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gnupg/cipher/cipher.c
Werner Koch 5ae562b41d edit-key is now complete
1998-07-29 19:35:05 +00:00

563 lines
14 KiB
C
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/* cipher.c - cipher dispatcher
* Copyright (C) 1998 Free Software Foundation, Inc.
*
* This file is part of GNUPG.
*
* GNUPG 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.
*
* GNUPG 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
*/
#define DEFINES_CIPHER_HANDLE 1
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include "util.h"
#include "errors.h"
#include "cipher.h"
#include "blowfish.h"
#include "cast5.h"
#include "dynload.h"
#define MAX_BLOCKSIZE 16
#define TABLE_SIZE 10
struct cipher_table_s {
const char *name;
int algo;
size_t blocksize;
size_t keylen;
size_t contextsize; /* allocate this amount of context */
void (*setkey)( void *c, byte *key, unsigned keylen );
void (*encrypt)( void *c, byte *outbuf, byte *inbuf );
void (*decrypt)( void *c, byte *outbuf, byte *inbuf );
};
static struct cipher_table_s cipher_table[TABLE_SIZE];
struct cipher_handle_s {
int algo;
int mode;
size_t blocksize;
byte iv[MAX_BLOCKSIZE]; /* (this should be ulong aligned) */
byte lastiv[MAX_BLOCKSIZE];
int unused; /* in IV */
void (*setkey)( void *c, byte *key, unsigned keylen );
void (*encrypt)( void *c, byte *outbuf, byte *inbuf );
void (*decrypt)( void *c, byte *outbuf, byte *inbuf );
byte context[1];
};
static void
dummy_setkey( void *c, byte *key, unsigned keylen ) { }
static void
dummy_encrypt_block( void *c, byte *outbuf, byte *inbuf ) { BUG(); }
static void
dummy_decrypt_block( void *c, byte *outbuf, byte *inbuf ) { BUG(); }
/****************
* Put the static entries into the table.
*/
static void
setup_cipher_table()
{
int i;
i = 0;
cipher_table[i].algo = CIPHER_ALGO_BLOWFISH;
cipher_table[i].name = blowfish_get_info( cipher_table[i].algo,
&cipher_table[i].keylen,
&cipher_table[i].blocksize,
&cipher_table[i].contextsize,
&cipher_table[i].setkey,
&cipher_table[i].encrypt,
&cipher_table[i].decrypt );
if( !cipher_table[i].name )
BUG();
i++;
cipher_table[i].algo = CIPHER_ALGO_CAST5;
cipher_table[i].name = cast5_get_info( cipher_table[i].algo,
&cipher_table[i].keylen,
&cipher_table[i].blocksize,
&cipher_table[i].contextsize,
&cipher_table[i].setkey,
&cipher_table[i].encrypt,
&cipher_table[i].decrypt );
if( !cipher_table[i].name )
BUG();
i++;
cipher_table[i].algo = CIPHER_ALGO_BLOWFISH160;
cipher_table[i].name = blowfish_get_info( cipher_table[i].algo,
&cipher_table[i].keylen,
&cipher_table[i].blocksize,
&cipher_table[i].contextsize,
&cipher_table[i].setkey,
&cipher_table[i].encrypt,
&cipher_table[i].decrypt );
if( !cipher_table[i].name )
BUG();
i++;
cipher_table[i].algo = CIPHER_ALGO_DUMMY;
cipher_table[i].name = "DUMMY";
cipher_table[i].blocksize = 8;
cipher_table[i].keylen = 128;
cipher_table[i].contextsize = 0;
cipher_table[i].setkey = dummy_setkey;
cipher_table[i].encrypt = dummy_encrypt_block;
cipher_table[i].decrypt = dummy_decrypt_block;
i++;
for( ; i < TABLE_SIZE; i++ )
cipher_table[i].name = NULL;
}
