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Annotation of src/usr.bin/ssh/ssh-ed25519-sk.c, Revision 1.1

1.1     ! markus      1: /* $OpenBSD: ssh-ed25519.c,v 1.7 2016/04/21 06:08:02 djm Exp $ */
        !             2: /*
        !             3:  * Copyright (c) 2019 Markus Friedl.  All rights reserved.
        !             4:  *
        !             5:  * Permission to use, copy, modify, and distribute this software for any
        !             6:  * purpose with or without fee is hereby granted, provided that the above
        !             7:  * copyright notice and this permission notice appear in all copies.
        !             8:  *
        !             9:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
        !            10:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
        !            11:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
        !            12:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
        !            13:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
        !            14:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
        !            15:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
        !            16:  */
        !            17: #define SSHKEY_INTERNAL
        !            18: #include <sys/types.h>
        !            19: #include <limits.h>
        !            20:
        !            21: #include "crypto_api.h"
        !            22:
        !            23: #include <string.h>
        !            24: #include <stdarg.h>
        !            25:
        !            26: #include "log.h"
        !            27: #include "sshbuf.h"
        !            28: #include "sshkey.h"
        !            29: #include "ssherr.h"
        !            30: #include "ssh.h"
        !            31: #include "digest.h"
        !            32:
        !            33: int
        !            34: ssh_ed25519_sk_verify(const struct sshkey *key,
        !            35:     const u_char *signature, size_t signaturelen,
        !            36:     const u_char *data, size_t datalen, u_int compat)
        !            37: {
        !            38:        struct sshbuf *b = NULL;
        !            39:        struct sshbuf *sigbuf = NULL;
        !            40:        struct sshbuf *encoded = NULL;
        !            41:        char *ktype = NULL;
        !            42:        const u_char *sigblob;
        !            43:        const u_char *sm;
        !            44:        u_char *m = NULL;
        !            45:        u_char apphash[32];
        !            46:        u_char msghash[32];
        !            47:        u_char sig_flags;
        !            48:        u_int sig_counter;
        !            49:        size_t len;
        !            50:        unsigned long long smlen = 0, mlen = 0;
        !            51:        int r = SSH_ERR_INTERNAL_ERROR;
        !            52:        int ret;
        !            53:
        !            54:        if (key == NULL ||
        !            55:            sshkey_type_plain(key->type) != KEY_ED25519_SK ||
        !            56:            key->ed25519_pk == NULL ||
        !            57:            signature == NULL || signaturelen == 0)
        !            58:                return SSH_ERR_INVALID_ARGUMENT;
        !            59:
        !            60:        if ((b = sshbuf_from(signature, signaturelen)) == NULL)
        !            61:                return SSH_ERR_ALLOC_FAIL;
        !            62:        if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
        !            63:            sshbuf_froms(b, &sigbuf) != 0 ||
        !            64:            sshbuf_get_string_direct(sigbuf, &sigblob, &len) != 0 ||
        !            65:            sshbuf_get_u8(sigbuf, &sig_flags) != 0 ||
        !            66:            sshbuf_get_u32(sigbuf, &sig_counter) != 0) {
        !            67:                r = SSH_ERR_INVALID_FORMAT;
        !            68:                goto out;
        !            69:        }
        !            70:        if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
        !            71:                r = SSH_ERR_KEY_TYPE_MISMATCH;
        !            72:                goto out;
        !            73:        }
        !            74:        if (sshbuf_len(b) != 0) {
        !            75:                r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
        !            76:                goto out;
        !            77:        }
        !            78:        if (len > crypto_sign_ed25519_BYTES) {
        !            79:                r = SSH_ERR_INVALID_FORMAT;
        !            80:                goto out;
        !            81:        }
        !            82:        if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
        !            83:            strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
        !            84:            ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
        !            85:            msghash, sizeof(msghash)) != 0) {
        !            86:                r = SSH_ERR_INVALID_ARGUMENT;
        !            87:                goto out;
        !            88:        }
        !            89:        if ((encoded = sshbuf_new()) == NULL) {
        !            90:                r = SSH_ERR_ALLOC_FAIL;
        !            91:                goto out;
        !            92:        }
        !            93:        if (sshbuf_put(encoded, sigblob, len) != 0 ||
        !            94:            sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
        !            95:            sshbuf_put_u8(encoded, sig_flags) != 0 ||
        !            96:            sshbuf_put_u32(encoded, sig_counter) != 0 ||
        !            97:            sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
        !            98:                r = SSH_ERR_ALLOC_FAIL;
        !            99:                goto out;
        !           100:        }
        !           101:        sm = sshbuf_ptr(encoded);
        !           102:        smlen = sshbuf_len(encoded);
        !           103:        mlen = smlen;
        !           104:        if ((m = malloc(smlen)) == NULL) {
        !           105:                r = SSH_ERR_ALLOC_FAIL;
        !           106:                goto out;
        !           107:        }
        !           108:        if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
        !           109:            key->ed25519_pk)) != 0) {
        !           110:                debug2("%s: crypto_sign_ed25519_open failed: %d",
        !           111:                    __func__, ret);
        !           112:        }
        !           113:        if (ret != 0 || mlen != smlen - len) {
        !           114:                r = SSH_ERR_SIGNATURE_INVALID;
        !           115:                goto out;
        !           116:        }
        !           117:        /* XXX compare 'm' and 'sm + len' ? */
        !           118:        /* success */
        !           119:        r = 0;
        !           120:  out:
        !           121:        if (m != NULL) {
        !           122:                explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */
        !           123:                free(m);
        !           124:        }
        !           125:        sshbuf_free(b);
        !           126:        sshbuf_free(sigbuf);
        !           127:        sshbuf_free(encoded);
        !           128:        free(ktype);
        !           129:        return r;
        !           130: }