/****************
* 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 ? xmalloc_secure_clear( sizeof *hd
+ cipher_table[i].contextsize
- sizeof(PROPERLY_ALIGNED_TYPE) )
: xmalloc_clear( sizeof *hd + cipher_table[i].contextsize
- sizeof(PROPERLY_ALIGNED_TYPE) );
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( mode == CIPHER_MODE_AUTO_CFB ) {
if( algo >= 100 )
hd->mode = CIPHER_MODE_CFB;
else
hd->mode = CIPHER_MODE_PHILS_CFB;
}
else
hd->mode = mode;
#ifdef ALLOW_DUMMY
if( algo == CIPHER_ALGO_DUMMY )
hd->mode = CIPHER_MODE_DUMMY;
#endif
return hd;
}
static void
read_pool( byte *buffer, size_t length, int level )
{
int i;
ulong *sp, *dp;
if( length > POOLSIZE ) {
log_bug("too many random bits requested\n");
}
if( !pool_filled ) {
if( read_seed_file() )
pool_filled = 1;
}
/* For level 2 quality (key generation) we alwas make
* sure that the pool has been seeded enough initially */
if( level == 2 && !did_initial_extra_seeding ) {
size_t needed;
pool_balance = 0;
needed = length - pool_balance;
if( needed < POOLSIZE/2 )
needed = POOLSIZE/2;
else if( needed > POOLSIZE )
BUG();
read_random_source( 3, needed, 2 );
pool_balance += needed;
did_initial_extra_seeding=1;
}
/* for level 2 make sure that there is enough random in the pool */
if( level == 2 && pool_balance < length ) {
size_t needed;
if( pool_balance < 0 )
pool_balance = 0;
needed = length - pool_balance;
if( needed > POOLSIZE )
BUG();
read_random_source( 3, needed, 2 );
pool_balance += needed;
}
/* make sure the pool is filled */
while( !pool_filled )
random_poll();
/* do always a fast random poll */
fast_random_poll();
if( !level ) { /* no need for cryptographic strong random */
/* create a new pool */
for(i=0,dp=(ulong*)keypool, sp=(ulong*)rndpool;
i < POOLWORDS; i++, dp++, sp++ )
*dp = *sp + ADD_VALUE;
/* must mix both pools */
mix_pool(rndpool); rndstats.mixrnd++;
mix_pool(keypool); rndstats.mixkey++;
memcpy( buffer, keypool, length );
}
else {
/* mix the pool (if add_randomness() didn't it) */
if( !just_mixed ) {
mix_pool(rndpool);
rndstats.mixrnd++;
}
/* create a new pool */
for(i=0,dp=(ulong*)keypool, sp=(ulong*)rndpool;
i < POOLWORDS; i++, dp++, sp++ )
*dp = *sp + ADD_VALUE;
/* and mix both pools */
mix_pool(rndpool); rndstats.mixrnd++;
mix_pool(keypool); rndstats.mixkey++;
/* read the required data
* we use a readpoiter to read from a different postion each
* time */
while( length-- ) {
*buffer++ = keypool[pool_readpos++];
if( pool_readpos >= POOLSIZE )
pool_readpos = 0;
pool_balance--;
}
if( pool_balance < 0 )
pool_balance = 0;
/* and clear the keypool */
memset( keypool, 0, POOLSIZE );
}
}