/****************
* Try to load all modules and return true if new modules are available
*/
static int
load_cipher_modules()
{
static int done = 0;
static int initialized = 0;
void *context = NULL;
struct cipher_table_s *ct;
int ct_idx;
int i;
const char *name;
int any = 0;
if( !initialized ) {
setup_cipher_table(); /* load static modules on the first call */
initialized = 1;
return 1;
}
if( done )
return 0;
done = 1;
for(ct_idx=0, ct = cipher_table; ct_idx < TABLE_SIZE; ct_idx++,ct++ ) {
if( !ct->name )
break;
}
if( ct_idx >= TABLE_SIZE-1 )
BUG(); /* table already full */
/* now load all extensions */
while( (name = enum_gnupgext_ciphers( &context, &ct->algo,
&ct->keylen, &ct->blocksize, &ct->contextsize,
&ct->setkey, &ct->encrypt, &ct->decrypt)) ) {
if( ct->blocksize != 8 && ct->blocksize != 16 ) {
log_info("skipping cipher %d: unsupported blocksize\n", ct->algo);
continue;
}
for(i=0; cipher_table[i].name; i++ )
if( cipher_table[i].algo == ct->algo )
break;
if( cipher_table[i].name ) {
log_info("skipping cipher %d: already loaded\n", ct->algo );
continue;
}
/* put it into the table */
if( g10_opt_verbose > 1 )
log_info("loaded cipher %d (%s)\n", ct->algo, name);
ct->name = name;
ct_idx++;
ct++;
any = 1;
/* check whether there are more available table slots */
if( ct_idx >= TABLE_SIZE-1 ) {
log_info("cipher table full; ignoring other extensions\n");
break;
}
}
enum_gnupgext_ciphers( &context, NULL, NULL, NULL, NULL,
NULL, NULL, NULL );
return any;
}
/****************
* Map a string to the cipher algo
*/
int
string_to_cipher_algo( const char *string )
{
int i;
const char *s;
do {
for(i=0; (s=cipher_table[i].name); i++ )
if( !stricmp( s, string ) )
return cipher_table[i].algo;
} while( load_cipher_modules() );
return 0;
}
/****************
* Map a cipher algo to a string
*/
const char *
cipher_algo_to_string( int algo )
{
int i;
do {
for(i=0; cipher_table[i].name; i++ )
if( cipher_table[i].algo == algo )
return cipher_table[i].name;
} while( load_cipher_modules() );
return NULL;
}
/****************
* Return 0 if the cipher algo is available
*/
int
check_cipher_algo( int algo )
{
int i;
do {
for(i=0; cipher_table[i].name; i++ )
if( cipher_table[i].algo == algo )
return 0; /* okay */
} while( load_cipher_modules() );
return G10ERR_CIPHER_ALGO;
}
unsigned
cipher_get_keylen( int algo )
{
int i;
unsigned len = 0;
do {
for(i=0; cipher_table[i].name; i++ ) {
if( cipher_table[i].algo == algo ) {
len = cipher_table[i].keylen;
if( !len )
log_bug("cipher %d w/o key length\n", algo );
return len;
}
}
} while( load_cipher_modules() );
log_bug("cipher %d not found\n", algo );
return 0;
}
unsigned
cipher_get_blocksize( int algo )
{
int i;
unsigned len = 0;
do {
for(i=0; cipher_table[i].name; i++ ) {
if( cipher_table[i].algo == algo ) {
len = cipher_table[i].blocksize;
if( !len )
log_bug("cipher %d w/o blocksize\n", algo );
return len;
}
}
} while( load_cipher_modules() );
log_bug("cipher %d not found\n", algo );
return 0;
}
/****************
* Open a cipher handle for use with algorithm ALGO, in mode MODE
* and put it into secure memory if SECURE is true.
