Annotation of src/usr.bin/ssh/kexc25519.c, Revision 1.8
1.8 ! markus 1: /* $OpenBSD: kexc25519.c,v 1.7 2014/05/02 03:27:54 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2001, 2013 Markus Friedl. All rights reserved.
4: * Copyright (c) 2010 Damien Miller. All rights reserved.
5: * Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: *
16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26: */
27:
28: #include <sys/types.h>
29:
30: #include <signal.h>
31: #include <string.h>
32:
33: #include <openssl/bn.h>
34: #include <openssl/evp.h>
35:
1.8 ! markus 36: #include "sshbuf.h"
1.1 markus 37: #include "ssh2.h"
1.8 ! markus 38: #include "sshkey.h"
1.1 markus 39: #include "cipher.h"
40: #include "kex.h"
41: #include "log.h"
1.3 djm 42: #include "digest.h"
1.8 ! markus 43: #include "ssherr.h"
1.1 markus 44:
45: extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE],
46: const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE])
1.7 djm 47: __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
48: __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)))
49: __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE)));
1.1 markus 50:
51: void
52: kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
53: {
54: static const u_char basepoint[CURVE25519_SIZE] = {9};
55:
56: arc4random_buf(key, CURVE25519_SIZE);
57: crypto_scalarmult_curve25519(pub, key, basepoint);
58: }
59:
1.8 ! markus 60: int
1.1 markus 61: kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
1.8 ! markus 62: const u_char pub[CURVE25519_SIZE], struct sshbuf *out)
1.1 markus 63: {
64: u_char shared_key[CURVE25519_SIZE];
1.8 ! markus 65: int r;
1.1 markus 66:
67: crypto_scalarmult_curve25519(shared_key, key, pub);
68: #ifdef DEBUG_KEXECDH
69: dump_digest("shared secret", shared_key, CURVE25519_SIZE);
70: #endif
1.8 ! markus 71: sshbuf_reset(out);
! 72: r = sshbuf_put_bignum2_bytes(out, shared_key, CURVE25519_SIZE);
1.5 tedu 73: explicit_bzero(shared_key, CURVE25519_SIZE);
1.8 ! markus 74: return r;
1.1 markus 75: }
76:
1.8 ! markus 77: int
1.1 markus 78: kex_c25519_hash(
1.3 djm 79: int hash_alg,
1.8 ! markus 80: const char *client_version_string,
! 81: const char *server_version_string,
! 82: const char *ckexinit, size_t ckexinitlen,
! 83: const char *skexinit, size_t skexinitlen,
! 84: const u_char *serverhostkeyblob, size_t sbloblen,
1.1 markus 85: const u_char client_dh_pub[CURVE25519_SIZE],
86: const u_char server_dh_pub[CURVE25519_SIZE],
1.8 ! markus 87: const u_char *shared_secret, size_t secretlen,
! 88: u_char *hash, size_t *hashlen)
1.1 markus 89: {
1.8 ! markus 90: struct sshbuf *b;
! 91: int r;
1.1 markus 92:
1.8 ! markus 93: if (*hashlen < ssh_digest_bytes(hash_alg))
! 94: return SSH_ERR_INVALID_ARGUMENT;
! 95: if ((b = sshbuf_new()) == NULL)
! 96: return SSH_ERR_ALLOC_FAIL;
! 97: if ((r = sshbuf_put_cstring(b, client_version_string)) < 0 ||
! 98: (r = sshbuf_put_cstring(b, server_version_string)) < 0 ||
! 99: /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
! 100: (r = sshbuf_put_u32(b, ckexinitlen+1)) < 0 ||
! 101: (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) < 0 ||
! 102: (r = sshbuf_put(b, ckexinit, ckexinitlen)) < 0 ||
! 103: (r = sshbuf_put_u32(b, skexinitlen+1)) < 0 ||
! 104: (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) < 0 ||
! 105: (r = sshbuf_put(b, skexinit, skexinitlen)) < 0 ||
! 106: (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) < 0 ||
! 107: (r = sshbuf_put_string(b, client_dh_pub, CURVE25519_SIZE)) < 0 ||
! 108: (r = sshbuf_put_string(b, server_dh_pub, CURVE25519_SIZE)) < 0 ||
! 109: (r = sshbuf_put(b, shared_secret, secretlen)) < 0) {
! 110: sshbuf_free(b);
! 111: return r;
! 112: }
1.1 markus 113: #ifdef DEBUG_KEX
1.8 ! markus 114: sshbuf_dump(b, stderr);
1.1 markus 115: #endif
1.8 ! markus 116: if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
! 117: sshbuf_free(b);
! 118: return SSH_ERR_LIBCRYPTO_ERROR;
! 119: }
! 120: sshbuf_free(b);
! 121: *hashlen = ssh_digest_bytes(hash_alg);
1.1 markus 122: #ifdef DEBUG_KEX
1.8 ! markus 123: dump_digest("hash", hash, *hashlen);
1.1 markus 124: #endif
1.8 ! markus 125: return 0;
1.1 markus 126: }
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