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, write to the Free Software Foundation, Inc., 51
17 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
23 #include "decodekey.h"
25 #include "keystructs.h"
31 #include <nettle/md5.h>
32 #include <nettle/ripemd160.h>
33 #include <nettle/sha.h>
40 int check_packet_sighash(struct openpgp_publickey *key,
41 struct openpgp_packet *packet,
42 struct openpgp_packet *sig)
46 size_t siglen, unhashedlen;
47 struct sha1_ctx sha1_context;
48 struct sha1x_ctx sha1x_context;
49 struct md5_ctx md5_context;
50 #ifdef NETTLE_WITH_RIPEMD160
51 struct ripemd160_ctx ripemd160_context;
53 #ifdef NETTLE_WITH_SHA224
54 struct sha224_ctx sha224_context;
56 #ifdef NETTLE_WITH_SHA256
57 struct sha256_ctx sha256_context;
59 #ifdef NETTLE_WITH_SHA384
60 struct sha384_ctx sha384_context;
62 #ifdef NETTLE_WITH_SHA512
63 struct sha512_ctx sha512_context;
66 uint8_t packetheader[5];
76 keyheader[1] = key->publickey->length >> 8;
77 keyheader[2] = key->publickey->length & 0xFF;
78 hashdata[0] = keyheader;
80 hashdata[1] = key->publickey->data;
81 hashlen[1] = key->publickey->length;
84 switch (sig->data[0]) {
87 hashtype = sig->data[16];
90 if (packet->tag == OPENPGP_PACKET_PUBLICSUBKEY) {
91 packetheader[0] = 0x99;
92 packetheader[1] = packet->length >> 8;
93 packetheader[2] = packet->length & 0xFF;
94 hashdata[chunks] = packetheader;
99 // TODO: Things other than UIDS/subkeys?
100 hashdata[chunks] = packet->data;
101 hashlen[chunks] = packet->length;
105 hashdata[chunks] = &sig->data[2];
108 sighash = &sig->data[17];
111 hashtype = sig->data[3];
113 /* Check to see if this is an X509 based signature */
114 if (sig->data[2] == 0 || sig->data[2] == 100) {
118 res = parse_subpackets(&sig->data[4],
119 sig->length - 4, &len,
121 if (res != ONAK_E_OK) {
122 /* If it parses badly, reject it */
126 /* No unhashed data */
127 sig->data[4 + len] == 0 &&
128 sig->data[5 + len] == 0 &&
129 /* Dummy 0 checksum */
130 sig->data[6 + len] == 0 &&
131 sig->data[7 + len] == 0 &&
133 sig->data[8 + len] == 0 &&
134 sig->data[9 + len] == 1 &&
135 sig->data[10 + len] == 1) {
136 get_keyid(key, &keyid);
137 logthing(LOGTHING_DEBUG,
138 "Skipping X509 signature on 0x%016"
145 if (packet != NULL) {
146 if (packet->tag == OPENPGP_PACKET_PUBLICSUBKEY) {
147 packetheader[0] = 0x99;
148 packetheader[1] = packet->length >> 8;
149 packetheader[2] = packet->length & 0xFF;
150 hashdata[chunks] = packetheader;
153 } else if (packet->tag == OPENPGP_PACKET_UID ||
154 packet->tag == OPENPGP_PACKET_UAT) {
155 packetheader[0] = (packet->tag ==
156 OPENPGP_PACKET_UID) ? 0xB4 : 0xD1;
157 packetheader[1] = packet->length >> 24;
158 packetheader[2] = (packet->length >> 16) & 0xFF;
159 packetheader[3] = (packet->length >> 8) & 0xFF;
160 packetheader[4] = packet->length & 0xFF;
161 hashdata[chunks] = packetheader;
165 hashdata[chunks] = packet->data;
166 hashlen[chunks] = packet->length;
170 hashdata[chunks] = sig->data;