*/
CIPHER_HANDLE
cipher_open( int algo, int mode, int secure )
{
CIPHER_HANDLE hd;
int i;
fast_random_poll();
do {
for(i=0; cipher_table[i].name; i++ )
if( cipher_table[i].algo == algo )
break;
} while( !cipher_table[i].name && load_cipher_modules() );
if( !cipher_table[i].name ) {
log_fatal("cipher_open: algorithm %d not available\n", algo );
return NULL;
}
/* ? perform selftest here and mark this with a flag in cipher_table ? */
hd = secure ? m_alloc_secure_clear( sizeof *hd
+ cipher_table[i].contextsize )
: m_alloc_clear( sizeof *hd + cipher_table[i].contextsize );
hd->algo = algo;
hd->blocksize = cipher_table[i].blocksize;
hd->setkey = cipher_table[i].setkey;
hd->encrypt = cipher_table[i].encrypt;
hd->decrypt = cipher_table[i].decrypt;
if( algo == CIPHER_ALGO_DUMMY )
hd->mode = CIPHER_MODE_DUMMY;
else if( mode == CIPHER_MODE_AUTO_CFB ) {
if( algo == CIPHER_ALGO_BLOWFISH160 || algo >= 100 )
hd->mode = CIPHER_MODE_CFB;
else
hd->mode = CIPHER_MODE_PHILS_CFB;
}
else
hd->mode = mode;
return hd;
}
void
cipher_close( CIPHER_HANDLE c )
{
m_free(c);
}
void
cipher_setkey( CIPHER_HANDLE c, byte *key, unsigned keylen )
{
(*c->setkey)( &c->context, key, keylen );
}
void
cipher_setiv( CIPHER_HANDLE c, const byte *iv )
{
if( iv )
memcpy( c->iv, iv, c->blocksize );
else
memset( c->iv, 0, c->blocksize );
c->unused = 0;
}
static void
do_ecb_encrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nblocks )
{
unsigned n;
for(n=0; n < nblocks; n++ ) {
(*c->encrypt)( &c->context, outbuf, inbuf );
inbuf += c->blocksize;
outbuf += c->blocksize;
}
}
static void
do_ecb_decrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nblocks )
{
unsigned n;
for(n=0; n < nblocks; n++ ) {
(*c->decrypt)( &c->context, outbuf, inbuf );
inbuf += c->blocksize;
outbuf += c->blocksize;
}
}
static void
do_cfb_encrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nbytes )
{
byte *ivp;
size_t blocksize = c->blocksize;
if( nbytes <= c->unused ) {
/* short enough to be encoded by the remaining XOR mask */
/* XOR the input with the IV and store input into IV */
for(ivp=c->iv+c->blocksize - c->unused; nbytes; nbytes--, c->unused-- )
*outbuf++ = (*ivp++ ^= *inbuf++);
return;
}
if( c->unused ) {
/* XOR the input with the IV and store input into IV */
nbytes -= c->unused;
for(ivp=c->iv+blocksize - c->unused; c->unused; c->unused-- )
*outbuf++ = (*ivp++ ^= *inbuf++);
}
/* now we can process complete blocks */
while( nbytes >= blocksize ) {
int i;
/* encrypt the IV (and save the current one) */
memcpy( c->lastiv, c->iv, blocksize );
(*c->encrypt)( &c->context, c->iv, c->iv );
/* XOR the input with the IV and store input into IV */
for(ivp=c->iv,i=0; i < blocksize; i++ )
*outbuf++ = (*ivp++ ^= *inbuf++);
nbytes -= blocksize;
}
if( nbytes ) { /* process the remaining bytes */
/* encrypt the IV (and save the current one) */
memcpy( c->lastiv, c->iv, blocksize );
(*c->encrypt)( &c->context, c->iv, c->iv );
c->unused = blocksize;
/* and apply the xor */
c->unused -= nbytes;
for(ivp=c->iv; nbytes; nbytes-- )
*outbuf++ = (*ivp++ ^= *inbuf++);
}
}
static void
