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fwknop/lib/cipher_funcs.c
Michael Rash 1d35c33d52 [test suite] added --enable-openssl-checks 
Added --enable-openssl-checks to send all SPA packets encrypted via libfko
through the OpenSSL library to ensure that the libfko usage of AES is always
compatible with OpenSSL.  This ensures that the fwknop usage of AES is properly
implemented as verified by the OpenSSL library, which is a frequently audited
high profile crypto engine.  If a vulnerability is discovered in OpenSSL and a
change is made, then the --enable-openssl-checks mode will allow the test suite
to discover this in a automated fashion for fwknop.
2013-01-25 21:44:24 -05:00

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/*
*****************************************************************************
*
* File: cipher_funcs.c
*
* Author: Damien S. Stuart
*
* Purpose: Cipher functions used by fwknop
*
* Copyright 2009-2010 Damien Stuart (dstuart@dstuart.org)
*
* License (GNU Public License):
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*****************************************************************************
*/
#include <stdio.h>
#include <string.h>
#ifdef WIN32
#include <sys/timeb.h>
#include <time.h>
#include <stdlib.h>
#else
#include <sys/time.h>
#endif
#include "cipher_funcs.h"
#include "digest.h"
#ifndef WIN32
#ifndef RAND_FILE
#define RAND_FILE "/dev/urandom"
#endif
#endif
/* Get random data.
*/
void
get_random_data(unsigned char *data, const size_t len)
{
uint32_t i;
#ifdef WIN32
int rnum;
struct _timeb tb;
_ftime_s(&tb);
srand((uint32_t)(tb.time*1000)+tb.millitm);
for(i=0; i<len; i++)
{
rnum = rand();
*(data+i) = rnum % 0xff;
}
#else
FILE *rfd;
struct timeval tv;
int do_time = 0;
size_t amt_read;
/* Attempt to read seed data from /dev/urandom. If that does not
* work, then fall back to a time-based method (less secure, but
* probably more portable).
*/
if((rfd = fopen(RAND_FILE, "r")) == NULL)
{
do_time = 1;
}
else
{
/* Read seed from /dev/urandom
*/
amt_read = fread(data, len, 1, rfd);
fclose(rfd);
if (amt_read != 1)
do_time = 1;
}
if (do_time)
{
/* Seed based on time (current usecs).
*/
gettimeofday(&tv, NULL);
srand(tv.tv_usec);
for(i=0; i<len; i++)
*(data+i) = rand() % 0xff;
}
#endif
}
/*** These are Rijndael-specific functions ***/
/* Rijndael function to generate initial salt and initialization vector
* (iv). This is is done to be compatible with the data produced via
* the Perl Crypt::CBC module's use of Rijndael.
*/
static void
rij_salt_and_iv(RIJNDAEL_context *ctx, const char *key,
const int key_len, const unsigned char *data, const int legacy_enc_mode)
{
char pw_buf[RIJNDAEL_MAX_KEYSIZE];
unsigned char tmp_buf[MD5_DIGEST_LEN+RIJNDAEL_MAX_KEYSIZE+RIJNDAEL_BLOCKSIZE];
unsigned char kiv_buf[RIJNDAEL_MAX_KEYSIZE+RIJNDAEL_BLOCKSIZE]; /* Key and IV buffer */
unsigned char md5_buf[MD5_DIGEST_LEN]; /* Buffer for computed md5 hash */
int final_key_len = 0;
size_t kiv_len = 0;
if(legacy_enc_mode == 1)
{
/* First make pw 32 bytes (pad with "0" (ascii 0x30)) or truncate.
* Note: pw_buf was initialized with '0' chars (again, not the value
* 0, but the digit '0' character).
*
* This maintains compatibility with the old perl code if absolutely
* necessary in some scenarios, but is not recommended to use since it
* breaks compatibility with how OpenSSL implements AES. This code
* will be removed altogether in a future version of fwknop.
*/
if(key_len < RIJNDAEL_MIN_KEYSIZE)
{
memcpy(pw_buf, key, key_len);
memset(pw_buf+key_len, '0', RIJNDAEL_MIN_KEYSIZE - key_len);
final_key_len = RIJNDAEL_MIN_KEYSIZE;
}
else
{
memcpy(pw_buf, key, key_len);
final_key_len = key_len;
}
}
else
{
memcpy(pw_buf, key, key_len);
final_key_len = key_len;
}
/* If we are decrypting, data will contain the salt. Otherwise,
* for encryption, we generate a random salt.
*/
if(data != NULL)
{
/* Pull the salt from the data
*/
memcpy(ctx->salt, (data+SALT_LEN), SALT_LEN);
}
else
{
/* Generate a random 8-byte salt.
*/
get_random_data(ctx->salt, SALT_LEN);
}
/* Now generate the key and initialization vector.
* (again it is the perl Crypt::CBC way, with a touch of
* fwknop).
