/**
* Just compute Yc = g^a % p and return it in "key_exchange_message". The
* premaster secret is Ys ^ a % p.
*/
int dh_key_exchange( dh_key *server_dh_key,
unsigned char *premaster_secret,
unsigned char **key_exchange_message )
{
huge Yc;
huge Z;
huge a;
int message_size;
short transmit_len;
// TODO obviously, make this random, and much longer
set_huge( &a, 6 );
mod_pow( &server_dh_key->g, &a, &server_dh_key->p, &Yc );
mod_pow( &server_dh_key->Y, &a, &server_dh_key->p, &Z );
// Now copy Z into premaster secret and Yc into key_exchange_message
memcpy( premaster_secret, Z.rep, Z.size );
message_size = Yc.size + 2;
transmit_len = htons( Yc.size );
*key_exchange_message = malloc( message_size );
memcpy( *key_exchange_message, &transmit_len, 2 );
memcpy( *key_exchange_message + 2, Yc.rep, Yc.size );
free_huge( &Yc );
free_huge( &Z );
free_huge( &a );
return message_size;
}
void subtract( huge *h1, huge *h2 )
{
int result_sign;
// First compute sign of result, then compute magnitude
if ( compare( h1, h2 ) > 0 )
{
result_sign = h1->sign;
if ( h1->sign == h2->sign )
{
subtract_magnitude( h1, h2 );
}
else
{
add_magnitude( h1, h2 );
}
}
else
{
huge tmp;
// put h1 into tmp and h2 into h1 to swap the operands
set_huge( &tmp, 0 ); // initialize
copy_huge( &tmp, h1 );
copy_huge( h1, h2 );
if ( h1->sign == tmp.sign )
{
result_sign = !( h1->sign );
subtract_magnitude( h1, &tmp );
}
else
{
result_sign = !( h2->sign );
add_magnitude( h1, &tmp );
}
free_huge( &tmp );
}
// Use the stored sign to set the result
h1->sign = result_sign;
}
void APCObject::Delete(APCHandle* handle) {
auto const obj = fromHandle(handle);
obj->~APCObject();
// No need to run Prop destructors.
free_huge(obj);
}
