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/* $OpenBSD: ssh-ecdsa.c,v 1.13 2016/04/21 06:08:02 djm Exp $ */ |
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/* |
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* Copyright (c) 2000 Markus Friedl. All rights reserved. |
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* Copyright (c) 2010 Damien Miller. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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#include <sys/types.h> |
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#include <openssl/bn.h> |
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#include <openssl/ec.h> |
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#include <openssl/ecdsa.h> |
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#include <openssl/evp.h> |
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#include <string.h> |
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#include "sshbuf.h" |
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#include "ssherr.h" |
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#include "digest.h" |
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#define SSHKEY_INTERNAL |
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#include "sshkey.h" |
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/* ARGSUSED */ |
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int |
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ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, |
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const u_char *data, size_t datalen, u_int compat) |
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{ |
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ECDSA_SIG *sig = NULL; |
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int hash_alg; |
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u_char digest[SSH_DIGEST_MAX_LENGTH]; |
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size_t len, dlen; |
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struct sshbuf *b = NULL, *bb = NULL; |
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int ret = SSH_ERR_INTERNAL_ERROR; |
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if (lenp != NULL) |
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*lenp = 0; |
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if (sigp != NULL) |
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*sigp = NULL; |
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if (key == NULL || key->ecdsa == NULL || |
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sshkey_type_plain(key->type) != KEY_ECDSA) |
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return SSH_ERR_INVALID_ARGUMENT; |
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if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 || |
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(dlen = ssh_digest_bytes(hash_alg)) == 0) |
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return SSH_ERR_INTERNAL_ERROR; |
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if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
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digest, sizeof(digest))) != 0) |
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goto out; |
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if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) { |
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ret = SSH_ERR_LIBCRYPTO_ERROR; |
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goto out; |
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} |
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if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) { |
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ret = SSH_ERR_ALLOC_FAIL; |
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goto out; |
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} |
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if ((ret = sshbuf_put_bignum2(bb, sig->r)) != 0 || |
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(ret = sshbuf_put_bignum2(bb, sig->s)) != 0) |
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goto out; |
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if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 || |
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(ret = sshbuf_put_stringb(b, bb)) != 0) |
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goto out; |
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len = sshbuf_len(b); |
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if (sigp != NULL) { |
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if ((*sigp = malloc(len)) == NULL) { |
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ret = SSH_ERR_ALLOC_FAIL; |
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goto out; |
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} |
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memcpy(*sigp, sshbuf_ptr(b), len); |
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} |
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if (lenp != NULL) |
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*lenp = len; |
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ret = 0; |
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out: |
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explicit_bzero(digest, sizeof(digest)); |
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sshbuf_free(b); |
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sshbuf_free(bb); |
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if (sig != NULL) |
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ECDSA_SIG_free(sig); |
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return ret; |
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} |
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/* ARGSUSED */ |
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int |
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ssh_ecdsa_verify(const struct sshkey *key, |
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const u_char *signature, size_t signaturelen, |
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const u_char *data, size_t datalen, u_int compat) |
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{ |
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ECDSA_SIG *sig = NULL; |
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int hash_alg; |
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u_char digest[SSH_DIGEST_MAX_LENGTH]; |
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size_t dlen; |
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int ret = SSH_ERR_INTERNAL_ERROR; |
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struct sshbuf *b = NULL, *sigbuf = NULL; |
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char *ktype = NULL; |
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if (key == NULL || key->ecdsa == NULL || |
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sshkey_type_plain(key->type) != KEY_ECDSA || |
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signature == NULL || signaturelen == 0) |
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return SSH_ERR_INVALID_ARGUMENT; |
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if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 || |
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(dlen = ssh_digest_bytes(hash_alg)) == 0) |
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return SSH_ERR_INTERNAL_ERROR; |
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/* fetch signature */ |
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if ((b = sshbuf_from(signature, signaturelen)) == NULL) |
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return SSH_ERR_ALLOC_FAIL; |
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if (sshbuf_get_cstring(b, &ktype, NULL) != 0 || |
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sshbuf_froms(b, &sigbuf) != 0) { |
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ret = SSH_ERR_INVALID_FORMAT; |
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goto out; |
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} |
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if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) { |
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ret = SSH_ERR_KEY_TYPE_MISMATCH; |
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goto out; |
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} |
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if (sshbuf_len(b) != 0) { |
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ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
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goto out; |
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} |
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/* parse signature */ |
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if ((sig = ECDSA_SIG_new()) == NULL) { |
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ret = SSH_ERR_ALLOC_FAIL; |
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goto out; |
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} |
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if (sshbuf_get_bignum2(sigbuf, sig->r) != 0 || |
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sshbuf_get_bignum2(sigbuf, sig->s) != 0) { |
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ret = SSH_ERR_INVALID_FORMAT; |
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goto out; |
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} |
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if (sshbuf_len(sigbuf) != 0) { |
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ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
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goto out; |
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} |
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if ((ret = ssh_digest_memory(hash_alg, data, datalen, |
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digest, sizeof(digest))) != 0) |
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goto out; |
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switch (ECDSA_do_verify(digest, dlen, sig, key->ecdsa)) { |
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case 1: |
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ret = 0; |
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break; |
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case 0: |
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ret = SSH_ERR_SIGNATURE_INVALID; |
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goto out; |
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default: |
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ret = SSH_ERR_LIBCRYPTO_ERROR; |
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goto out; |
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} |
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out: |
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explicit_bzero(digest, sizeof(digest)); |
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sshbuf_free(sigbuf); |
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sshbuf_free(b); |
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if (sig != NULL) |
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ECDSA_SIG_free(sig); |
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free(ktype); |
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return ret; |
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} |