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