Some BINKP optimisation, implemented crypt, implemented receiving compressed transfers

app/Classes/Crypt.php

@@ -0,0 +1,97 @@
+<?php
+
+namespace App\Classes;
+
+use App\Interfaces\CRC as CRCInterface;
+
+class Crypt implements CRCInterface
+{
+	private array $keys= [
+		305419896,
+		591751049,
+		878082192,
+	];
+
+	public function __construct(string $password)
+	{
+		$this->extend_key($password);
+	}
+
+	/**
+	 * Update crc.
+	 */
+	private function crc32_cr(int $oldCrc, int $charAt): int
+	{
+		return (($oldCrc >> 8) & 0xFFFFFF) ^ self::crc32_tab[($oldCrc ^ $charAt) & 0xFF];
+	}
+
+	public function decrypt(string $content): string
+	{
+		$result = '';
+
+		foreach (unpack('C*', $content) as $byte) {
+			$byte = ($byte ^ $this->decrypt_byte()) & 0xFF;
+			$this->update_keys($byte);
+			$result .= chr($byte);
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Decrypt byte.
+	 */
+	private function decrypt_byte(): int
+	{
+		$temp = $this->keys[2] | 2;
+
+		return (($temp * ($temp ^ 1)) >> 8) & 0xFFFFFF;
+	}
+
+	public function encrypt(string $content): string
+	{
+		$result = '';
+
+		foreach (unpack('C*', $content) as $val)
+			$result .= pack('c', $this->encrypt_byte($val));
+
+		return $result;
+	}
+
+	private function encrypt_byte(int $byte): int
+	{
+		$result = $byte ^ $this->decrypt_byte() & 0xFF;
+		$this->update_keys($byte);
+
+		return $result;
+	}
+
+	public function extend_key(string $password): void
+	{
+		foreach (unpack('C*', $password) as $byte)
+			$this->update_keys($byte);
+	}
+
+	public static function toSignedInt32(int $int): int
+	{
+		if (\PHP_INT_SIZE === 8) {
+			$int &= 0xFFFFFFFF;
+
+			if ($int & 0x80000000)
+				return $int - 0x100000000;
+		}
+
+		return $int;
+	}
+
+	/**
+	 * Update keys.
+	 */
+	private function update_keys(int $byte): void
+	{
+		$this->keys[0] = $this->crc32_cr($this->keys[0],$byte);
+		$this->keys[1] += ($this->keys[0] & 0xFF);
+		$this->keys[1] = $this->toSignedInt32($this->keys[1]*134775813+1);
+		$this->keys[2] = $this->toSignedInt32($this->crc32_cr($this->keys[2],($this->keys[1] >> 24) & 0xFF));
+	}
+}