Annotation of src/usr.bin/ssh/ssh-ed25519-sk.c, Revision 1.8
1.8 ! djm 1: /* $OpenBSD: ssh-ed25519-sk.c,v 1.7 2022/10/28 00:35:40 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2019 Markus Friedl. All rights reserved.
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: */
1.4 djm 17:
18: /* #define DEBUG_SK 1 */
19:
1.1 markus 20: #define SSHKEY_INTERNAL
21: #include <sys/types.h>
22: #include <limits.h>
23:
24: #include "crypto_api.h"
25:
26: #include <string.h>
27: #include <stdarg.h>
28:
29: #include "log.h"
30: #include "sshbuf.h"
31: #include "sshkey.h"
32: #include "ssherr.h"
33: #include "ssh.h"
34: #include "digest.h"
35:
1.8 ! djm 36: /* Reuse some ED25519 internals */
! 37: extern struct sshkey_impl_funcs sshkey_ed25519_funcs;
! 38:
1.7 djm 39: static void
40: ssh_ed25519_sk_cleanup(struct sshkey *k)
41: {
1.8 ! djm 42: sshkey_sk_cleanup(k);
! 43: sshkey_ed25519_funcs.cleanup(k);
! 44: }
! 45:
! 46: static int
! 47: ssh_ed25519_sk_equal(const struct sshkey *a, const struct sshkey *b)
! 48: {
! 49: if (!sshkey_sk_fields_equal(a, b))
! 50: return 0;
! 51: if (!sshkey_ed25519_funcs.equal(a, b))
! 52: return 0;
! 53: return 1;
1.7 djm 54: }
55:
1.1 markus 56: int
57: ssh_ed25519_sk_verify(const struct sshkey *key,
58: const u_char *signature, size_t signaturelen,
1.3 djm 59: const u_char *data, size_t datalen, u_int compat,
60: struct sshkey_sig_details **detailsp)
1.1 markus 61: {
62: struct sshbuf *b = NULL;
63: struct sshbuf *encoded = NULL;
64: char *ktype = NULL;
65: const u_char *sigblob;
66: const u_char *sm;
67: u_char *m = NULL;
68: u_char apphash[32];
69: u_char msghash[32];
70: u_char sig_flags;
71: u_int sig_counter;
72: size_t len;
73: unsigned long long smlen = 0, mlen = 0;
74: int r = SSH_ERR_INTERNAL_ERROR;
75: int ret;
1.3 djm 76: struct sshkey_sig_details *details = NULL;
77:
78: if (detailsp != NULL)
79: *detailsp = NULL;
1.1 markus 80:
81: if (key == NULL ||
82: sshkey_type_plain(key->type) != KEY_ED25519_SK ||
83: key->ed25519_pk == NULL ||
84: signature == NULL || signaturelen == 0)
85: return SSH_ERR_INVALID_ARGUMENT;
86:
87: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
88: return SSH_ERR_ALLOC_FAIL;
89: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
1.2 markus 90: sshbuf_get_string_direct(b, &sigblob, &len) != 0 ||
91: sshbuf_get_u8(b, &sig_flags) != 0 ||
92: sshbuf_get_u32(b, &sig_counter) != 0) {
1.1 markus 93: r = SSH_ERR_INVALID_FORMAT;
94: goto out;
95: }
1.4 djm 96: #ifdef DEBUG_SK
97: fprintf(stderr, "%s: data:\n", __func__);
98: /* sshbuf_dump_data(data, datalen, stderr); */
99: fprintf(stderr, "%s: sigblob:\n", __func__);
100: sshbuf_dump_data(sigblob, len, stderr);
101: fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
102: __func__, sig_flags, sig_counter);
103: #endif
1.1 markus 104: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
105: r = SSH_ERR_KEY_TYPE_MISMATCH;
106: goto out;
107: }
108: if (sshbuf_len(b) != 0) {
109: r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
110: goto out;
111: }
112: if (len > crypto_sign_ed25519_BYTES) {
113: r = SSH_ERR_INVALID_FORMAT;
114: goto out;
115: }
116: if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
