Annotation of src/usr.bin/ssh/ssh-ecdsa.c, Revision 1.19
1.19 ! djm 1: /* $OpenBSD: ssh-ecdsa.c,v 1.18 2022/10/28 00:36:31 djm Exp $ */
1.1 djm 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: * Copyright (c) 2010 Damien Miller. All rights reserved.
5: *
6: * Redistribution and use in source and binary forms, with or without
7: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
27: #include <sys/types.h>
28:
29: #include <openssl/bn.h>
30: #include <openssl/ec.h>
31: #include <openssl/ecdsa.h>
32: #include <openssl/evp.h>
33:
34: #include <string.h>
35:
1.11 djm 36: #include "sshbuf.h"
37: #include "ssherr.h"
1.8 djm 38: #include "digest.h"
1.11 djm 39: #define SSHKEY_INTERNAL
40: #include "sshkey.h"
1.1 djm 41:
1.17 djm 42: static u_int
43: ssh_ecdsa_size(const struct sshkey *key)
44: {
45: switch (key->ecdsa_nid) {
46: case NID_X9_62_prime256v1:
47: return 256;
48: case NID_secp384r1:
49: return 384;
50: case NID_secp521r1:
51: return 521;
52: default:
53: return 0;
54: }
55: }
56:
57: static void
58: ssh_ecdsa_cleanup(struct sshkey *k)
59: {
60: EC_KEY_free(k->ecdsa);
61: k->ecdsa = NULL;
62: }
63:
1.18 djm 64: static int
65: ssh_ecdsa_equal(const struct sshkey *a, const struct sshkey *b)
66: {
67: const EC_GROUP *grp_a, *grp_b;
68: const EC_POINT *pub_a, *pub_b;
69:
70: if (a->ecdsa == NULL || b->ecdsa == NULL)
71: return 0;
72: if ((grp_a = EC_KEY_get0_group(a->ecdsa)) == NULL ||
73: (grp_b = EC_KEY_get0_group(b->ecdsa)) == NULL)
74: return 0;
75: if ((pub_a = EC_KEY_get0_public_key(a->ecdsa)) == NULL ||
76: (pub_b = EC_KEY_get0_public_key(b->ecdsa)) == NULL)
77: return 0;
78: if (EC_GROUP_cmp(grp_a, grp_b, NULL) != 0)
79: return 0;
80: if (EC_POINT_cmp(grp_a, pub_a, pub_b, NULL) != 0)
81: return 0;
1.19 ! djm 82:
1.18 djm 83: return 1;
84: }
85:
1.19 ! djm 86: static int
! 87: ssh_ecdsa_serialize_public(const struct sshkey *key, struct sshbuf *b,
! 88: const char *typename, enum sshkey_serialize_rep opts)
! 89: {
! 90: int r;
! 91:
! 92: if (key->ecdsa == NULL)
! 93: return SSH_ERR_INVALID_ARGUMENT;
! 94: if ((r = sshbuf_put_cstring(b, typename)) != 0 ||
! 95: (r = sshbuf_put_cstring(b,
! 96: sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
! 97: (r = sshbuf_put_eckey(b, key->ecdsa)) != 0)
! 98: return r;
! 99:
! 100: return 0;
! 101: }
! 102:
1.11 djm 103: /* ARGSUSED */
1.1 djm 104: int
1.11 djm 105: ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
106: const u_char *data, size_t datalen, u_int compat)
1.1 djm 107: {
1.11 djm 108: ECDSA_SIG *sig = NULL;
1.15 djm 109: const BIGNUM *sig_r, *sig_s;
1.8 djm 110: int hash_alg;
111: u_char digest[SSH_DIGEST_MAX_LENGTH];
1.11 djm 112: size_t len, dlen;
113: struct sshbuf *b = NULL, *bb = NULL;
114: int ret = SSH_ERR_INTERNAL_ERROR;
1.1 djm 115:
1.11 djm 116: if (lenp != NULL)
117: *lenp = 0;
118: if (sigp != NULL)
119: *sigp = NULL;
120:
121: if (key == NULL || key->ecdsa == NULL ||
122: sshkey_type_plain(key->type) != KEY_ECDSA)
123: return SSH_ERR_INVALID_ARGUMENT;
124:
125: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
126: (dlen = ssh_digest_bytes(hash_alg)) == 0)
127: return SSH_ERR_INTERNAL_ERROR;
128: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
129: digest, sizeof(digest))) != 0)
