tc-tea php

tc_tea.php

<?php

// TC-TEA for PHP by Jixun <https://jixun.moe>
// Licensed under MIT license

namespace TC_TEA {

    use Random\RandomException;

    const ROUNDS = 16;
    const DELTA = 0x9e3779b9;

    function u32(int $value): int
    {
        return $value & 0xffff_ffff;
    }

    function ecb_single_round(int $value, int $sum, int $key1, int $key2): int
    {
        $left = ($value << 4) + $key1;
        $right = ($value >> 5) + $key2;
        $mid = ($sum + $value);
        return $left ^ $mid ^ $right;
    }

    function ecb_encrypt(string $block, string $key): string
    {
        [, $y, $z] = unpack('N2', $block);
        [, $k0, $k1, $k2, $k3] = unpack('N4', $key);

        $sum = 0;
        for ($i = 0; $i < ROUNDS; $i++) {
            $sum += DELTA;
            $y = u32($y + ecb_single_round($z, $sum, $k0, $k1));
            $z = u32($z + ecb_single_round($y, $sum, $k2, $k3));
        }

        return pack('NN', $y, $z);
    }

    function ecb_decrypt(string $block, string $key): string
    {
        [, $y, $z] = unpack('N2', $block);
        [, $k0, $k1, $k2, $k3] = unpack('N4', $key);

        $sum = (ROUNDS * DELTA);
        for ($i = 0; $i < ROUNDS; $i++) {
            $z = u32($z - ecb_single_round($y, $sum, $k2, $k3));
            $y = u32($y - ecb_single_round($z, $sum, $k0, $k1));
            $sum = $sum - DELTA;
        }
        return pack('NN', $y, $z);
    }

    const kSaltLen = 2;
    const kZeroLen = 7;
    const kFixedPaddingLen = 1 + kSaltLen + kZeroLen;

    function xor_tea_block(string $s1, string $s2): string
    {
        assert(strlen($s1) == 8);
        assert(strlen($s2) == 8);

        $result = '';
        for ($i = 0; $i < 8; $i++) {
            $result .= $s1[$i] ^ $s2[$i];
        }
        return $result;
    }

    /**
     * tc_tea encrypt routine
     * @throws RandomException failed to generate random salt
     */
    function encrypt(string $data, string $key): string
    {
        $length = strlen($data) + kFixedPaddingLen;
        $paddingLength = (8 - ($length % 8)) % 8;
        $outputLength = $length + $paddingLength;

        $buffer = '';
        $headerLength = 1 + $paddingLength + kSaltLen;
        $buffer .= chr((random_int(0, 0x1f) << 3) | $paddingLength);
        $buffer .= random_bytes($headerLength - 1);
        $buffer .= $data;
        $buffer .= str_repeat("\0", 7);

        $result = '';
        $iv1 = str_repeat("\0", 8);
        $iv2 = str_repeat("\0", 8);
        for ($i = 0; $i < $outputLength; $i += 8) {
            $block = substr($buffer, $i, 8);
            $block = xor_tea_block($block, $iv1);
            $iv2_next = $block;
            $block = ecb_encrypt($block, $key);
            $block = xor_tea_block($block, $iv2);
            $iv1 = $block;
            $iv2 = $iv2_next;
            $result .= $block;
        }

        return $result;
    }

    /**
     * @throws \Exception
     */
    function decrypt(string $data, string $key): string
    {
        if (strlen($data) < 10 || strlen($data) % 8 != 0) {
            throw new \Exception('Invalid data length');
        }

        $len = strlen($data);
        $result = '';
        $iv1 = str_repeat("\0", 8);
        $iv2 = str_repeat("\0", 8);
        for ($i = 0; $i < $len; $i += 8) {
            $block = substr($data, $i, 8);
            $iv1_next = $block;
            $block = xor_tea_block($block, $iv2);
            $block = ecb_decrypt($block, $key);

            $iv2 = $block;
            $block = xor_tea_block($block, $iv1);
            $iv1 = $iv1_next;
            $result .= $block;
        }

        $blanks = substr($result, -7);
        $check = 0;
        for ($i = 0; $i < 7; $i++) {
            $check |= ord($blanks[$i]);
        }
        if ($check != 0) {
            throw new \Exception('Padding error');
        }

        $padSize = ord($result[0]) & 0x07;
        $startLoc = 1 + $padSize + 2;
        $endLoc = strlen($result) - 7;
        return substr($result, $startLoc, $endLoc - $startLoc);
    }
}

tc_tea_test.php

<?php

require_once 'tc_tea.php';

$d1 = \TC_TEA\ecb_decrypt("\x56\x27\x6b\xa9\x80\xb9\xec\x16", "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x00");
var_dump(bin2hex($d1));
assert($d1 === "\x01\x02\x03\x04\x05\x06\x07\x08");

mt_srand();
for ($i = 0; $i < 1000; $i++) {
    $v = \TC_TEA\decrypt(\TC_TEA\encrypt("wowowowow", "12345678ABCDEFGH"), "12345678ABCDEFGH");
    assert($v === "wowowowow");
}

$decrypted = \TC_TEA\decrypt(hex2bin("86ebcc7fa8a354f03fa7575e160b2d09c2238ccc13345a9d"), "12345678ABCDEFGH");

var_dump($decrypted);