1 | /* |
2 | * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. |
3 | * |
4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at |
7 | * https://www.openssl.org/source/license.html |
8 | */ |
9 | |
10 | #include <stdio.h> |
11 | #include "internal/cryptlib.h" |
12 | #include <openssl/bn.h> |
13 | #include <openssl/rsa.h> |
14 | #include <openssl/objects.h> |
15 | #include <openssl/x509.h> |
16 | #include "crypto/x509.h" |
17 | #include "rsa_local.h" |
18 | |
19 | /* Size of an SSL signature: MD5+SHA1 */ |
20 | #define SSL_SIG_LENGTH 36 |
21 | |
22 | /* |
23 | * encode_pkcs1 encodes a DigestInfo prefix of hash |type| and digest |m|, as |
24 | * described in EMSA-PKCS1-v1_5-ENCODE, RFC 3447 section 9.2 step 2. This |
25 | * encodes the DigestInfo (T and tLen) but does not add the padding. |
26 | * |
27 | * On success, it returns one and sets |*out| to a newly allocated buffer |
28 | * containing the result and |*out_len| to its length. The caller must free |
29 | * |*out| with |OPENSSL_free|. Otherwise, it returns zero. |
30 | */ |
31 | static int encode_pkcs1(unsigned char **out, int *out_len, int type, |
32 | const unsigned char *m, unsigned int m_len) |
33 | { |
34 | X509_SIG sig; |
35 | X509_ALGOR algor; |
36 | ASN1_TYPE parameter; |
37 | ASN1_OCTET_STRING digest; |
38 | uint8_t *der = NULL; |
39 | int len; |
40 | |
41 | sig.algor = &algor; |
42 | sig.algor->algorithm = OBJ_nid2obj(type); |
43 | if (sig.algor->algorithm == NULL) { |
44 | RSAerr(RSA_F_ENCODE_PKCS1, RSA_R_UNKNOWN_ALGORITHM_TYPE); |
45 | return 0; |
46 | } |
47 | if (OBJ_length(sig.algor->algorithm) == 0) { |
48 | RSAerr(RSA_F_ENCODE_PKCS1, |
49 | RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD); |
50 | return 0; |
51 | } |
52 | parameter.type = V_ASN1_NULL; |
53 | parameter.value.ptr = NULL; |
54 | sig.algor->parameter = ¶meter; |
55 | |
56 | sig.digest = &digest; |
57 | sig.digest->data = (unsigned char *)m; |
58 | sig.digest->length = m_len; |
59 | |
60 | len = i2d_X509_SIG(&sig, &der); |
61 | if (len < 0) |
62 | return 0; |
63 | |
64 | *out = der; |
65 | *out_len = len; |
66 | return 1; |
67 | } |
68 | |
69 | int RSA_sign(int type, const unsigned char *m, unsigned int m_len, |
70 | unsigned char *sigret, unsigned int *siglen, RSA *rsa) |
71 | { |
72 | int encrypt_len, encoded_len = 0, ret = 0; |
73 | unsigned char *tmps = NULL; |
74 | const unsigned char *encoded = NULL; |
75 | |
76 | if (rsa->meth->rsa_sign) { |
77 | return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa); |
78 | } |
79 | |
80 | /* Compute the encoded digest. */ |
81 | if (type == NID_md5_sha1) { |
82 | /* |
83 | * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and |
84 | * earlier. It has no DigestInfo wrapper but otherwise is |
85 | * RSASSA-PKCS1-v1_5. |
86 | */ |
87 | if (m_len != SSL_SIG_LENGTH) { |
88 | RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH); |
89 | return 0; |
90 | } |
91 | encoded_len = SSL_SIG_LENGTH; |
92 | encoded = m; |
93 | } else { |
94 | if (!encode_pkcs1(&tmps, &encoded_len, type, m, m_len)) |
95 | goto err; |
96 | encoded = tmps; |
97 | } |
98 | |
99 | if (encoded_len > RSA_size(rsa) - RSA_PKCS1_PADDING_SIZE) { |
100 | RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY); |
101 | goto err; |
102 | } |
103 | encrypt_len = RSA_private_encrypt(encoded_len, encoded, sigret, rsa, |
104 | RSA_PKCS1_PADDING); |
105 | if (encrypt_len <= 0) |
106 | goto err; |
107 | |
108 | *siglen = encrypt_len; |
109 | ret = 1; |
110 | |
111 | err: |
112 | OPENSSL_clear_free(tmps, (size_t)encoded_len); |
113 | return ret; |
114 | } |
115 | |
116 | /* |
117 | * int_rsa_verify verifies an RSA signature in |sigbuf| using |rsa|. It may be |
118 | * called in two modes. If |rm| is NULL, it verifies the signature for digest |
119 | * |m|. Otherwise, it recovers the digest from the signature, writing the digest |
120 | * to |rm| and the length to |*prm_len|. |type| is the NID of the digest |
121 | * algorithm to use. It returns one on successful verification and zero |
122 | * otherwise. |
123 | */ |