do_cfb_decrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nbytes )
{
byte *ivp;
ulong temp;
size_t blocksize = c->blocksize;
if( nbytes <= c->unused ) {
/* short enough to be encoded by the remaining XOR mask */
/* XOR the input with the IV and store input into IV */
for(ivp=c->iv+blocksize - c->unused; nbytes; nbytes--,c->unused--){
temp = *inbuf++;
*outbuf++ = *ivp ^ temp;
*ivp++ = temp;
}
return;
}
if( c->unused ) {
/* XOR the input with the IV and store input into IV */
nbytes -= c->unused;
for(ivp=c->iv+blocksize - c->unused; c->unused; c->unused-- ) {
temp = *inbuf++;
*outbuf++ = *ivp ^ temp;
*ivp++ = temp;
}
}
/* now we can process complete blocks */
while( nbytes >= blocksize ) {
int i;
/* encrypt the IV (and save the current one) */
memcpy( c->lastiv, c->iv, blocksize );
(*c->encrypt)( &c->context, c->iv, c->iv );
/* XOR the input with the IV and store input into IV */
for(ivp=c->iv,i=0; i < blocksize; i++ ) {
temp = *inbuf++;
*outbuf++ = *ivp ^ temp;
*ivp++ = temp;
}
nbytes -= blocksize;
}
if( nbytes ) { /* process the remaining bytes */
/* encrypt the IV (and save the current one) */
memcpy( c->lastiv, c->iv, blocksize );
(*c->encrypt)( &c->context, c->iv, c->iv );
c->unused = blocksize;
/* and apply the xor */
c->unused -= nbytes;
for(ivp=c->iv; nbytes; nbytes-- ) {
temp = *inbuf++;
*outbuf++ = *ivp ^ temp;
*ivp++ = temp;
}
}
}
/****************
* Encrypt INBUF to OUTBUF with the mode selected at open.
* inbuf and outbuf may overlap or be the same.
* Depending on the mode some some contraints apply to NBYTES.
*/
void
cipher_encrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nbytes )
{
switch( c->mode ) {
case CIPHER_MODE_ECB:
assert(!(nbytes%8));
do_ecb_encrypt(c, outbuf, inbuf, nbytes/8 );
break;
case CIPHER_MODE_CFB:
case CIPHER_MODE_PHILS_CFB:
do_cfb_encrypt(c, outbuf, inbuf, nbytes );
break;
case CIPHER_MODE_DUMMY:
if( inbuf != outbuf )
memmove( outbuf, inbuf, nbytes );
break;
default: log_fatal("cipher_encrypt: invalid mode %d\n", c->mode );
}
}
/****************
* Decrypt INBUF to OUTBUF with the mode selected at open.
* inbuf and outbuf may overlap or be the same.
* Depending on the mode some some contraints apply to NBYTES.
*/
void
cipher_decrypt( CIPHER_HANDLE c, byte *outbuf, byte *inbuf, unsigned nbytes )
{
switch( c->mode ) {
case CIPHER_MODE_ECB:
assert(!(nbytes%8));
do_ecb_decrypt(c, outbuf, inbuf, nbytes/8 );
break;
case CIPHER_MODE_CFB:
case CIPHER_MODE_PHILS_CFB:
do_cfb_decrypt(c, outbuf, inbuf, nbytes );
break;
case CIPHER_MODE_DUMMY:
if( inbuf != outbuf )
memmove( outbuf, inbuf, nbytes );
break;
default: log_fatal("cipher_decrypt: invalid mode %d\n", c->mode );
}
}
/****************
* Used for PGP's somewhat strange CFB mode. Only works if
* the handle is in PHILS_CFB mode
*/
void
cipher_sync( CIPHER_HANDLE c )
{
if( c->mode == CIPHER_MODE_PHILS_CFB && c->unused ) {
memmove(c->iv + c->unused, c->iv, c->blocksize - c->unused );
memcpy(c->iv, c->lastiv + c->blocksize - c->unused, c->unused);
c->unused = 0;
}
}
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