/* $OpenBSD: ssh-ed25519.c,v 1.19 2022/10/28 00:44:44 djm Exp $ */ /* * Copyright (c) 2013 Markus Friedl * * 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 "includes.h" __RCSID("$NetBSD: ssh-ed25519.c,v 1.9.2.1 2023/08/11 15:36:40 martin Exp $"); #include #include #include "crypto_api.h" #include #include #include "log.h" #include "sshbuf.h" #include "sshkey.h" #include "ssherr.h" #include "ssh.h" static void ssh_ed25519_cleanup(struct sshkey *k) { freezero(k->ed25519_pk, ED25519_PK_SZ); freezero(k->ed25519_sk, ED25519_SK_SZ); k->ed25519_pk = NULL; k->ed25519_sk = NULL; } static int ssh_ed25519_equal(const struct sshkey *a, const struct sshkey *b) { if (a->ed25519_pk == NULL || b->ed25519_pk == NULL) return 0; if (memcmp(a->ed25519_pk, b->ed25519_pk, ED25519_PK_SZ) != 0) return 0; return 1; } static int ssh_ed25519_serialize_public(const struct sshkey *key, struct sshbuf *b, enum sshkey_serialize_rep opts) { int r; if (key->ed25519_pk == NULL) return SSH_ERR_INVALID_ARGUMENT; if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0) return r; return 0; } static int ssh_ed25519_serialize_private(const struct sshkey *key, struct sshbuf *b, enum sshkey_serialize_rep opts) { int r; if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0 || (r = sshbuf_put_string(b, key->ed25519_sk, ED25519_SK_SZ)) != 0) return r; return 0; } static int ssh_ed25519_generate(struct sshkey *k, int bits) { if ((k->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL || (k->ed25519_sk = malloc(ED25519_SK_SZ)) == NULL) return SSH_ERR_ALLOC_FAIL; crypto_sign_ed25519_keypair(k->ed25519_pk, k->ed25519_sk); return 0; } static int ssh_ed25519_copy_public(const struct sshkey *from, struct sshkey *to) { if (from->ed25519_pk == NULL) return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */ if ((to->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL) return SSH_ERR_ALLOC_FAIL; memcpy(to->ed25519_pk, from->ed25519_pk, ED25519_PK_SZ); return 0; } static int ssh_ed25519_deserialize_public(const char *ktype, struct sshbuf *b, struct sshkey *key) { u_char *pk = NULL; size_t len = 0; int r; if ((r = sshbuf_get_string(b, &pk, &len)) != 0) return r; if (len != ED25519_PK_SZ) { freezero(pk, len); return SSH_ERR_INVALID_FORMAT; } key->ed25519_pk = pk; return 0; } static int ssh_ed25519_deserialize_private(const char *ktype, struct sshbuf *b, struct sshkey *key) { int r; size_t sklen = 0; u_char *ed25519_sk = NULL; if ((r = ssh_ed25519_deserialize_public(NULL, b, key)) != 0) goto out; if ((r = sshbuf_get_string(b, &ed25519_sk, &sklen)) != 0) goto out; if (sklen != ED25519_SK_SZ) { r = SSH_ERR_INVALID_FORMAT; goto out; } key->ed25519_sk = ed25519_sk; ed25519_sk = NULL; /* transferred */ /* success */ r = 0; out: freezero(ed25519_sk, sklen); return r; } static int ssh_ed25519_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) { u_char *sig = NULL; size_t slen = 0, len; unsigned long long smlen; int r, ret; struct sshbuf *b = NULL; if (lenp != NULL) *lenp = 0; if (sigp != NULL) *sigp = NULL; if (key == NULL || sshkey_type_plain(key->type) != KEY_ED25519 || key->ed25519_sk == NULL || datalen >= INT_MAX - crypto_sign_ed25519_BYTES) return SSH_ERR_INVALID_ARGUMENT; smlen = slen = datalen + crypto_sign_ed25519_BYTES; if ((sig = malloc(slen)) == NULL) return SSH_ERR_ALLOC_FAIL; if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen, key->ed25519_sk)) != 0 || smlen <= datalen) { r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */ goto out; } /* encode signature */ if ((b = sshbuf_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 || (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0) goto out; len = sshbuf_len(b); if (sigp != NULL) { if ((*sigp = malloc(len)) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } memcpy(*sigp, sshbuf_ptr(b), len); } if (lenp != NULL) *lenp = len; /* success */ r = 0; out: sshbuf_free(b); if (sig != NULL) freezero(sig, slen); return r; } static int ssh_ed25519_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; char *ktype = NULL; const u_char *sigblob; u_char *sm = NULL, *m = NULL; size_t len; unsigned long long smlen = 0, mlen = 0; int r, ret; if (key == NULL || sshkey_type_plain(key->type) != KEY_ED25519 || key->ed25519_pk == NULL || dlen >= INT_MAX - crypto_sign_ed25519_BYTES || sig == NULL || siglen == 0) return SSH_ERR_INVALID_ARGUMENT; if ((b = sshbuf_from(sig, siglen)) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 || (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0) goto out; if (strcmp("ssh-ed25519", 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 (dlen >= SIZE_MAX - len) { r = SSH_ERR_INVALID_ARGUMENT; goto out; } smlen = len + dlen; mlen = smlen; if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } memcpy(sm, sigblob, len); memcpy(sm+len, data, dlen); 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 != dlen) { r = SSH_ERR_SIGNATURE_INVALID; goto out; } /* XXX compare 'm' and 'data' ? */ /* success */ r = 0; out: if (sm != NULL) freezero(sm, smlen); if (m != NULL) freezero(m, smlen); /* NB mlen may be invalid if r != 0 */ sshbuf_free(b); free(ktype); return r; } /* NB. not static; used by ED25519-SK */ const struct sshkey_impl_funcs sshkey_ed25519_funcs = { /* .size = */ NULL, /* .alloc = */ NULL, /* .cleanup = */ ssh_ed25519_cleanup, /* .equal = */ ssh_ed25519_equal, /* .ssh_serialize_public = */ ssh_ed25519_serialize_public, /* .ssh_deserialize_public = */ ssh_ed25519_deserialize_public, /* .ssh_serialize_private = */ ssh_ed25519_serialize_private, /* .ssh_deserialize_private = */ ssh_ed25519_deserialize_private, /* .generate = */ ssh_ed25519_generate, /* .copy_public = */ ssh_ed25519_copy_public, /* .sign = */ ssh_ed25519_sign, /* .verify = */ ssh_ed25519_verify, }; const struct sshkey_impl sshkey_ed25519_impl = { /* .name = */ "ssh-ed25519", /* .shortname = */ "ED25519", /* .sigalg = */ NULL, /* .type = */ KEY_ED25519, /* .nid = */ 0, /* .cert = */ 0, /* .sigonly = */ 0, /* .keybits = */ 256, /* .funcs = */ &sshkey_ed25519_funcs, }; const struct sshkey_impl sshkey_ed25519_cert_impl = { /* .name = */ "ssh-ed25519-cert-v01@openssh.com", /* .shortname = */ "ED25519-CERT", /* .sigalg = */ NULL, /* .type = */ KEY_ED25519_CERT, /* .nid = */ 0, /* .cert = */ 1, /* .sigonly = */ 0, /* .keybits = */ 256, /* .funcs = */ &sshkey_ed25519_funcs, };