| /* $OpenBSD: ssh-dss.c,v 1.49 2023/03/05 05:34:09 dtucker Exp $ */ |
| /* |
| * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #ifdef WITH_OPENSSL |
| |
| #include <sys/types.h> |
| |
| #include <openssl/bn.h> |
| #include <openssl/dsa.h> |
| #include <openssl/evp.h> |
| |
| #include <stdarg.h> |
| #include <string.h> |
| |
| #include "sshbuf.h" |
| #include "ssherr.h" |
| #include "digest.h" |
| #define SSHKEY_INTERNAL |
| #include "sshkey.h" |
| |
| #include "openbsd-compat/openssl-compat.h" |
| |
| #define INTBLOB_LEN 20 |
| #define SIGBLOB_LEN (2*INTBLOB_LEN) |
| |
| static u_int |
| ssh_dss_size(const struct sshkey *key) |
| { |
| const BIGNUM *dsa_p; |
| |
| if (key->dsa == NULL) |
| return 0; |
| DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL); |
| return BN_num_bits(dsa_p); |
| } |
| |
| static int |
| ssh_dss_alloc(struct sshkey *k) |
| { |
| if ((k->dsa = DSA_new()) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| return 0; |
| } |
| |
| static void |
| ssh_dss_cleanup(struct sshkey *k) |
| { |
| DSA_free(k->dsa); |
| k->dsa = NULL; |
| } |
| |
| static int |
| ssh_dss_equal(const struct sshkey *a, const struct sshkey *b) |
| { |
| const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a; |
| const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b; |
| |
| if (a->dsa == NULL || b->dsa == NULL) |
| return 0; |
| DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a); |
| DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b); |
| DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL); |
| DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL); |
| if (dsa_p_a == NULL || dsa_p_b == NULL || |
| dsa_q_a == NULL || dsa_q_b == NULL || |
| dsa_g_a == NULL || dsa_g_b == NULL || |
| dsa_pub_key_a == NULL || dsa_pub_key_b == NULL) |
| return 0; |
| if (BN_cmp(dsa_p_a, dsa_p_b) != 0) |
| return 0; |
| if (BN_cmp(dsa_q_a, dsa_q_b) != 0) |
| return 0; |
| if (BN_cmp(dsa_g_a, dsa_g_b) != 0) |
| return 0; |
| if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0) |
| return 0; |
| return 1; |
| } |
| |
| static int |
| ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b, |
| enum sshkey_serialize_rep opts) |
| { |
| int r; |
| const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key; |
| |
| if (key->dsa == NULL) |
| return SSH_ERR_INVALID_ARGUMENT; |
| DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g); |
| DSA_get0_key(key->dsa, &dsa_pub_key, NULL); |
| if (dsa_p == NULL || dsa_q == NULL || |
| dsa_g == NULL || dsa_pub_key == NULL) |
| return SSH_ERR_INTERNAL_ERROR; |
| if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 || |
| (r = sshbuf_put_bignum2(b, dsa_q)) != 0 || |
| (r = sshbuf_put_bignum2(b, dsa_g)) != 0 || |
| (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0) |
| return r; |
| |
| return 0; |
| } |
| |
| static int |
| ssh_dss_serialize_private(const struct sshkey *key, struct sshbuf *b, |
| enum sshkey_serialize_rep opts) |
| { |
| int r; |
| const BIGNUM *dsa_priv_key; |
| |
| DSA_get0_key(key->dsa, NULL, &dsa_priv_key); |
| if (!sshkey_is_cert(key)) { |
| if ((r = ssh_dss_serialize_public(key, b, opts)) != 0) |
| return r; |
| } |
| if ((r = sshbuf_put_bignum2(b, dsa_priv_key)) != 0) |
| return r; |
| |
| return 0; |
| } |
| |
| static int |
| ssh_dss_generate(struct sshkey *k, int bits) |
| { |
| DSA *private; |
| |
| if (bits != 1024) |
| return SSH_ERR_KEY_LENGTH; |
| if ((private = DSA_new()) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL, |
| NULL, NULL) || !DSA_generate_key(private)) { |
| DSA_free(private); |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } |
| k->dsa = private; |
| return 0; |
| } |
| |
| static int |
| ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to) |
| { |
| const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key; |
| BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL; |
| BIGNUM *dsa_pub_key_dup = NULL; |
| int r = SSH_ERR_INTERNAL_ERROR; |
| |
| DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g); |
| DSA_get0_key(from->dsa, &dsa_pub_key, NULL); |
| if ((dsa_p_dup = BN_dup(dsa_p)) == NULL || |
| (dsa_q_dup = BN_dup(dsa_q)) == NULL || |
| (dsa_g_dup = BN_dup(dsa_g)) == NULL || |
| (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) { |
| r = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */ |
| if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) { |
| r = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| dsa_pub_key_dup = NULL; /* transferred */ |
| /* success */ |
| r = 0; |
| out: |
| BN_clear_free(dsa_p_dup); |
| BN_clear_free(dsa_q_dup); |
| BN_clear_free(dsa_g_dup); |
| BN_clear_free(dsa_pub_key_dup); |
| return r; |
| } |
| |
| static int |
| ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b, |
| struct sshkey *key) |
| { |
| int ret = SSH_ERR_INTERNAL_ERROR; |
| BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL; |
| |
| if (sshbuf_get_bignum2(b, &dsa_p) != 0 || |
| sshbuf_get_bignum2(b, &dsa_q) != 0 || |
| sshbuf_get_bignum2(b, &dsa_g) != 0 || |
| sshbuf_get_bignum2(b, &dsa_pub_key) != 0) { |
| ret = SSH_ERR_INVALID_FORMAT; |
| goto out; |
| } |
| if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| dsa_p = dsa_q = dsa_g = NULL; /* transferred */ |
| if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| dsa_pub_key = NULL; /* transferred */ |
| #ifdef DEBUG_PK |
| DSA_print_fp(stderr, key->dsa, 8); |
| #endif |
| /* success */ |
| ret = 0; |
| out: |
| BN_clear_free(dsa_p); |
| BN_clear_free(dsa_q); |
| BN_clear_free(dsa_g); |
| BN_clear_free(dsa_pub_key); |
| return ret; |
| } |
| |
| static int |
| ssh_dss_deserialize_private(const char *ktype, struct sshbuf *b, |
| struct sshkey *key) |
| { |
| int r; |
| BIGNUM *dsa_priv_key = NULL; |
| |
| if (!sshkey_is_cert(key)) { |
| if ((r = ssh_dss_deserialize_public(ktype, b, key)) != 0) |
| return r; |
| } |
| |
| if ((r = sshbuf_get_bignum2(b, &dsa_priv_key)) != 0) |
| return r; |
| if (!DSA_set0_key(key->dsa, NULL, dsa_priv_key)) { |
| BN_clear_free(dsa_priv_key); |
| return SSH_ERR_LIBCRYPTO_ERROR; |
| } |
| return 0; |
| } |
| |
| static int |
| ssh_dss_sign(struct sshkey *key, |
| u_char **sigp, size_t *lenp, |
| const u_char *data, size_t datalen, |
| const char *alg, const char *sk_provider, const char *sk_pin, u_int compat) |
| { |
| DSA_SIG *sig = NULL; |
| const BIGNUM *sig_r, *sig_s; |
| u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN]; |
| size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1); |
| struct sshbuf *b = NULL; |
| int ret = SSH_ERR_INVALID_ARGUMENT; |
| |
| if (lenp != NULL) |
| *lenp = 0; |
| if (sigp != NULL) |
| *sigp = NULL; |
| |
| if (key == NULL || key->dsa == NULL || |
| sshkey_type_plain(key->type) != KEY_DSA) |
| return SSH_ERR_INVALID_ARGUMENT; |
| if (dlen == 0) |
| return SSH_ERR_INTERNAL_ERROR; |
| |
| if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen, |
| digest, sizeof(digest))) != 0) |
| goto out; |
| |
| if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| |
| DSA_SIG_get0(sig, &sig_r, &sig_s); |
| rlen = BN_num_bytes(sig_r); |
| slen = BN_num_bytes(sig_s); |
| if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { |
| ret = SSH_ERR_INTERNAL_ERROR; |
| goto out; |
| } |
| explicit_bzero(sigblob, SIGBLOB_LEN); |
| BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen); |
| BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen); |
| |
| if ((b = sshbuf_new()) == NULL) { |
| ret = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 || |
| (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0) |
| goto out; |
| |
| len = sshbuf_len(b); |
| if (sigp != NULL) { |
| if ((*sigp = malloc(len)) == NULL) { |
