Annotation of src/usr.bin/ssh/ssh-ed25519-sk.c, Revision 1.4
1.4 ! djm 1: /* $OpenBSD: ssh-ed25519-sk.c,v 1.3 2019/11/25 00:51:37 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:
36: int
37: ssh_ed25519_sk_verify(const struct sshkey *key,
38: const u_char *signature, size_t signaturelen,
1.3 djm 39: const u_char *data, size_t datalen, u_int compat,
40: struct sshkey_sig_details **detailsp)
1.1 markus 41: {
42: struct sshbuf *b = NULL;
43: struct sshbuf *encoded = NULL;
44: char *ktype = NULL;
45: const u_char *sigblob;
46: const u_char *sm;
47: u_char *m = NULL;
48: u_char apphash[32];
49: u_char msghash[32];
50: u_char sig_flags;
51: u_int sig_counter;
52: size_t len;
53: unsigned long long smlen = 0, mlen = 0;
54: int r = SSH_ERR_INTERNAL_ERROR;
55: int ret;
1.3 djm 56: struct sshkey_sig_details *details = NULL;
57:
58: if (detailsp != NULL)
59: *detailsp = NULL;
1.1 markus 60:
61: if (key == NULL ||
62: sshkey_type_plain(key->type) != KEY_ED25519_SK ||
63: key->ed25519_pk == NULL ||
64: signature == NULL || signaturelen == 0)
65: return SSH_ERR_INVALID_ARGUMENT;
66:
67: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
68: return SSH_ERR_ALLOC_FAIL;
69: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
1.2 markus 70: sshbuf_get_string_direct(b, &sigblob, &len) != 0 ||
71: sshbuf_get_u8(b, &sig_flags) != 0 ||
72: sshbuf_get_u32(b, &sig_counter) != 0) {
1.1 markus 73: r = SSH_ERR_INVALID_FORMAT;
74: goto out;
75: }
1.4 ! djm 76: #ifdef DEBUG_SK
! 77: fprintf(stderr, "%s: data:\n", __func__);
! 78: /* sshbuf_dump_data(data, datalen, stderr); */
! 79: fprintf(stderr, "%s: sigblob:\n", __func__);
! 80: sshbuf_dump_data(sigblob, len, stderr);
! 81: fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
! 82: __func__, sig_flags, sig_counter);
! 83: #endif
1.1 markus 84: if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
85: r = SSH_ERR_KEY_TYPE_MISMATCH;
86: goto out;
87: }
88: if (sshbuf_len(b) != 0) {
89: r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
90: goto out;
91: }
92: if (len > crypto_sign_ed25519_BYTES) {
93: r = SSH_ERR_INVALID_FORMAT;
94: goto out;
95: }
96: if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
97: strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
98: ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
99: msghash, sizeof(msghash)) != 0) {
100: r = SSH_ERR_INVALID_ARGUMENT;
101: goto out;
102: }
1.4 ! djm 103: #ifdef DEBUG_SK
! 104: fprintf(stderr, "%s: hashed application:\n", __func__);
! 105: sshbuf_dump_data(apphash, sizeof(apphash), stderr);
! 106: fprintf(stderr, "%s: hashed message:\n", __func__);
! 107: sshbuf_dump_data(msghash, sizeof(msghash), stderr);
! 108: #endif
1.3 djm 109: if ((details = calloc(1, sizeof(*details))) == NULL) {
110: r = SSH_ERR_ALLOC_FAIL;
111: goto out;
112: }
113: details->sk_counter = sig_counter;
114: details->sk_flags = sig_flags;
1.1 markus 115: if ((encoded = sshbuf_new()) == NULL) {
116: r = SSH_ERR_ALLOC_FAIL;
117: goto out;
118: }
119: if (sshbuf_put(encoded, sigblob, len) != 0 ||
120: sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
121: sshbuf_put_u8(encoded, sig_flags) != 0 ||
122: sshbuf_put_u32(encoded, sig_counter) != 0 ||
123: sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
124: r = SSH_ERR_ALLOC_FAIL;
125: goto out;
126: }
1.4 ! djm 127: #ifdef DEBUG_SK
! 128: fprintf(stderr, "%s: signed buf:\n", __func__);
! 129: sshbuf_dump(encoded, stderr);
! 130: #endif
1.1 markus 131: sm = sshbuf_ptr(encoded);
132: smlen = sshbuf_len(encoded);
133: mlen = smlen;
134: if ((m = malloc(smlen)) == NULL) {
135: r = SSH_ERR_ALLOC_FAIL;
136: goto out;
137: }
138: if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
139: key->ed25519_pk)) != 0) {
140: debug2("%s: crypto_sign_ed25519_open failed: %d",
141: __func__, ret);
142: }
143: if (ret != 0 || mlen != smlen - len) {
144: r = SSH_ERR_SIGNATURE_INVALID;
145: goto out;
146: }
147: /* XXX compare 'm' and 'sm + len' ? */
148: /* success */
149: r = 0;
1.3 djm 150: if (detailsp != NULL) {
151: *detailsp = details;
152: details = NULL;
153: }
1.1 markus 154: out:
155: if (m != NULL) {
156: explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */
157: free(m);
158: }
1.3 djm 159: sshkey_sig_details_free(details);
1.1 markus 160: sshbuf_free(b);
161: sshbuf_free(encoded);
162: free(ktype);
163: return r;
164: }
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