| /* $OpenBSD: ssh-ed25519-sk.c,v 1.15 2022/10/28 00:44:44 djm 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 DEBUG_SK 1 */ |
| |
| #include "includes.h" |
| |
| #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" |
| |
| /* Reuse some ED25519 internals */ |
| extern struct sshkey_impl_funcs sshkey_ed25519_funcs; |
| |
| static void |
| ssh_ed25519_sk_cleanup(struct sshkey *k) |
| { |
| sshkey_sk_cleanup(k); |
| sshkey_ed25519_funcs.cleanup(k); |
| } |
| |
| static int |
| ssh_ed25519_sk_equal(const struct sshkey *a, const struct sshkey *b) |
| { |
| if (!sshkey_sk_fields_equal(a, b)) |
| return 0; |
| if (!sshkey_ed25519_funcs.equal(a, b)) |
| return 0; |
| return 1; |
| } |
| |
| static int |
| ssh_ed25519_sk_serialize_public(const struct sshkey *key, struct sshbuf *b, |
| enum sshkey_serialize_rep opts) |
| { |
| int r; |
| |
| if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0) |
| return r; |
| if ((r = sshkey_serialize_sk(key, b)) != 0) |
| return r; |
| |
| return 0; |
| } |
| |
| static int |
| ssh_ed25519_sk_serialize_private(const struct sshkey *key, struct sshbuf *b, |
| enum sshkey_serialize_rep opts) |
| { |
| int r; |
| |
| if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0) |
| return r; |
| if ((r = sshkey_serialize_private_sk(key, b)) != 0) |
| return r; |
| |
| return 0; |
| } |
| |
| static int |
| ssh_ed25519_sk_copy_public(const struct sshkey *from, struct sshkey *to) |
| { |
| int r; |
| |
| if ((r = sshkey_ed25519_funcs.copy_public(from, to)) != 0) |
| return r; |
| if ((r = sshkey_copy_public_sk(from, to)) != 0) |
| return r; |
| return 0; |
| } |
| |
| static int |
| ssh_ed25519_sk_deserialize_public(const char *ktype, struct sshbuf *b, |
| struct sshkey *key) |
| { |
| int r; |
| |
| if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0) |
| return r; |
| if ((r = sshkey_deserialize_sk(b, key)) != 0) |
| return r; |
| return 0; |
| } |
| |
| static int |
| ssh_ed25519_sk_deserialize_private(const char *ktype, struct sshbuf *b, |
| struct sshkey *key) |
| { |
| int r; |
| |
| if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0) |
| return r; |
| if ((r = sshkey_private_deserialize_sk(b, key)) != 0) |
| return r; |
| return 0; |
| } |
| |
| static int |
| ssh_ed25519_sk_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) |
| { |
| 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; |
| struct sshkey_sig_details *details = NULL; |
| |
| if (detailsp != NULL) |
| *detailsp = NULL; |
| |
| if (key == NULL || |
| sshkey_type_plain(key->type) != KEY_ED25519_SK || |
| key->ed25519_pk == NULL || |
| sig == NULL || siglen == 0) |
| return SSH_ERR_INVALID_ARGUMENT; |
| |
| if ((b = sshbuf_from(sig, siglen)) == 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; |
| } |
| #ifdef DEBUG_SK |
| fprintf(stderr, "%s: data:\n", __func__); |
| /* sshbuf_dump_data(data, datalen, stderr); */ |
| fprintf(stderr, "%s: sigblob:\n", __func__); |
| sshbuf_dump_data(sigblob, len, stderr); |
| fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n", |
| __func__, sig_flags, sig_counter); |
| #endif |
| 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, dlen, |
| msghash, sizeof(msghash)) != 0) { |
| r = SSH_ERR_INVALID_ARGUMENT; |
| goto out; |
| } |
| #ifdef DEBUG_SK |
| fprintf(stderr, "%s: hashed application:\n", __func__); |
| sshbuf_dump_data(apphash, sizeof(apphash), stderr); |
| fprintf(stderr, "%s: hashed message:\n", __func__); |
| sshbuf_dump_data(msghash, sizeof(msghash), stderr); |
| #endif |
| if ((details = calloc(1, sizeof(*details))) == NULL) { |
| r = SSH_ERR_ALLOC_FAIL; |
| goto out; |
| } |
| details->sk_counter = sig_counter; |
| details->sk_flags = sig_flags; |
| 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; |
| } |
| #ifdef DEBUG_SK |
| fprintf(stderr, "%s: signed buf:\n", __func__); |
| sshbuf_dump(encoded, stderr); |
| #endif |
| 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_f("crypto_sign_ed25519_open failed: %d", ret); |
| } |
| if (ret != 0 || mlen != smlen - len) { |
| r = SSH_ERR_SIGNATURE_INVALID; |
| goto out; |
| } |
| /* XXX compare 'm' and 'sm + len' ? */ |
| /* success */ |
| r = 0; |
| if (detailsp != NULL) { |
| *detailsp = details; |
| details = NULL; |
| } |
| out: |
| if (m != NULL) |
| freezero(m, smlen); /* NB mlen may be invalid if r != 0 */ |
| sshkey_sig_details_free(details); |
| sshbuf_free(b); |
| sshbuf_free(encoded); |
| free(ktype); |
| return r; |
| } |
| |
| static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = { |
| /* .size = */ NULL, |
| /* .alloc = */ NULL, |
| /* .cleanup = */ ssh_ed25519_sk_cleanup, |
| /* .equal = */ ssh_ed25519_sk_equal, |
| /* .ssh_serialize_public = */ ssh_ed25519_sk_serialize_public, |
| /* .ssh_deserialize_public = */ ssh_ed25519_sk_deserialize_public, |
| /* .ssh_serialize_private = */ ssh_ed25519_sk_serialize_private, |
| /* .ssh_deserialize_private = */ ssh_ed25519_sk_deserialize_private, |
| /* .generate = */ NULL, |
| /* .copy_public = */ ssh_ed25519_sk_copy_public, |
| /* .sign = */ NULL, |
| /* .verify = */ ssh_ed25519_sk_verify, |
| }; |
| |
| const struct sshkey_impl sshkey_ed25519_sk_impl = { |
| /* .name = */ "sk-ssh-ed25519@openssh.com", |
| /* .shortname = */ "ED25519-SK", |
| /* .sigalg = */ NULL, |
| /* .type = */ KEY_ED25519_SK, |
| /* .nid = */ 0, |
| /* .cert = */ 0, |
| /* .sigonly = */ 0, |
| /* .keybits = */ 256, |
| /* .funcs = */ &sshkey_ed25519_sk_funcs, |
| }; |
| |
| const struct sshkey_impl sshkey_ed25519_sk_cert_impl = { |
| /* .name = */ "sk-ssh-ed25519-cert-v01@openssh.com", |
| /* .shortname = */ "ED25519-SK-CERT", |
| /* .sigalg = */ NULL, |
| /* .type = */ KEY_ED25519_SK_CERT, |
| /* .nid = */ 0, |
| /* .cert = */ 1, |
| /* .sigonly = */ 0, |
| /* .keybits = */ 256, |
| /* .funcs = */ &sshkey_ed25519_sk_funcs, |
| }; |