| ret = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| memcpy(*sigp, sshbuf_ptr(b), len); |
| } |
| if (lenp != NULL) |
| *lenp = len; |
| ret = 0; |
| out: |
| explicit_bzero(digest, sizeof(digest)); |
| DSA_SIG_free(sig); |
| sshbuf_free(b); |
| return ret; |
| } |
| |
| static int |
| ssh_dss_verify(const struct sshkey *key, |
| const u_char *sig, size_t siglen, |
| const u_char *data, size_t dlen, const char *alg, u_int compat, |
| struct sshkey_sig_details **detailsp) |
| { |
| DSA_SIG *dsig = NULL; |
| BIGNUM *sig_r = NULL, *sig_s = NULL; |
| u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL; |
| size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1); |
| int ret = SSH_ERR_INTERNAL_ERROR; |
| struct sshbuf *b = NULL; |
| char *ktype = NULL; |
| |
| if (key == NULL || key->dsa == NULL || |
| sshkey_type_plain(key->type) != KEY_DSA || |
| sig == NULL || siglen == 0) |
| return SSH_ERR_INVALID_ARGUMENT; |
| if (hlen == 0) |
| return SSH_ERR_INTERNAL_ERROR; |
| |
| /* fetch signature */ |
| if ((b = sshbuf_from(sig, siglen)) == NULL) |
| return SSH_ERR_ALLOC_FAIL; |
| if (sshbuf_get_cstring(b, &ktype, NULL) != 0 || |
| sshbuf_get_string(b, &sigblob, &len) != 0) { |
| ret = SSH_ERR_INVALID_FORMAT; |
| goto out; |
| } |
| if (strcmp("ssh-dss", ktype) != 0) { |
| ret = SSH_ERR_KEY_TYPE_MISMATCH; |
| goto out; |
| } |
| if (sshbuf_len(b) != 0) { |
| ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; |
| goto out; |
| } |
| |
| if (len != SIGBLOB_LEN) { |
| ret = SSH_ERR_INVALID_FORMAT; |
| goto out; |
| } |
| |
| /* parse signature */ |
| if ((dsig = DSA_SIG_new()) == NULL || |
| (sig_r = BN_new()) == NULL || |
| (sig_s = BN_new()) == NULL) { |
| ret = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) || |
| (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| if (!DSA_SIG_set0(dsig, sig_r, sig_s)) { |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| sig_r = sig_s = NULL; /* transferred */ |
| |
| /* sha1 the data */ |
| if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen, |
| digest, sizeof(digest))) != 0) |
| goto out; |
| |
| switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) { |
| case 1: |
| ret = 0; |
| break; |
| case 0: |
| ret = SSH_ERR_SIGNATURE_INVALID; |
| goto out; |
| default: |
| ret = SSH_ERR_LIBCRYPTO_ERROR; |
| goto out; |
| } |
| |
| out: |
| explicit_bzero(digest, sizeof(digest)); |
| DSA_SIG_free(dsig); |
| BN_clear_free(sig_r); |
| BN_clear_free(sig_s); |
| sshbuf_free(b); |
| free(ktype); |
| if (sigblob != NULL) |
| freezero(sigblob, len); |
| return ret; |
| } |
| |
| static const struct sshkey_impl_funcs sshkey_dss_funcs = { |
| /* .size = */ ssh_dss_size, |
| /* .alloc = */ ssh_dss_alloc, |
| /* .cleanup = */ ssh_dss_cleanup, |
| /* .equal = */ ssh_dss_equal, |
| /* .ssh_serialize_public = */ ssh_dss_serialize_public, |
| /* .ssh_deserialize_public = */ ssh_dss_deserialize_public, |
| /* .ssh_serialize_private = */ ssh_dss_serialize_private, |
| /* .ssh_deserialize_private = */ ssh_dss_deserialize_private, |
| /* .generate = */ ssh_dss_generate, |
| /* .copy_public = */ ssh_dss_copy_public, |
| /* .sign = */ ssh_dss_sign, |
| /* .verify = */ ssh_dss_verify, |
| }; |
| |
| const struct sshkey_impl sshkey_dss_impl = { |
| /* .name = */ "ssh-dss", |
| /* .shortname = */ "DSA", |
| /* .sigalg = */ NULL, |
| /* .type = */ KEY_DSA, |
| /* .nid = */ 0, |
| /* .cert = */ 0, |
| /* .sigonly = */ 0, |
| /* .keybits = */ 0, |
| /* .funcs = */ &sshkey_dss_funcs, |
| }; |
| |
| const struct sshkey_impl sshkey_dsa_cert_impl = { |
| /* .name = */ "ssh-dss-cert-v01@openssh.com", |
| /* .shortname = */ "DSA-CERT", |
| /* .sigalg = */ NULL, |
| /* .type = */ KEY_DSA_CERT, |
| /* .nid = */ 0, |
| /* .cert = */ 1, |
| /* .sigonly = */ 0, |
| /* .keybits = */ 0, |
| /* .funcs = */ &sshkey_dss_funcs, |
| }; |
| #endif /* WITH_OPENSSL */ |