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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file Data Channel Cryptography OpenSSL-specific backend interface
*/
#include "syshead.h"
#include "basic.h"
#include "buffer.h"
#include "integer.h"
#include "crypto_backend.h"
#include <openssl/objects.h>
#include <openssl/evp.h>
#include <openssl/des.h>
/*
* Check for key size creepage.
*/
#if MAX_CIPHER_KEY_LENGTH < EVP_MAX_KEY_LENGTH
#warning Some OpenSSL EVP ciphers now support key lengths greater than MAX_CIPHER_KEY_LENGTH -- consider increasing MAX_CIPHER_KEY_LENGTH
#endif
#if MAX_HMAC_KEY_LENGTH < EVP_MAX_MD_SIZE
#warning Some OpenSSL HMAC message digests now support key lengths greater than MAX_HMAC_KEY_LENGTH -- consider increasing MAX_HMAC_KEY_LENGTH
#endif
/*
*
* Workarounds for incompatibilites between OpenSSL libraries.
* Right now we accept OpenSSL libraries from 0.9.5 to 0.9.7.
*
*/
#if SSLEAY_VERSION_NUMBER < 0x00907000L
#endif
#if SSLEAY_VERSION_NUMBER < 0x00906000
static inline bool
cipher_ok (const char* name)
{
const int i = strlen (name) - 4;
if (i >= 0)
return !strcmp (name + i, "-CBC");
else
return false;
}
#else
static inline bool
cipher_ok (const char* name)
{
return true;
}
#endif
#if SSLEAY_VERSION_NUMBER < 0x0090581f
#endif
void
show_available_ciphers ()
{
int nid;
#ifndef ENABLE_SMALL
printf ("The following ciphers and cipher modes are available\n"
"for use with " PACKAGE_NAME ". Each cipher shown below may be\n"
"used as a parameter to the --cipher option. The default\n"
"key size is shown as well as whether or not it can be\n"
"changed with the --keysize directive. Using a CBC mode\n"
"is recommended.\n\n");
#endif
for (nid = 0; nid < 10000; ++nid) /* is there a better way to get the size of the nid list? */
{
const EVP_CIPHER *cipher = EVP_get_cipherbynid (nid);
if (cipher && cipher_ok (OBJ_nid2sn (nid)))
{
const unsigned int mode = EVP_CIPHER_mode (cipher);
if (mode == EVP_CIPH_CBC_MODE
#ifdef ALLOW_NON_CBC_CIPHERS
|| mode == EVP_CIPH_CFB_MODE || mode == EVP_CIPH_OFB_MODE
#endif
)
printf ("%s %d bit default key (%s)\n",
OBJ_nid2sn (nid),
EVP_CIPHER_key_length (cipher) * 8,
((EVP_CIPHER_flags (cipher) & EVP_CIPH_VARIABLE_LENGTH) ?
"variable" : "fixed"));
}
}
printf ("\n");
}
void
show_available_digests ()
{
int nid;
#ifndef ENABLE_SMALL
printf ("The following message digests are available for use with\n"
PACKAGE_NAME ". A message digest is used in conjunction with\n"
"the HMAC function, to authenticate received packets.\n"
"You can specify a message digest as parameter to\n"
"the --auth option.\n\n");
#endif
for (nid = 0; nid < 10000; ++nid)
{
const EVP_MD *digest = EVP_get_digestbynid (nid);
if (digest)
{
printf ("%s %d bit digest size\n",
OBJ_nid2sn (nid), EVP_MD_size (digest) * 8);
}
}
printf ("\n");
}
void
show_available_engines ()
{
#if CRYPTO_ENGINE /* Only defined for OpenSSL */
ENGINE *e;
printf ("OpenSSL Crypto Engines\n\n");
ENGINE_load_builtin_engines ();
e = ENGINE_get_first ();
while (e)
{
printf ("%s [%s]\n",
ENGINE_get_name (e),
ENGINE_get_id (e));
e = ENGINE_get_next (e);
}
ENGINE_cleanup ();
#else
printf ("Sorry, OpenSSL hardware crypto engine functionality is not available.\n");
#endif
}
/*
*
* Random number functions, used in cases where we want
* reasonably strong cryptographic random number generation
* without depleting our entropy pool. Used for random
* IV values and a number of other miscellaneous tasks.
*
*/
int rand_bytes(uint8_t *output, int len)
{
return RAND_bytes (output, len);
}
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