124 | int int_rsa_verify(int type, const unsigned char *m, unsigned int m_len, |
125 | unsigned char *rm, size_t *prm_len, |
126 | const unsigned char *sigbuf, size_t siglen, RSA *rsa) |
127 | { |
128 | int decrypt_len, ret = 0, encoded_len = 0; |
129 | unsigned char *decrypt_buf = NULL, *encoded = NULL; |
130 | |
131 | if (siglen != (size_t)RSA_size(rsa)) { |
132 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH); |
133 | return 0; |
134 | } |
135 | |
136 | /* Recover the encoded digest. */ |
137 | decrypt_buf = OPENSSL_malloc(siglen); |
138 | if (decrypt_buf == NULL) { |
139 | RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE); |
140 | goto err; |
141 | } |
142 | |
143 | decrypt_len = RSA_public_decrypt((int)siglen, sigbuf, decrypt_buf, rsa, |
144 | RSA_PKCS1_PADDING); |
145 | if (decrypt_len <= 0) |
146 | goto err; |
147 | |
148 | if (type == NID_md5_sha1) { |
149 | /* |
150 | * NID_md5_sha1 corresponds to the MD5/SHA1 combination in TLS 1.1 and |
151 | * earlier. It has no DigestInfo wrapper but otherwise is |
152 | * RSASSA-PKCS1-v1_5. |
153 | */ |
154 | if (decrypt_len != SSL_SIG_LENGTH) { |
155 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); |
156 | goto err; |
157 | } |
158 | |
159 | if (rm != NULL) { |
160 | memcpy(rm, decrypt_buf, SSL_SIG_LENGTH); |
161 | *prm_len = SSL_SIG_LENGTH; |
162 | } else { |
163 | if (m_len != SSL_SIG_LENGTH) { |
164 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH); |
165 | goto err; |
166 | } |
167 | |
168 | if (memcmp(decrypt_buf, m, SSL_SIG_LENGTH) != 0) { |
169 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); |
170 | goto err; |
171 | } |
172 | } |
173 | } else if (type == NID_mdc2 && decrypt_len == 2 + 16 |
174 | && decrypt_buf[0] == 0x04 && decrypt_buf[1] == 0x10) { |
175 | /* |
176 | * Oddball MDC2 case: signature can be OCTET STRING. check for correct |
177 | * tag and length octets. |
178 | */ |
179 | if (rm != NULL) { |
180 | memcpy(rm, decrypt_buf + 2, 16); |
181 | *prm_len = 16; |
182 | } else { |
183 | if (m_len != 16) { |
184 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH); |
185 | goto err; |
186 | } |
187 | |
188 | if (memcmp(m, decrypt_buf + 2, 16) != 0) { |
189 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); |
190 | goto err; |
191 | } |
192 | } |
193 | } else { |
194 | /* |
195 | * If recovering the digest, extract a digest-sized output from the end |
196 | * of |decrypt_buf| for |encode_pkcs1|, then compare the decryption |
197 | * output as in a standard verification. |
198 | */ |
199 | if (rm != NULL) { |
200 | const EVP_MD *md = EVP_get_digestbynid(type); |
201 | if (md == NULL) { |
202 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_UNKNOWN_ALGORITHM_TYPE); |
203 | goto err; |
204 | } |
205 | |
206 | m_len = EVP_MD_size(md); |
207 | if (m_len > (size_t)decrypt_len) { |
208 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH); |
209 | goto err; |
210 | } |
211 | m = decrypt_buf + decrypt_len - m_len; |
212 | } |
213 | |
214 | /* Construct the encoded digest and ensure it matches. */ |
215 | if (!encode_pkcs1(&encoded, &encoded_len, type, m, m_len)) |
216 | goto err; |
217 | |
218 | if (encoded_len != decrypt_len |
219 | || memcmp(encoded, decrypt_buf, encoded_len) != 0) { |
220 | RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE); |
221 | goto err; |
222 | } |
223 | |
224 | /* Output the recovered digest. */ |
225 | if (rm != NULL) { |
226 | memcpy(rm, m, m_len); |
227 | *prm_len = m_len; |
228 | } |
229 | } |
230 | |
231 | ret = 1; |
232 | |
233 | err: |
234 | OPENSSL_clear_free(encoded, (size_t)encoded_len); |
235 | OPENSSL_clear_free(decrypt_buf, siglen); |
236 | return ret; |
237 | } |
238 | |
239 | int RSA_verify(int type, const unsigned char *m, unsigned int m_len, |
240 | const unsigned char *sigbuf, unsigned int siglen, RSA *rsa) |
241 | { |
242 | |
243 | if (rsa->meth->rsa_verify) { |
244 | return rsa->meth->rsa_verify(type, m, m_len, sigbuf, siglen, rsa); |
245 | } |
246 | |
247 | return int_rsa_verify(type, m, m_len, NULL, NULL, sigbuf, siglen, rsa); |
248 | } |
249 | |