EM;
259
260 /*
261 * Initial PS XORs with all zeroes which is a NOP so just update
262 * pointer. Note from a test above this value is guaranteed to
263 * be non-negative.
264 */
265 p += emLen - sLen - hLen - 2;
266 *p++ ^= 0x1;
267 if (sLen > 0) {
268 for (i = 0; i < sLen; i++)
269 *p++ ^= salt[i];
270 }
271 if (MSBits)
272 EM[0] &= 0xFF >> (8 - MSBits);
273
274 /* H is already in place so just set final 0xbc */
275 EM[emLen - 1] = 0xbc;
276
277 ret = 1;
278
279 err:
280 free(salt);
281 EVP_MD_CTX_cleanup(&ctx);
282
283 return ret;
284 }
285