| /* $OpenBSD: ssh-ed25519-sk.c,v 1.2 2019/11/12 19:34:40 markus Exp $ */ |
| /* |
| * Copyright (c) 2019 Markus Friedl. All rights reserved. |
| * |
| * Permission to use, copy, modify, and distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| */ |
| #define SSHKEY_INTERNAL |
| #include <sys/types.h> |
| #include <limits.h> |
| |
| #include "crypto_api.h" |
| |
| #include <string.h> |
| #include <stdarg.h> |
| |
| #include "log.h" |
| #include "sshbuf.h" |
| #include "sshkey.h" |
| #include "ssherr.h" |
| #include "ssh.h" |
| #include "digest.h" |
| |
| int |
| ssh_ed25519_sk_verify(const struct sshkey *key, |
| const u_char *signature, size_t signaturelen, |
| const u_char *data, size_t datalen, u_int compat) |
| { |
| struct sshbuf *b = NULL; |
| struct sshbuf *encoded = NULL; |
| char *ktype = NULL; |
| const u_char *sigblob; |
| const u_char *sm; |
| u_char *m = NULL; |
| u_char apphash[32]; |
| u_char msghash[32]; |
| u_char sig_flags; |
| u_int sig_counter; |
| size_t len; |
| unsigned long long smlen = 0, mlen = 0; |
| int r = SSH_ERR_INTERNAL_ERROR; |
| int ret; |
| |
| if (key == NULL || |
| sshkey_type_plain(key->type) != KEY_ED25519_SK || |
| key->ed25519_pk == NULL || |
| signature == NULL || signaturelen == 0) |
| return SSH_ERR_INVALID_ARGUMENT; |
| |
| if ((b = sshbuf_from(signature, signaturelen)) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| if (sshbuf_get_cstring(b, &ktype, NULL) != 0 || |
| sshbuf_get_string_direct(b, &sigblob, &len) != 0 || |
| sshbuf_get_u8(b, &sig_flags) != 0 || |
| sshbuf_get_u32(b, &sig_counter) != 0) { |
| r = SSH_ERR_INVALID_FORMAT; |
| goto out; |
| } |
| if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) { |
| r = SSH_ERR_KEY_TYPE_MISMATCH; |
| goto out; |
| } |
| if (sshbuf_len(b) != 0) { |
| r = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
| goto out; |
| } |
| if (len > crypto_sign_ed25519_BYTES) { |
| r = SSH_ERR_INVALID_FORMAT; |
| goto out; |
| } |
| if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application, |
| strlen(key->sk_application), apphash, sizeof(apphash)) != 0 || |
| ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen, |
| msghash, sizeof(msghash)) != 0) { |
| r = SSH_ERR_INVALID_ARGUMENT; |
| goto out; |
| } |
| if ((encoded = sshbuf_new()) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if (sshbuf_put(encoded, sigblob, len) != 0 || |
| sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 || |
| sshbuf_put_u8(encoded, sig_flags) != 0 || |
| sshbuf_put_u32(encoded, sig_counter) != 0 || |
| sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| sm = sshbuf_ptr(encoded); |
| smlen = sshbuf_len(encoded); |
| mlen = smlen; |
| if ((m = malloc(smlen)) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen, |
| key->ed25519_pk)) != 0) { |
| debug2("%s: crypto_sign_ed25519_open failed: %d", |
| __func__, ret); |
| } |
| if (ret != 0 || mlen != smlen - len) { |
| r = SSH_ERR_SIGNATURE_INVALID; |
| goto out; |
| } |
| /* XXX compare 'm' and 'sm + len' ? */ |
| /* success */ |
| r = 0; |
| out: |
| if (m != NULL) { |
| explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */ |
| free(m); |
| } |
| sshbuf_free(b); |
| sshbuf_free(encoded); |
| free(ktype); |
| return r; |
| } |