Annotation of src/usr.bin/ssh/ssh-ecdsa.c, Revision 1.20
1.20 ! djm 1: /* $OpenBSD: ssh-ecdsa.c,v 1.19 2022/10/28 00:37:24 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:
1.20 ! djm 103: static int
! 104: ssh_ecdsa_generate(struct sshkey *k, int bits)
! 105: {
! 106: EC_KEY *private;
! 107:
! 108: if ((k->ecdsa_nid = sshkey_ecdsa_bits_to_nid(bits)) == -1)
! 109: return SSH_ERR_KEY_LENGTH;
! 110: if ((private = EC_KEY_new_by_curve_name(k->ecdsa_nid)) == NULL)
! 111: return SSH_ERR_ALLOC_FAIL;
! 112: if (EC_KEY_generate_key(private) != 1) {
! 113: EC_KEY_free(private);
! 114: return SSH_ERR_LIBCRYPTO_ERROR;
! 115: }
! 116: EC_KEY_set_asn1_flag(private, OPENSSL_EC_NAMED_CURVE);
! 117: k->ecdsa = private;
! 118: return 0;
! 119: }
! 120:
1.11 djm 121: /* ARGSUSED */
1.1 djm 122: int
1.11 djm 123: ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
124: const u_char *data, size_t datalen, u_int compat)
1.1 djm 125: {
1.11 djm 126: ECDSA_SIG *sig = NULL;
1.15 djm 127: const BIGNUM *sig_r, *sig_s;
1.8 djm 128: int hash_alg;
129: u_char digest[SSH_DIGEST_MAX_LENGTH];
1.11 djm 130: size_t len, dlen;
131: struct sshbuf *b = NULL, *bb = NULL;
132: int ret = SSH_ERR_INTERNAL_ERROR;
1.1 djm 133:
1.11 djm 134: if (lenp != NULL)
135: *lenp = 0;
136: if (sigp != NULL)
137: *sigp = NULL;
138:
139: if (key == NULL || key->ecdsa == NULL ||
140: sshkey_type_plain(key->type) != KEY_ECDSA)
141: return SSH_ERR_INVALID_ARGUMENT;
142:
143: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
144: (dlen = ssh_digest_bytes(hash_alg)) == 0)
145: return SSH_ERR_INTERNAL_ERROR;
146: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
147: digest, sizeof(digest))) != 0)
148: goto out;
149:
150: if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) {
151: ret = SSH_ERR_LIBCRYPTO_ERROR;
152: goto out;
153: }
154:
155: if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {
156: ret = SSH_ERR_ALLOC_FAIL;
157: goto out;
158: }
1.15 djm 159: ECDSA_SIG_get0(sig, &sig_r, &sig_s);
160: if ((ret = sshbuf_put_bignum2(bb, sig_r)) != 0 ||
161: (ret = sshbuf_put_bignum2(bb, sig_s)) != 0)
1.11 djm 162: goto out;
163: if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 ||
164: (ret = sshbuf_put_stringb(b, bb)) != 0)
165: goto out;
166: len = sshbuf_len(b);
167: if (sigp != NULL) {
168: if ((*sigp = malloc(len)) == NULL) {
169: ret = SSH_ERR_ALLOC_FAIL;
170: goto out;
171: }
172: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 djm 173: }
174: if (lenp != NULL)
175: *lenp = len;
1.11 djm 176: ret = 0;
177: out:
178: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 179: sshbuf_free(b);
180: sshbuf_free(bb);
1.14 jsing 181: ECDSA_SIG_free(sig);
1.11 djm 182: return ret;
183: }
1.1 djm 184:
1.11 djm 185: /* ARGSUSED */
1.1 djm 186: int
1.11 djm 187: ssh_ecdsa_verify(const struct sshkey *key,
188: const u_char *signature, size_t signaturelen,
189: const u_char *data, size_t datalen, u_int compat)
1.1 djm 190: {
1.11 djm 191: ECDSA_SIG *sig = NULL;
1.15 djm 192: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.8 djm 193: int hash_alg;
1.11 djm 194: u_char digest[SSH_DIGEST_MAX_LENGTH];
195: size_t dlen;
196: int ret = SSH_ERR_INTERNAL_ERROR;
197: struct sshbuf *b = NULL, *sigbuf = NULL;
198: char *ktype = NULL;
199:
200: if (key == NULL || key->ecdsa == NULL ||
1.13 djm 201: sshkey_type_plain(key->type) != KEY_ECDSA ||
202: signature == NULL || signaturelen == 0)
1.11 djm 203: return SSH_ERR_INVALID_ARGUMENT;
204:
205: if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||
206: (dlen = ssh_digest_bytes(hash_alg)) == 0)
207: return SSH_ERR_INTERNAL_ERROR;
1.7 djm 208:
1.1 djm 209: /* fetch signature */
1.11 djm 210: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
211: return SSH_ERR_ALLOC_FAIL;
212: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
213: sshbuf_froms(b, &sigbuf) != 0) {
214: ret = SSH_ERR_INVALID_FORMAT;
215: goto out;
216: }
217: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
218: ret = SSH_ERR_KEY_TYPE_MISMATCH;
219: goto out;
220: }
221: if (sshbuf_len(b) != 0) {