117: strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
118: ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
119: msghash, sizeof(msghash)) != 0) {
120: r = SSH_ERR_INVALID_ARGUMENT;
121: goto out;
122: }
1.4 djm 123: #ifdef DEBUG_SK
124: fprintf(stderr, "%s: hashed application:\n", __func__);
125: sshbuf_dump_data(apphash, sizeof(apphash), stderr);
126: fprintf(stderr, "%s: hashed message:\n", __func__);
127: sshbuf_dump_data(msghash, sizeof(msghash), stderr);
128: #endif
1.3 djm 129: if ((details = calloc(1, sizeof(*details))) == NULL) {
130: r = SSH_ERR_ALLOC_FAIL;
131: goto out;
132: }
133: details->sk_counter = sig_counter;
134: details->sk_flags = sig_flags;
1.1 markus 135: if ((encoded = sshbuf_new()) == NULL) {
136: r = SSH_ERR_ALLOC_FAIL;
137: goto out;
138: }
139: if (sshbuf_put(encoded, sigblob, len) != 0 ||
140: sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
141: sshbuf_put_u8(encoded, sig_flags) != 0 ||
142: sshbuf_put_u32(encoded, sig_counter) != 0 ||
143: sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
144: r = SSH_ERR_ALLOC_FAIL;
145: goto out;
146: }
1.4 djm 147: #ifdef DEBUG_SK
148: fprintf(stderr, "%s: signed buf:\n", __func__);
149: sshbuf_dump(encoded, stderr);
150: #endif
1.1 markus 151: sm = sshbuf_ptr(encoded);
152: smlen = sshbuf_len(encoded);
153: mlen = smlen;
154: if ((m = malloc(smlen)) == NULL) {
155: r = SSH_ERR_ALLOC_FAIL;
156: goto out;
157: }
158: if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
159: key->ed25519_pk)) != 0) {
1.6 djm 160: debug2_f("crypto_sign_ed25519_open failed: %d", ret);
1.1 markus 161: }
162: if (ret != 0 || mlen != smlen - len) {
163: r = SSH_ERR_SIGNATURE_INVALID;
164: goto out;
165: }
166: /* XXX compare 'm' and 'sm + len' ? */
167: /* success */
168: r = 0;
1.3 djm 169: if (detailsp != NULL) {
170: *detailsp = details;
171: details = NULL;
172: }
1.1 markus 173: out:
1.5 jsg 174: if (m != NULL)
175: freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
1.3 djm 176: sshkey_sig_details_free(details);
1.1 markus 177: sshbuf_free(b);
178: sshbuf_free(encoded);
179: free(ktype);
180: return r;
181: }
1.7 djm 182:
183: static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = {
184: /* .size = */ NULL,
185: /* .alloc = */ NULL,
186: /* .cleanup = */ ssh_ed25519_sk_cleanup,
1.8 ! djm 187: /* .equal = */ ssh_ed25519_sk_equal,
1.7 djm 188: };
189:
190: const struct sshkey_impl sshkey_ed25519_sk_impl = {
191: /* .name = */ "sk-ssh-ed25519@openssh.com",
192: /* .shortname = */ "ED25519-SK",
193: /* .sigalg = */ NULL,
194: /* .type = */ KEY_ED25519_SK,
195: /* .nid = */ 0,
196: /* .cert = */ 0,
197: /* .sigonly = */ 0,
198: /* .keybits = */ 256,
199: /* .funcs = */ &sshkey_ed25519_sk_funcs,
200: };
201:
202: const struct sshkey_impl sshkey_ed25519_sk_cert_impl = {
203: /* .name = */ "sk-ssh-ed25519-cert-v01@openssh.com",
204: /* .shortname = */ "ED25519-SK-CERT",
205: /* .sigalg = */ NULL,
206: /* .type = */ KEY_ED25519_SK_CERT,
207: /* .nid = */ 0,
208: /* .cert = */ 1,
209: /* .sigonly = */ 0,
210: /* .keybits = */ 256,
211: /* .funcs = */ &sshkey_ed25519_sk_funcs,
212: };
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