static function encrypt($block, $ctx)
{
$RCON = GPG_Cipher::$RCON;
$S = GPG_Cipher::$S;
$T1 = GPG_Cipher::$T1;
$T2 = GPG_Cipher::$T2;
$T3 = GPG_Cipher::$T3;
$T4 = GPG_Cipher::$T4;
$r = 0;
$t0 = 0;
$t1 = 0;
$t2 = 0;
$t3 = 0;
$b = GPG_Utility::pack_octets($block);
$rounds = $ctx->rounds;
$b0 = $b[0];
$b1 = $b[1];
$b2 = $b[2];
$b3 = $b[3];
for ($r = 0; $r < $rounds - 1; $r++) {
$t0 = $b0 ^ $ctx->rk[$r][0];
$t1 = $b1 ^ $ctx->rk[$r][1];
$t2 = $b2 ^ $ctx->rk[$r][2];
$t3 = $b3 ^ $ctx->rk[$r][3];
$b0 = $T1[$t0 & 255] ^ $T2[$t1 >> 8 & 255] ^ $T3[$t2 >> 16 & 255] ^ $T4[GPG_Utility::zshift($t3, 24)];
$b1 = $T1[$t1 & 255] ^ $T2[$t2 >> 8 & 255] ^ $T3[$t3 >> 16 & 255] ^ $T4[GPG_Utility::zshift($t0, 24)];
$b2 = $T1[$t2 & 255] ^ $T2[$t3 >> 8 & 255] ^ $T3[$t0 >> 16 & 255] ^ $T4[GPG_Utility::zshift($t1, 24)];
$b3 = $T1[$t3 & 255] ^ $T2[$t0 >> 8 & 255] ^ $T3[$t1 >> 16 & 255] ^ $T4[GPG_Utility::zshift($t2, 24)];
}
$r = $rounds - 1;
$t0 = $b0 ^ $ctx->rk[$r][0];
$t1 = $b1 ^ $ctx->rk[$r][1];
$t2 = $b2 ^ $ctx->rk[$r][2];
$t3 = $b3 ^ $ctx->rk[$r][3];
$b[0] = GPG_Cipher::F1($t0, $t1, $t2, $t3) ^ $ctx->rk[$rounds][0];
$b[1] = GPG_Cipher::F1($t1, $t2, $t3, $t0) ^ $ctx->rk[$rounds][1];
$b[2] = GPG_Cipher::F1($t2, $t3, $t0, $t1) ^ $ctx->rk[$rounds][2];
$b[3] = GPG_Cipher::F1($t3, $t0, $t1, $t2) ^ $ctx->rk[$rounds][3];
return GPG_Utility::unpack_octets($b);
}