222: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
223: goto out;
1.1 djm 224: }
225:
226: /* parse signature */
1.16 djm 227: if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
228: sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
229: ret = SSH_ERR_INVALID_FORMAT;
1.11 djm 230: goto out;
231: }
1.16 djm 232: if ((sig = ECDSA_SIG_new()) == NULL) {
233: ret = SSH_ERR_ALLOC_FAIL;
1.11 djm 234: goto out;
235: }
1.15 djm 236: if (!ECDSA_SIG_set0(sig, sig_r, sig_s)) {
237: ret = SSH_ERR_LIBCRYPTO_ERROR;
238: goto out;
239: }
240: sig_r = sig_s = NULL; /* transferred */
241:
1.11 djm 242: if (sshbuf_len(sigbuf) != 0) {
243: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
244: goto out;
245: }
246: if ((ret = ssh_digest_memory(hash_alg, data, datalen,
247: digest, sizeof(digest))) != 0)
248: goto out;
249:
250: switch (ECDSA_do_verify(digest, dlen, sig, key->ecdsa)) {
251: case 1:
252: ret = 0;
253: break;
254: case 0:
255: ret = SSH_ERR_SIGNATURE_INVALID;
256: goto out;
257: default:
258: ret = SSH_ERR_LIBCRYPTO_ERROR;
259: goto out;
1.8 djm 260: }
1.1 djm 261:
1.11 djm 262: out:
1.9 djm 263: explicit_bzero(digest, sizeof(digest));
1.12 mmcc 264: sshbuf_free(sigbuf);
265: sshbuf_free(b);
1.14 jsing 266: ECDSA_SIG_free(sig);
1.15 djm 267: BN_clear_free(sig_r);
268: BN_clear_free(sig_s);
1.11 djm 269: free(ktype);
1.1 djm 270: return ret;
271: }
1.17 djm 272:
1.18 djm 273: /* NB. not static; used by ECDSA-SK */
274: const struct sshkey_impl_funcs sshkey_ecdsa_funcs = {
1.17 djm 275: /* .size = */ ssh_ecdsa_size,
276: /* .alloc = */ NULL,
277: /* .cleanup = */ ssh_ecdsa_cleanup,
1.18 djm 278: /* .equal = */ ssh_ecdsa_equal,
1.19 djm 279: /* .ssh_serialize_public = */ ssh_ecdsa_serialize_public,
1.20 ! djm 280: /* .generate = */ ssh_ecdsa_generate,
1.17 djm 281: };
282:
283: const struct sshkey_impl sshkey_ecdsa_nistp256_impl = {
284: /* .name = */ "ecdsa-sha2-nistp256",
285: /* .shortname = */ "ECDSA",
286: /* .sigalg = */ NULL,
287: /* .type = */ KEY_ECDSA,
288: /* .nid = */ NID_X9_62_prime256v1,
289: /* .cert = */ 0,
290: /* .sigonly = */ 0,
291: /* .keybits = */ 0,
292: /* .funcs = */ &sshkey_ecdsa_funcs,
293: };
294:
295: const struct sshkey_impl sshkey_ecdsa_nistp256_cert_impl = {
296: /* .name = */ "ecdsa-sha2-nistp256-cert-v01@openssh.com",
297: /* .shortname = */ "ECDSA-CERT",
298: /* .sigalg = */ NULL,
299: /* .type = */ KEY_ECDSA_CERT,
300: /* .nid = */ NID_X9_62_prime256v1,
301: /* .cert = */ 1,
302: /* .sigonly = */ 0,
303: /* .keybits = */ 0,
304: /* .funcs = */ &sshkey_ecdsa_funcs,
305: };
306:
307: const struct sshkey_impl sshkey_ecdsa_nistp384_impl = {
308: /* .name = */ "ecdsa-sha2-nistp384",
309: /* .shortname = */ "ECDSA",
310: /* .sigalg = */ NULL,
311: /* .type = */ KEY_ECDSA,
312: /* .nid = */ NID_secp384r1,
313: /* .cert = */ 0,
314: /* .sigonly = */ 0,
315: /* .keybits = */ 0,
316: /* .funcs = */ &sshkey_ecdsa_funcs,
317: };
318:
319: const struct sshkey_impl sshkey_ecdsa_nistp384_cert_impl = {
320: /* .name = */ "ecdsa-sha2-nistp384-cert-v01@openssh.com",
321: /* .shortname = */ "ECDSA-CERT",
322: /* .sigalg = */ NULL,
323: /* .type = */ KEY_ECDSA_CERT,
324: /* .nid = */ NID_secp384r1,
325: /* .cert = */ 1,
326: /* .sigonly = */ 0,
327: /* .keybits = */ 0,
328: /* .funcs = */ &sshkey_ecdsa_funcs,
329: };
330:
331: const struct sshkey_impl sshkey_ecdsa_nistp521_impl = {
332: /* .name = */ "ecdsa-sha2-nistp521",
333: /* .shortname = */ "ECDSA",
334: /* .sigalg = */ NULL,
335: /* .type = */ KEY_ECDSA,
336: /* .nid = */ NID_secp521r1,
337: /* .cert = */ 0,
338: /* .sigonly = */ 0,
339: /* .keybits = */ 0,
340: /* .funcs = */ &sshkey_ecdsa_funcs,
341: };
342:
343: const struct sshkey_impl sshkey_ecdsa_nistp521_cert_impl = {
344: /* .name = */ "ecdsa-sha2-nistp521-cert-v01@openssh.com",
345: /* .shortname = */ "ECDSA-CERT",
346: /* .sigalg = */ NULL,
347: /* .type = */ KEY_ECDSA_CERT,
348: /* .nid = */ NID_secp521r1,
349: /* .cert = */ 1,
350: /* .sigonly = */ 0,
351: /* .keybits = */ 0,
352: /* .funcs = */ &sshkey_ecdsa_funcs,
353: };
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