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Code Issues Releases Wiki Activity

encryption key creation is pretty expensive -- defer creating it until we're sure we actually need it for that peer.

This commit is contained in:
Charles Kerr 2007-10-11 02:22:17 +00:00
parent 23d2f77778
commit ead1ff5b72
1 changed files with 30 additions and 20 deletions
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50
libtransmission/crypto.c
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@ -88,6 +88,29 @@ struct tr_crypto
};
static void
ensureKeyExists( tr_crypto * crypto )
{
if( crypto->dh == NULL )
{
int len, offset;
crypto->dh = DH_new( );
crypto->dh->p = BN_bin2bn( dh_P, sizeof(dh_P), NULL );
crypto->dh->g = BN_bin2bn( dh_G, sizeof(dh_G), NULL );
DH_generate_key( crypto->dh );
/* DH can generate key sizes that are smaller than the size of
P with exponentially decreasing probability, in which case
the msb's of myPublicKey need to be zeroed appropriately. */
len = DH_size( crypto->dh );
offset = KEY_LEN - len;
assert( len <= KEY_LEN );
memset( crypto->myPublicKey, 0, offset );
BN_bn2bin( crypto->dh->pub_key, crypto->myPublicKey + offset );
}
}
/**
***
**/
@ -96,27 +119,12 @@ tr_crypto *
tr_cryptoNew( const uint8_t * torrentHash,
int isIncoming )
{
int len, offset;
tr_crypto * crypto;
crypto = tr_new0( tr_crypto, 1 );
crypto->isIncoming = isIncoming ? 1 : 0;
crypto->dh = NULL;
tr_cryptoSetTorrentHash( crypto, torrentHash );
crypto->dh = DH_new( );
crypto->dh->p = BN_bin2bn( dh_P, sizeof(dh_P), NULL );
crypto->dh->g = BN_bin2bn( dh_G, sizeof(dh_G), NULL );
DH_generate_key( crypto->dh );
/* DH can generate key sizes that are smaller than the size of
P with exponentially decreasing probability, in which case
the msb's of myPublicKey need to be zeroed appropriately. */
len = DH_size( crypto->dh );
offset = KEY_LEN - len;
assert( len <= KEY_LEN );
memset( crypto->myPublicKey, 0, offset );
BN_bn2bin( crypto->dh->pub_key, crypto->myPublicKey + offset );
return crypto;
}
@ -124,9 +132,8 @@ void
tr_cryptoFree( tr_crypto * crypto )
{
assert( crypto != NULL );
assert( crypto->dh != NULL );
DH_free( crypto->dh );
if( crypto->dh != NULL )
DH_free( crypto->dh );
tr_free( crypto );
}
@ -141,7 +148,9 @@ tr_cryptoComputeSecret( tr_crypto * crypto,
int len, offset;
uint8_t secret[KEY_LEN];
BIGNUM * bn = BN_bin2bn( peerPublicKey, KEY_LEN, NULL );
assert( DH_size(crypto->dh) == KEY_LEN );
ensureKeyExists( crypto );
assert( DH_size( crypto->dh ) == KEY_LEN );
len = DH_compute_key( secret, bn, crypto->dh );
assert( len <= KEY_LEN );
@ -158,6 +167,7 @@ tr_cryptoComputeSecret( tr_crypto * crypto,
const uint8_t*
tr_cryptoGetMyPublicKey( const tr_crypto * crypto, int * setme_len )
{
ensureKeyExists( (tr_crypto*) crypto );
*setme_len = KEY_LEN;
return crypto->myPublicKey;
}