Annotation of src/usr.bin/ssh/ssh-ecdsa.c, Revision 1.25
1.25 ! djm 1: /* $OpenBSD: ssh-ecdsa.c,v 1.24 2022/10/28 00:44:17 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,
1.22 djm 88: enum sshkey_serialize_rep opts)
1.19 djm 89: {
90: int r;
91:
92: if (key->ecdsa == NULL)
93: return SSH_ERR_INVALID_ARGUMENT;
1.22 djm 94: if ((r = sshbuf_put_cstring(b,
1.19 djm 95: sshkey_curve_nid_to_name(key->ecdsa_nid))) != 0 ||
96: (r = sshbuf_put_eckey(b, key->ecdsa)) != 0)
97: return r;
98:
99: return 0;
100: }
101:
1.20 djm 102: static int
1.24 djm 103: ssh_ecdsa_serialize_private(const struct sshkey *key, struct sshbuf *b,
104: enum sshkey_serialize_rep opts)
105: {
106: int r;
107:
108: if (!sshkey_is_cert(key)) {
109: if ((r = ssh_ecdsa_serialize_public(key, b, opts)) != 0)
110: return r;
111: }
112: if ((r = sshbuf_put_bignum2(b,
113: EC_KEY_get0_private_key(key->ecdsa))) != 0)
114: return r;
115: return 0;
116: }
117:
118: static int
1.20 djm 119: ssh_ecdsa_generate(struct sshkey *k, int bits)
120: {
121: EC_KEY *private;
122:
123: if ((k->ecdsa_nid = sshkey_ecdsa_bits_to_nid(bits)) == -1)
124: return SSH_ERR_KEY_LENGTH;
125: if ((private = EC_KEY_new_by_curve_name(k->ecdsa_nid)) == NULL)
126: return SSH_ERR_ALLOC_FAIL;
127: if (EC_KEY_generate_key(private) != 1) {
128: EC_KEY_free(private);
129: return SSH_ERR_LIBCRYPTO_ERROR;
130: }
131: EC_KEY_set_asn1_flag(private, OPENSSL_EC_NAMED_CURVE);
132: k->ecdsa = private;
133: return 0;
134: }
135:
1.21 djm 136: static int
137: ssh_ecdsa_copy_public(const struct sshkey *from, struct sshkey *to)
138: {
139: to->ecdsa_nid = from->ecdsa_nid;
140: if ((to->ecdsa = EC_KEY_new_by_curve_name(from->ecdsa_nid)) == NULL)
141: return SSH_ERR_ALLOC_FAIL;
142: if (EC_KEY_set_public_key(to->ecdsa,
143: EC_KEY_get0_public_key(from->ecdsa)) != 1)
144: return SSH_ERR_LIBCRYPTO_ERROR; /* caller will free k->ecdsa */
145: return 0;
146: }
147:
1.22 djm 148: static int
149: ssh_ecdsa_deserialize_public(const char *ktype, struct sshbuf *b,
150: struct sshkey *key)
151: {
1.25 ! djm 152: int r;
1.22 djm 153: char *curve = NULL;
154:
1.25 ! djm 155: if ((key->ecdsa_nid = sshkey_ecdsa_nid_from_name(ktype)) == -1)
! 156: return SSH_ERR_INVALID_ARGUMENT;
! 157: if ((r = sshbuf_get_cstring(b, &curve, NULL)) != 0)
1.22 djm 158: goto out;
159: if (key->ecdsa_nid != sshkey_curve_name_to_nid(curve)) {
1.25 ! djm 160: r = SSH_ERR_EC_CURVE_MISMATCH;
1.22 djm 161: goto out;
162: }
163: EC_KEY_free(key->ecdsa);
1.25 ! djm 164: key->ecdsa = NULL;
1.22 djm 165: if ((key->ecdsa = EC_KEY_new_by_curve_name(key->ecdsa_nid)) == NULL) {
1.25 ! djm 166: r = SSH_ERR_LIBCRYPTO_ERROR;
1.22 djm 167: goto out;
168: }
1.25 ! djm 169: if ((r = sshbuf_get_eckey(b, key->ecdsa)) != 0)
! 170: goto out;
! 171: if (sshkey_ec_validate_public(EC_KEY_get0_group(key->ecdsa),
! 172: EC_KEY_get0_public_key(key->ecdsa)) != 0) {
! 173: r = SSH_ERR_KEY_INVALID_EC_VALUE;
1.22 djm 174: goto out;
175: }
1.25 ! djm 176: /* success */
! 177: r = 0;
! 178: #ifdef DEBUG_PK
