function check_ElGPlainMult_correctness($pk, $sk)
{
$group = $pk["group"];
foreach ($group["G"] as $m) {
foreach ($group["G"] as $plain) {
if (_DEBUG >= 8) {
echo "Checking ElGamal plain mult for {$m} and {$plain}...";
}
$c = ElG_Enc($m, $pk);
$cmult = ElG_PlainMult($c, $plain, $pk);
if (modular_mult($m, $plain, $group["modulo"]) != ElG_Dec($cmult, $pk, $sk)) {
if (_DEBUG >= 1) {
echo "\nERROR : ElGamal homomorphic plain multiplication error for m = {$m} and plain = {$plain}\n";
}
return false;
}
if (_DEBUG >= 8) {
echo "\n";
}
}
}
return true;
}
$b = $group["G"][array_rand($group["G"])];
$begin_time = microtime(true);
$ca = ElG_Enc($a, $pk);
$end_time = microtime(true);
$cumul["enc"] += 1000 * ($end_time - $begin_time);
$begin_time = microtime(true);
ElG_Dec($ca, $pk, $sk);
$end_time = microtime(true);
$cumul["dec"] += 1000 * ($end_time - $begin_time);
$cb = ElG_Enc($b, $pk);
$begin_time = microtime(true);
ElG_Mult($ca, $cb, $pk);
$end_time = microtime(true);
$cumul["mult"] += 1000 * ($end_time - $begin_time);
$begin_time = microtime(true);
ElG_PlainMult($ca, $b, $pk);
$end_time = microtime(true);
$cumul["plainmult"] += 1000 * ($end_time - $begin_time);
$begin_time = microtime(true);
ElG_ScalarExp($ca, $b, $pk);
$end_time = microtime(true);
$cumul["scexp"] += 1000 * ($end_time - $begin_time);
$begin_time = microtime(true);
ElG_Rerand($ca, $pk);
$end_time = microtime(true);
$cumul["rerand"] += 1000 * ($end_time - $begin_time);
}
echo "For {$limit} tests and a security of {$lambda} bits, mean ElGamal running times are:\n";
echo "\tKeyGen: ", $cumul["keygen"] / $limit, "ms\n";
echo "\tEnc: ", $cumul["enc"] / $limit, "ms\n";
echo "\tDec: ", $cumul["dec"] / $limit, "ms\n";
