2 * sigcheck.c - routines to check OpenPGP signatures
4 * Copyright 2012 Jonathan McDowell <noodles@earth.li>
6 * This program is free software: you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; version 2 of the License.
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program. If not, see <https://www.gnu.org/licenses/>.
21 #include "build-config.h"
22 #include "decodekey.h"
24 #include "keystructs.h"
30 #include <nettle/md5.h>
31 #include <nettle/ripemd160.h>
32 #include <nettle/sha.h>
39 int check_packet_sighash(struct openpgp_publickey *key,
40 struct openpgp_packet *packet,
41 struct openpgp_packet *sig)
45 size_t siglen, unhashedlen;
46 struct sha1_ctx sha1_context;
47 struct sha1x_ctx sha1x_context;
48 struct md5_ctx md5_context;
50 struct ripemd160_ctx ripemd160_context;
51 struct sha224_ctx sha224_context;
52 struct sha256_ctx sha256_context;
53 struct sha384_ctx sha384_context;
54 struct sha512_ctx sha512_context;
57 uint8_t packetheader[5];
67 keyheader[1] = key->publickey->length >> 8;
68 keyheader[2] = key->publickey->length & 0xFF;
69 hashdata[0] = keyheader;
71 hashdata[1] = key->publickey->data;
72 hashlen[1] = key->publickey->length;
75 switch (sig->data[0]) {
78 hashtype = sig->data[16];
81 if (packet->tag == OPENPGP_PACKET_PUBLICSUBKEY) {
82 packetheader[0] = 0x99;
83 packetheader[1] = packet->length >> 8;
84 packetheader[2] = packet->length & 0xFF;
85 hashdata[chunks] = packetheader;
90 // TODO: Things other than UIDS/subkeys?
91 hashdata[chunks] = packet->data;
92 hashlen[chunks] = packet->length;
96 hashdata[chunks] = &sig->data[2];
99 sighash = &sig->data[17];
102 hashtype = sig->data[3];
104 /* Check to see if this is an X509 based signature */
105 if (sig->data[2] == 0 || sig->data[2] == 100) {
109 res = parse_subpackets(&sig->data[4],
110 sig->length - 4, &len,
112 if (res != ONAK_E_OK) {
113 /* If it parses badly, reject it */
117 /* No unhashed data */
118 sig->data[4 + len] == 0 &&
119 sig->data[5 + len] == 0 &&
120 /* Dummy 0 checksum */
121 sig->data[6 + len] == 0 &&
122 sig->data[7 + len] == 0 &&
124 sig->data[8 + len] == 0 &&
125 sig->data[9 + len] == 1 &&
126 sig->data[10 + len] == 1) {
127 get_keyid(key, &keyid);
128 logthing(LOGTHING_DEBUG,
129 "Skipping X509 signature on 0x%016"
136 if (packet != NULL) {
137 if (packet->tag == OPENPGP_PACKET_PUBLICSUBKEY) {
138 packetheader[0] = 0x99;
139 packetheader[1] = packet->length >> 8;
140 packetheader[2] = packet->length & 0xFF;
141 hashdata[chunks] = packetheader;
144 } else if (packet->tag == OPENPGP_PACKET_UID ||
145 packet->tag == OPENPGP_PACKET_UAT) {
146 packetheader[0] = (packet->tag ==
147 OPENPGP_PACKET_UID) ? 0xB4 : 0xD1;
148 packetheader[1] = packet->length >> 24;
149 packetheader[2] = (packet->length >> 16) & 0xFF;
150 packetheader[3] = (packet->length >> 8) & 0xFF;
151 packetheader[4] = packet->length & 0xFF;
152 hashdata[chunks] = packetheader;
156 hashdata[chunks] = packet->data;
157 hashlen[chunks] = packet->length;
161 hashdata[chunks] = sig->data;
162 hashlen[chunks] = siglen = (sig->data[4] << 8) +
164 if (siglen > sig->length) {
165 /* Signature data exceed packet length, bogus */
172 v4trailer[2] = siglen >> 24;
173 v4trailer[3] = (siglen >> 16) & 0xFF;
174 v4trailer[4] = (siglen >> 8) & 0xFF;
175 v4trailer[5] = siglen & 0xFF;
176 hashdata[chunks] = v4trailer;
180 unhashedlen = (sig->data[siglen] << 8) +
181 sig->data[siglen + 1];
182 sighash = &sig->data[siglen + unhashedlen + 2];
185 get_keyid(key, &keyid);
186 logthing(LOGTHING_ERROR,
187 "Unknown signature version %d on 0x%016" PRIX64,
188 sig->data[0], keyid);
193 case OPENPGP_HASH_MD5:
194 md5_init(&md5_context);
195 for (i = 0; i < chunks; i++) {
196 md5_update(&md5_context, hashlen[i], hashdata[i]);
198 md5_digest(&md5_context, 16, hash);
200 case OPENPGP_HASH_SHA1:
201 sha1_init(&sha1_context);
202 for (i = 0; i < chunks; i++) {
203 sha1_update(&sha1_context, hashlen[i], hashdata[i]);
205 sha1_digest(&sha1_context, 20, hash);
207 case OPENPGP_HASH_SHA1X:
208 sha1x_init(&sha1x_context);
209 for (i = 0; i < chunks; i++) {
210 sha1x_update(&sha1x_context, hashlen[i], hashdata[i]);
212 sha1x_digest(&sha1x_context, 20, hash);
215 case OPENPGP_HASH_RIPEMD160:
216 ripemd160_init(&ripemd160_context);
217 for (i = 0; i < chunks; i++) {
218 ripemd160_update(&ripemd160_context, hashlen[i],
221 ripemd160_digest(&ripemd160_context, RIPEMD160_DIGEST_SIZE,
224 case OPENPGP_HASH_SHA224:
225 sha224_init(&sha224_context);
226 for (i = 0; i < chunks; i++) {
227 sha224_update(&sha224_context, hashlen[i],
230 sha224_digest(&sha224_context, SHA224_DIGEST_SIZE, hash);
232 case OPENPGP_HASH_SHA256:
233 sha256_init(&sha256_context);
234 for (i = 0; i < chunks; i++) {
235 sha256_update(&sha256_context, hashlen[i],
238 sha256_digest(&sha256_context, SHA256_DIGEST_SIZE, hash);
240 case OPENPGP_HASH_SHA384:
241 sha384_init(&sha384_context);
242 for (i = 0; i < chunks; i++) {
243 sha384_update(&sha384_context, hashlen[i],
246 sha384_digest(&sha384_context, SHA384_DIGEST_SIZE, hash);
248 case OPENPGP_HASH_SHA512:
249 sha512_init(&sha512_context);
250 for (i = 0; i < chunks; i++) {
251 sha512_update(&sha512_context, hashlen[i],
254 sha512_digest(&sha512_context, SHA512_DIGEST_SIZE, hash);
258 get_keyid(key, &keyid);
259 logthing(LOGTHING_ERROR,
260 "Unsupported signature hash type %d on 0x%016" PRIX64,
266 logthing(LOGTHING_DEBUG, "Hash type: %d, %d chunks, "
267 "calculated: %02X%02X / actual: %02X%02X",
269 hash[0], hash[1], sighash[0], sighash[1]);
271 return (hash[0] == sighash[0] && hash[1] == sighash[1]);