! 179: sshkey_dump_ec_point(EC_KEY_get0_group(key->ecdsa),
! 180: EC_KEY_get0_public_key(key->ecdsa));
! 181: #endif
! 182: out:
! 183: free(curve);
! 184: if (r != 0) {
! 185: EC_KEY_free(key->ecdsa);
! 186: key->ecdsa = NULL;
! 187: }
! 188: return r;
! 189: }
! 190:
! 191: static int
! 192: ssh_ecdsa_deserialize_private(const char *ktype, struct sshbuf *b,
! 193: struct sshkey *key)
! 194: {
! 195: int r;
! 196: BIGNUM *exponent = NULL;
! 197:
! 198: if (!sshkey_is_cert(key)) {
! 199: if ((r = ssh_ecdsa_deserialize_public(ktype, b, key)) != 0)
! 200: return r;
! 201: }
! 202: if ((r = sshbuf_get_bignum2(b, &exponent)) != 0)
1.22 djm 203: goto out;
1.25 ! djm 204: if (EC_KEY_set_private_key(key->ecdsa, exponent) != 1) {
! 205: r = SSH_ERR_LIBCRYPTO_ERROR;
1.22 djm 206: goto out;
207: }
1.25 ! djm 208: if ((r = sshkey_ec_validate_private(key->ecdsa)) != 0)
1.22 djm 209: goto out;
210: /* success */
1.25 ! djm 211: r = 0;
1.22 djm 212: out:
1.25 ! djm 213: BN_clear_free(exponent);
! 214: return r;
1.22 djm 215: }
216:
1.11 djm 217: /* ARGSUSED */
1.23 djm 218: static int
219: ssh_ecdsa_sign(struct sshkey *key,
220: u_char **sigp, size_t *lenp,
221: const u_char *data, size_t dlen,
222: const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
1.1 djm 223: {
1.23 djm 224: ECDSA_SIG *esig = NULL;
1.15 djm 225: const BIGNUM *sig_r, *sig_s;
1.8 djm 226: int hash_alg;
227: u_char digest[SSH_DIGEST_MAX_LENGTH];
1.23 djm 228: size_t len, hlen;
1.11 djm 229: struct sshbuf *b = NULL, *bb = NULL;
230: int ret = SSH_ERR_INTERNAL_ERROR;
1.1 djm 231:
1.11 djm 232: if (lenp != NULL)
233: *lenp = 0;
234: if (sigp != NULL)
235: *sigp = NULL;
236:
237: if (key == NULL || key->ecdsa == NULL ||
238: sshkey_type_plain(key->type) != KEY_ECDSA)
239: return SSH_ERR_INVALID_ARGUMENT;
240:
241: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
1.23 djm 242: (hlen = ssh_digest_bytes(hash_alg)) == 0)
1.11 djm 243: return SSH_ERR_INTERNAL_ERROR;
1.23 djm 244: if ((ret = ssh_digest_memory(hash_alg, data, dlen,
1.11 djm 245: digest, sizeof(digest))) != 0)
246: goto out;
247:
1.23 djm 248: if ((esig = ECDSA_do_sign(digest, hlen, key->ecdsa)) == NULL) {
1.11 djm 249: ret = SSH_ERR_LIBCRYPTO_ERROR;
250: goto out;
251: }
252:
253: if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
254: ret = SSH_ERR_ALLOC_FAIL;
255: goto out;
256: }
1.23 djm 257: ECDSA_SIG_get0(esig, &sig_r, &sig_s);
1.15 djm 258: if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
259: (ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
1.11 djm 260: goto out;
261: if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
262: (ret = sshbuf_put_stringb(b, bb)) != 0)
263: goto out;
264: len = sshbuf_len(b);
265: if (sigp != NULL) {
266: if ((*sigp = malloc(len)) == NULL) {
267: ret = SSH_ERR_ALLOC_FAIL;
268: goto out;
269: }
270: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 djm 271: }
272: if (lenp != NULL)
273: *lenp = len;
1.11 djm 274: ret = 0;
275: out:
276: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 277: sshbuf_free(b);