171 hashlen[chunks] = siglen = (sig->data[4] << 8) +
173 if (siglen > sig->length) {
174 /* Signature data exceed packet length, bogus */
181 v4trailer[2] = siglen >> 24;
182 v4trailer[3] = (siglen >> 16) & 0xFF;
183 v4trailer[4] = (siglen >> 8) & 0xFF;
184 v4trailer[5] = siglen & 0xFF;
185 hashdata[chunks] = v4trailer;
189 unhashedlen = (sig->data[siglen] << 8) +
190 sig->data[siglen + 1];
191 sighash = &sig->data[siglen + unhashedlen + 2];
194 get_keyid(key, &keyid);
195 logthing(LOGTHING_ERROR,
196 "Unknown signature version %d on 0x%016" PRIX64,
197 sig->data[0], keyid);
202 case OPENPGP_HASH_MD5:
203 md5_init(&md5_context);
204 for (i = 0; i < chunks; i++) {
205 md5_update(&md5_context, hashlen[i], hashdata[i]);
207 md5_digest(&md5_context, 16, hash);
209 case OPENPGP_HASH_SHA1:
210 sha1_init(&sha1_context);
211 for (i = 0; i < chunks; i++) {
212 sha1_update(&sha1_context, hashlen[i], hashdata[i]);
214 sha1_digest(&sha1_context, 20, hash);
216 case OPENPGP_HASH_RIPEMD160:
217 #ifdef NETTLE_WITH_RIPEMD160
218 ripemd160_init(&ripemd160_context);
219 for (i = 0; i < chunks; i++) {
220 ripemd160_update(&ripemd160_context, hashlen[i],
223 ripemd160_digest(&ripemd160_context, RIPEMD160_DIGEST_SIZE,
227 logthing(LOGTHING_INFO, "RIPEMD160 support not available.");
230 case OPENPGP_HASH_SHA1X:
231 sha1x_init(&sha1x_context);
232 for (i = 0; i < chunks; i++) {
233 sha1x_update(&sha1x_context, hashlen[i], hashdata[i]);
235 sha1x_digest(&sha1x_context, 20, hash);
237 case OPENPGP_HASH_SHA224:
238 #ifdef NETTLE_WITH_SHA224
239 sha224_init(&sha224_context);
240 for (i = 0; i < chunks; i++) {
241 sha224_update(&sha224_context, hashlen[i],
244 sha224_digest(&sha224_context, SHA224_DIGEST_SIZE, hash);
247 logthing(LOGTHING_INFO, "SHA224 support not available.");
250 case OPENPGP_HASH_SHA256:
251 #ifdef NETTLE_WITH_SHA256
252 sha256_init(&sha256_context);
253 for (i = 0; i < chunks; i++) {
254 sha256_update(&sha256_context, hashlen[i],
257 sha256_digest(&sha256_context, SHA256_DIGEST_SIZE, hash);
260 logthing(LOGTHING_INFO, "SHA256 support not available.");
263 case OPENPGP_HASH_SHA384:
264 #ifdef NETTLE_WITH_SHA384
265 sha384_init(&sha384_context);
266 for (i = 0; i < chunks; i++) {
267 sha384_update(&sha384_context, hashlen[i],
270 sha384_digest(&sha384_context, SHA384_DIGEST_SIZE, hash);
273 logthing(LOGTHING_INFO, "SHA384 support not available.");
276 case OPENPGP_HASH_SHA512:
277 #ifdef NETTLE_WITH_SHA512
278 sha512_init(&sha512_context);
279 for (i = 0; i < chunks; i++) {
280 sha512_update(&sha512_context, hashlen[i],
283 sha512_digest(&sha512_context, SHA512_DIGEST_SIZE, hash);
286 logthing(LOGTHING_INFO, "SHA512 support not available.");
290 get_keyid(key, &keyid);
291 logthing(LOGTHING_ERROR,
292 "Unsupported signature hash type %d on 0x%016" PRIX64,
298 logthing(LOGTHING_DEBUG, "Hash type: %d, %d chunks, "
299 "calculated: %02X%02X / actual: %02X%02X",
301 hash[0], hash[1], sighash[0], sighash[1]);
303 return (hash[0] == sighash[0] && hash[1] == sighash[1]);