130: goto out;
131:
132: if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) {
133: ret = SSH_ERR_LIBCRYPTO_ERROR;
134: goto out;
135: }
136:
137: if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
138: ret = SSH_ERR_ALLOC_FAIL;
139: goto out;
140: }
1.15 djm 141: ECDSA_SIG_get0(sig, &sig_r, &sig_s);
142: if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
143: (ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
1.11 djm 144: goto out;
145: if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
146: (ret = sshbuf_put_stringb(b, bb)) != 0)
147: goto out;
148: len = sshbuf_len(b);
149: if (sigp != NULL) {
150: if ((*sigp = malloc(len)) == NULL) {
151: ret = SSH_ERR_ALLOC_FAIL;
152: goto out;
153: }
154: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 djm 155: }
156: if (lenp != NULL)
157: *lenp = len;
1.11 djm 158: ret = 0;
159: out:
160: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 161: sshbuf_free(b);
162: sshbuf_free(bb);
1.14 jsing 163: ECDSA_SIG_free(sig);
1.11 djm 164: return ret;
165: }
1.1 djm 166:
1.11 djm 167: /* ARGSUSED */
1.1 djm 168: int
1.11 djm 169: ssh_ecdsa_verify(const struct sshkey *key,
170: const u_char *signature, size_t signaturelen,
171: const u_char *data, size_t datalen, u_int compat)
1.1 djm 172: {
1.11 djm 173: ECDSA_SIG *sig = NULL;
1.15 djm 174: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.8 djm 175: int hash_alg;
1.11 djm 176: u_char digest[SSH_DIGEST_MAX_LENGTH];
177: size_t dlen;
178: int ret = SSH_ERR_INTERNAL_ERROR;
179: struct sshbuf *b = NULL, *sigbuf = NULL;
180: char *ktype = NULL;
181:
182: if (key == NULL || key->ecdsa == NULL ||
1.13 djm 183: sshkey_type_plain(key->type) != KEY_ECDSA ||
184: signature == NULL || signaturelen == 0)
1.11 djm 185: return SSH_ERR_INVALID_ARGUMENT;
186:
187: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
188: (dlen = ssh_digest_bytes(hash_alg)) == 0)
189: return SSH_ERR_INTERNAL_ERROR;
1.7 djm 190:
1.1 djm 191: /* fetch signature */
1.11 djm 192: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
193: return SSH_ERR_ALLOC_FAIL;
194: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
195: sshbuf_froms(b, &sigbuf) != 0) {
196: ret = SSH_ERR_INVALID_FORMAT;
197: goto out;
198: }
199: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
200: ret = SSH_ERR_KEY_TYPE_MISMATCH;
201: goto out;
202: }
203: if (sshbuf_len(b) != 0) {
204: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
205: goto out;
1.1 djm 206: }
207:
208: /* parse signature */
1.16 djm 209: if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
210: sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
211: ret = SSH_ERR_INVALID_FORMAT;
1.11 djm 212: goto out;
213: }
1.16 djm 214: if ((sig = ECDSA_SIG_new()) == NULL) {
215: ret = SSH_ERR_ALLOC_FAIL;
1.11 djm 216: goto out;
217: }
1.15 djm 218: if (!ECDSA_SIG_set0(sig, sig_r, sig_s)) {
219: ret = SSH_ERR_LIBCRYPTO_ERROR;
220: goto out;
221: }
222: sig_r = sig_s = NULL; /* transferred */
223:
1.11 djm 224: if (sshbuf_len(sigbuf) != 0) {
225: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
226: goto out;
227: }
228: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
229: digest, sizeof(digest))) != 0)
230: goto out;