278: sshbuf_free(bb);
1.23 djm 279: ECDSA_SIG_free(esig);
1.11 djm 280: return ret;
281: }
1.1 djm 282:
1.11 djm 283: /* ARGSUSED */
1.23 djm 284: static int
1.11 djm 285: ssh_ecdsa_verify(const struct sshkey *key,
1.23 djm 286: const u_char *sig, size_t siglen,
287: const u_char *data, size_t dlen, const char *alg, u_int compat,
288: struct sshkey_sig_details **detailsp)
1.1 djm 289: {
1.23 djm 290: ECDSA_SIG *esig = NULL;
1.15 djm 291: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.8 djm 292: int hash_alg;
1.11 djm 293: u_char digest[SSH_DIGEST_MAX_LENGTH];
1.23 djm 294: size_t hlen;
1.11 djm 295: int ret = SSH_ERR_INTERNAL_ERROR;
296: struct sshbuf *b = NULL, *sigbuf = NULL;
297: char *ktype = NULL;
298:
299: if (key == NULL || key->ecdsa == NULL ||
1.13 djm 300: sshkey_type_plain(key->type) != KEY_ECDSA ||
1.23 djm 301: sig == NULL || siglen == 0)
1.11 djm 302: return SSH_ERR_INVALID_ARGUMENT;
303:
304: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
1.23 djm 305: (hlen = ssh_digest_bytes(hash_alg)) == 0)
1.11 djm 306: return SSH_ERR_INTERNAL_ERROR;
1.7 djm 307:
1.1 djm 308: /* fetch signature */
1.23 djm 309: if ((b = sshbuf_from(sig, siglen)) == NULL)
1.11 djm 310: return SSH_ERR_ALLOC_FAIL;
311: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
312: sshbuf_froms(b, &sigbuf) != 0) {
313: ret = SSH_ERR_INVALID_FORMAT;
314: goto out;
315: }
316: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
317: ret = SSH_ERR_KEY_TYPE_MISMATCH;
318: goto out;
319: }
320: if (sshbuf_len(b) != 0) {
321: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
322: goto out;
1.1 djm 323: }
324:
325: /* parse signature */
1.16 djm 326: if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
327: sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
328: ret = SSH_ERR_INVALID_FORMAT;
1.11 djm 329: goto out;
330: }
1.23 djm 331: if ((esig = ECDSA_SIG_new()) == NULL) {
1.16 djm 332: ret = SSH_ERR_ALLOC_FAIL;
1.11 djm 333: goto out;
334: }
1.23 djm 335: if (!ECDSA_SIG_set0(esig, sig_r, sig_s)) {
1.15 djm 336: ret = SSH_ERR_LIBCRYPTO_ERROR;
337: goto out;
338: }
339: sig_r = sig_s = NULL; /* transferred */
340:
1.11 djm 341: if (sshbuf_len(sigbuf) != 0) {
342: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
343: goto out;
344: }
1.23 djm 345: if ((ret = ssh_digest_memory(hash_alg, data, dlen,
1.11 djm 346: digest, sizeof(digest))) != 0)
347: goto out;
348:
1.23 djm 349: switch (ECDSA_do_verify(digest, hlen, esig, key->ecdsa)) {
1.11 djm 350: case 1:
351: ret = 0;
352: break;
353: case 0:
354: ret = SSH_ERR_SIGNATURE_INVALID;
355: goto out;
356: default:
357: ret = SSH_ERR_LIBCRYPTO_ERROR;
358: goto out;
1.8 djm 359: }
1.1 djm 360:
1.11 djm 361: out:
1.9 djm 362: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 363: sshbuf_free(sigbuf);
364: sshbuf_free(b);
1.23 djm 365: ECDSA_SIG_free(esig);
1.15 djm 366: BN_clear_free(sig_r);
367: BN_clear_free(sig_s);
1.11 djm 368: free(ktype);
1.1 djm 369: return ret;
370: }
1.17 djm 371:
1.18 djm 372: /* NB. not static; used by ECDSA-SK */
