function check_ElGScalarExp_correctness($pk, $sk)
{
$group = $pk["group"];
$Zq = range(0, $group["order"] - 1);
foreach ($group["G"] as $m) {
foreach ($Zq as $scalar) {
if (_DEBUG >= 8) {
echo "Checking ElGamal scalar exp for {$m} and {$scalar}...";
}
$c = ElG_Enc($m, $pk);
$cmult = ElG_ScalarExp($c, $scalar, $pk);
if (modular_exp($m, $scalar, $group["modulo"]) != ElG_Dec($cmult, $pk, $sk)) {
if (_DEBUG >= 1) {
echo "\nERROR : ElGamal homomorphic scalar exponentiation error for m = {$m} and scalar = {$scalar}\n";
}
return false;
}
if (_DEBUG >= 8) {
echo "\n";
}
}
}
return 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";
echo "\tMult: ", $cumul["mult"] / $limit, "ms\n";
echo "\tPlainMult: ", $cumul["plainmult"] / $limit, "ms\n";
echo "\tScalarExp: ", $cumul["scexp"] / $limit, "ms\n";
echo "\tRerand: ", $cumul["rerand"] / $limit, "ms\n";