231:
232: switch (ECDSA_do_verify(digest, dlen, sig, key->ecdsa)) {
233: case 1:
234: ret = 0;
235: break;
236: case 0:
237: ret = SSH_ERR_SIGNATURE_INVALID;
238: goto out;
239: default:
240: ret = SSH_ERR_LIBCRYPTO_ERROR;
241: goto out;
1.8 djm 242: }
1.1 djm 243:
1.11 djm 244: out:
1.9 djm 245: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 246: sshbuf_free(sigbuf);
247: sshbuf_free(b);
1.14 jsing 248: ECDSA_SIG_free(sig);
1.15 djm 249: BN_clear_free(sig_r);
250: BN_clear_free(sig_s);
1.11 djm 251: free(ktype);
1.1 djm 252: return ret;
253: }
1.17 djm 254:
1.18 djm 255: /* NB. not static; used by ECDSA-SK */
256: const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
1.17 djm 257: /* .size = */ ssh_ecdsa_size,
258: /* .alloc = */ NULL,
259: /* .cleanup = */ ssh_ecdsa_cleanup,
1.18 djm 260: /* .equal = */ ssh_ecdsa_equal,
1.19 ! djm 261: /* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
1.17 djm 262: };
263:
264: const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
265: /* .name = */ "ecdsa-sha2-nistp256",
266: /* .shortname = */ "ECDSA",
267: /* .sigalg = */ NULL,
268: /* .type = */ KEY_ECDSA,
269: /* .nid = */ NID_X9_62_prime256v1,
270: /* .cert = */ 0,
271: /* .sigonly = */ 0,
272: /* .keybits = */ 0,
273: /* .funcs = */ &sshkey_ecdsa_funcs,
274: };
275:
276: const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
277: /* .name = */ "ecdsa-sha2-nistp256-cert-v01@openssh.com",
278: /* .shortname = */ "ECDSA-CERT",
279: /* .sigalg = */ NULL,
280: /* .type = */ KEY_ECDSA_CERT,
281: /* .nid = */ NID_X9_62_prime256v1,
282: /* .cert = */ 1,
283: /* .sigonly = */ 0,
284: /* .keybits = */ 0,
285: /* .funcs = */ &sshkey_ecdsa_funcs,
286: };
287:
288: const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
289: /* .name = */ "ecdsa-sha2-nistp384",
290: /* .shortname = */ "ECDSA",
291: /* .sigalg = */ NULL,
292: /* .type = */ KEY_ECDSA,
293: /* .nid = */ NID_secp384r1,
294: /* .cert = */ 0,
295: /* .sigonly = */ 0,
296: /* .keybits = */ 0,
297: /* .funcs = */ &sshkey_ecdsa_funcs,
298: };
299:
300: const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
301: /* .name = */ "ecdsa-sha2-nistp384-cert-v01@openssh.com",
302: /* .shortname = */ "ECDSA-CERT",
303: /* .sigalg = */ NULL,
304: /* .type = */ KEY_ECDSA_CERT,
305: /* .nid = */ NID_secp384r1,
306: /* .cert = */ 1,
307: /* .sigonly = */ 0,
308: /* .keybits = */ 0,
309: /* .funcs = */ &sshkey_ecdsa_funcs,
310: };
311:
312: const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
313: /* .name = */ "ecdsa-sha2-nistp521",
314: /* .shortname = */ "ECDSA",
315: /* .sigalg = */ NULL,
316: /* .type = */ KEY_ECDSA,
317: /* .nid = */ NID_secp521r1,
318: /* .cert = */ 0,
319: /* .sigonly = */ 0,
320: /* .keybits = */ 0,
321: /* .funcs = */ &sshkey_ecdsa_funcs,
322: };
323:
324: const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
325: /* .name = */ "ecdsa-sha2-nistp521-cert-v01@openssh.com",
326: /* .shortname = */ "ECDSA-CERT",
327: /* .sigalg = */ NULL,
328: /* .type = */ KEY_ECDSA_CERT,
329: /* .nid = */ NID_secp521r1,
330: /* .cert = */ 1,
331: /* .sigonly = */ 0,
332: /* .keybits = */ 0,
333: /* .funcs = */ &sshkey_ecdsa_funcs,
334: };
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