373: const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
1.17 djm 374: /* .size = */ ssh_ecdsa_size,
375: /* .alloc = */ NULL,
376: /* .cleanup = */ ssh_ecdsa_cleanup,
1.18 djm 377: /* .equal = */ ssh_ecdsa_equal,
1.19 djm 378: /* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
1.22 djm 379: /* .ssh_deserialize_public = */ ssh_ecdsa_deserialize_public,
1.24 djm 380: /* .ssh_serialize_private = */ ssh_ecdsa_serialize_private,
1.25 ! djm 381: /* .ssh_deserialize_private = */ ssh_ecdsa_deserialize_private,
1.20 djm 382: /* .generate = */ ssh_ecdsa_generate,
1.21 djm 383: /* .copy_public = */ ssh_ecdsa_copy_public,
1.23 djm 384: /* .sign = */ ssh_ecdsa_sign,
385: /* .verify = */ ssh_ecdsa_verify,
1.17 djm 386: };
387:
388: const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
389: /* .name = */ "ecdsa-sha2-nistp256",
390: /* .shortname = */ "ECDSA",
391: /* .sigalg = */ NULL,
392: /* .type = */ KEY_ECDSA,
393: /* .nid = */ NID_X9_62_prime256v1,
394: /* .cert = */ 0,
395: /* .sigonly = */ 0,
396: /* .keybits = */ 0,
397: /* .funcs = */ &sshkey_ecdsa_funcs,
398: };
399:
400: const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
401: /* .name = */ "ecdsa-sha2-nistp256-cert-v01@openssh.com",
402: /* .shortname = */ "ECDSA-CERT",
403: /* .sigalg = */ NULL,
404: /* .type = */ KEY_ECDSA_CERT,
405: /* .nid = */ NID_X9_62_prime256v1,
406: /* .cert = */ 1,
407: /* .sigonly = */ 0,
408: /* .keybits = */ 0,
409: /* .funcs = */ &sshkey_ecdsa_funcs,
410: };
411:
412: const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
413: /* .name = */ "ecdsa-sha2-nistp384",
414: /* .shortname = */ "ECDSA",
415: /* .sigalg = */ NULL,
416: /* .type = */ KEY_ECDSA,
417: /* .nid = */ NID_secp384r1,
418: /* .cert = */ 0,
419: /* .sigonly = */ 0,
420: /* .keybits = */ 0,
421: /* .funcs = */ &sshkey_ecdsa_funcs,
422: };
423:
424: const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
425: /* .name = */ "ecdsa-sha2-nistp384-cert-v01@openssh.com",
426: /* .shortname = */ "ECDSA-CERT",
427: /* .sigalg = */ NULL,
428: /* .type = */ KEY_ECDSA_CERT,
429: /* .nid = */ NID_secp384r1,
430: /* .cert = */ 1,
431: /* .sigonly = */ 0,
432: /* .keybits = */ 0,
433: /* .funcs = */ &sshkey_ecdsa_funcs,
434: };
435:
436: const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
437: /* .name = */ "ecdsa-sha2-nistp521",
438: /* .shortname = */ "ECDSA",
439: /* .sigalg = */ NULL,
440: /* .type = */ KEY_ECDSA,
441: /* .nid = */ NID_secp521r1,
442: /* .cert = */ 0,
443: /* .sigonly = */ 0,
444: /* .keybits = */ 0,
445: /* .funcs = */ &sshkey_ecdsa_funcs,
446: };
447:
448: const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
449: /* .name = */ "ecdsa-sha2-nistp521-cert-v01@openssh.com",
450: /* .shortname = */ "ECDSA-CERT",
451: /* .sigalg = */ NULL,
452: /* .type = */ KEY_ECDSA_CERT,
453: /* .nid = */ NID_secp521r1,
454: /* .cert = */ 1,
455: /* .sigonly = */ 0,
456: /* .keybits = */ 0,
457: /* .funcs = */ &sshkey_ecdsa_funcs,
458: };
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