*/
memcpy(tmp_buf+MD5_DIGEST_LEN, pw_buf, final_key_len);
memcpy(tmp_buf+MD5_DIGEST_LEN+final_key_len, ctx->salt, SALT_LEN);
while(kiv_len < sizeof(kiv_buf))
{
if(kiv_len == 0)
md5(md5_buf, tmp_buf+MD5_DIGEST_LEN, final_key_len+SALT_LEN);
else
md5(md5_buf, tmp_buf, MD5_DIGEST_LEN+final_key_len+SALT_LEN);
memcpy(tmp_buf, md5_buf, MD5_DIGEST_LEN);
memcpy(kiv_buf + kiv_len, md5_buf, MD5_DIGEST_LEN);
kiv_len += MD5_DIGEST_LEN;
}
memcpy(ctx->key, kiv_buf, RIJNDAEL_MAX_KEYSIZE);
memcpy(ctx->iv, kiv_buf+RIJNDAEL_MAX_KEYSIZE, RIJNDAEL_BLOCKSIZE);
}
/* Initialization entry point.
*/
static void
rijndael_init(RIJNDAEL_context *ctx, const char *key,
const int key_len, const unsigned char *data,
int encryption_mode)
{
/* The default (set in fko.h) is CBC mode
*/
ctx->mode = encryption_mode;
/* Generate the salt and initialization vector.
*/
rij_salt_and_iv(ctx, key, key_len, data, 0);
/* Intialize our Rijndael context.
*/
rijndael_setup(ctx, RIJNDAEL_MAX_KEYSIZE, ctx->key);
}
/* Take a chunk of data, encrypt it in the same way OpenSSL would
* (with a default of AES in CBC mode).
*/
size_t
rij_encrypt(unsigned char *in, size_t in_len,
const char *key, const int key_len,
unsigned char *out, int encryption_mode)
{
RIJNDAEL_context ctx;
int i, pad_val;
unsigned char *ondx = out;
rijndael_init(&ctx, key, key_len, NULL, encryption_mode);
/* Prepend the salt to the ciphertext...
*/
memcpy(ondx, "Salted__", SALT_LEN);
ondx+=SALT_LEN;
memcpy(ondx, ctx.salt, SALT_LEN);
ondx+=SALT_LEN;
/* Add padding to the original plaintext to ensure that it is a
* multiple of the Rijndael block size
*/
pad_val = RIJNDAEL_BLOCKSIZE - (in_len % RIJNDAEL_BLOCKSIZE);
for (i = in_len; i < in_len+pad_val; i++)
in[i] = pad_val;
block_encrypt(&ctx, in, in_len+pad_val, ondx, ctx.iv);
ondx += in_len+pad_val;
return(ondx - out);
}
/* Decrypt the given data.
*/
size_t
rij_decrypt(unsigned char *in, size_t in_len,
const char *key, const int key_len,
unsigned char *out, int encryption_mode)
{
RIJNDAEL_context ctx;
int i, pad_val, pad_err = 0;
unsigned char *pad_s;
unsigned char *ondx = out;
rijndael_init(&ctx, key, key_len, in, encryption_mode);
/* Remove the first block since it contains the salt (it was consumed
* by the rijndael_init() function above).
*/
in_len -= RIJNDAEL_BLOCKSIZE;
memmove(in, in+RIJNDAEL_BLOCKSIZE, in_len);
block_decrypt(&ctx, in, in_len, out, ctx.iv);
ondx += in_len;
/* Find and remove padding.
*/
pad_val = *(ondx-1);
if(pad_val >= 0 && pad_val <= RIJNDAEL_BLOCKSIZE)
{
pad_s = ondx - pad_val;
for(i=0; i < (ondx-pad_s); i++)
{
if(*(pad_s+i) != pad_val)
pad_err++;
}
if(pad_err == 0)
ondx -= pad_val;
}
*ondx = '\0';
return(ondx - out);
}
/* See if we need to add the "Salted__" string to the front of the
* encrypted data.
*/
int
add_salted_str(fko_ctx_t ctx)
{
char *tbuf;
if(strncmp(ctx->encrypted_msg,
B64_RIJNDAEL_SALT, B64_RIJNDAEL_SALT_STR_LEN))
{
/* We need to realloc space for the salt.
*/
tbuf = realloc(ctx->encrypted_msg, ctx->encrypted_msg_len
+ B64_RIJNDAEL_SALT_STR_LEN+1);
if(tbuf == NULL)
return(FKO_ERROR_MEMORY_ALLOCATION);
memmove(tbuf+B64_RIJNDAEL_SALT_STR_LEN, tbuf, ctx->encrypted_msg_len);
ctx->encrypted_msg = memcpy(tbuf,
B64_RIJNDAEL_SALT, B64_RIJNDAEL_SALT_STR_LEN);
/* Adjust the encoded msg len for added SALT value and Make sure we
* are still a properly NULL-terminated string (Ubuntu was one system
* for which this was an issue).
*/
ctx->encrypted_msg_len += B64_RIJNDAEL_SALT_STR_LEN;
tbuf[ctx->encrypted_msg_len] = '\0';
ctx->added_salted_str = 1;
}
return(FKO_SUCCESS);
}
/***EOF***/
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