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Diffstat (limited to 'crypto/openssh/kexc25519.c')
-rw-r--r-- | crypto/openssh/kexc25519.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/crypto/openssh/kexc25519.c b/crypto/openssh/kexc25519.c new file mode 100644 index 0000000..48ca4aa --- /dev/null +++ b/crypto/openssh/kexc25519.c @@ -0,0 +1,122 @@ +/* $OpenBSD: kexc25519.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */ +/* + * Copyright (c) 2001, 2013 Markus Friedl. All rights reserved. + * Copyright (c) 2010 Damien Miller. All rights reserved. + * Copyright (c) 2013 Aris Adamantiadis. 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" + +#include <sys/types.h> + +#include <signal.h> +#include <string.h> + +#include <openssl/bn.h> +#include <openssl/evp.h> + +#include "buffer.h" +#include "ssh2.h" +#include "key.h" +#include "cipher.h" +#include "kex.h" +#include "log.h" +#include "digest.h" + +extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE], + const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE]) + __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) + __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))) + __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE))); + +void +kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) +{ + static const u_char basepoint[CURVE25519_SIZE] = {9}; + + arc4random_buf(key, CURVE25519_SIZE); + crypto_scalarmult_curve25519(pub, key, basepoint); +} + +void +kexc25519_shared_key(const u_char key[CURVE25519_SIZE], + const u_char pub[CURVE25519_SIZE], Buffer *out) +{ + u_char shared_key[CURVE25519_SIZE]; + + crypto_scalarmult_curve25519(shared_key, key, pub); +#ifdef DEBUG_KEXECDH + dump_digest("shared secret", shared_key, CURVE25519_SIZE); +#endif + buffer_clear(out); + buffer_put_bignum2_from_string(out, shared_key, CURVE25519_SIZE); + memset(shared_key, 0, CURVE25519_SIZE); /* XXX explicit_bzero() */ +} + +void +kex_c25519_hash( + int hash_alg, + char *client_version_string, + char *server_version_string, + char *ckexinit, int ckexinitlen, + char *skexinit, int skexinitlen, + u_char *serverhostkeyblob, int sbloblen, + const u_char client_dh_pub[CURVE25519_SIZE], + const u_char server_dh_pub[CURVE25519_SIZE], + const u_char *shared_secret, u_int secretlen, + u_char **hash, u_int *hashlen) +{ + Buffer b; + static u_char digest[SSH_DIGEST_MAX_LENGTH]; + + buffer_init(&b); + buffer_put_cstring(&b, client_version_string); + buffer_put_cstring(&b, server_version_string); + + /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ + buffer_put_int(&b, ckexinitlen+1); + buffer_put_char(&b, SSH2_MSG_KEXINIT); + buffer_append(&b, ckexinit, ckexinitlen); + buffer_put_int(&b, skexinitlen+1); + buffer_put_char(&b, SSH2_MSG_KEXINIT); + buffer_append(&b, skexinit, skexinitlen); + + buffer_put_string(&b, serverhostkeyblob, sbloblen); + buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE); + buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE); + buffer_append(&b, shared_secret, secretlen); + +#ifdef DEBUG_KEX + buffer_dump(&b); +#endif + if (ssh_digest_buffer(hash_alg, &b, digest, sizeof(digest)) != 0) + fatal("%s: digest_buffer failed", __func__); + + buffer_free(&b); + +#ifdef DEBUG_KEX + dump_digest("hash", digest, ssh_digest_bytes(hash_alg)); +#endif + *hash = digest; + *hashlen = ssh_digest_bytes(hash_alg); +} |