php7实现MS4加解密代码

MS4是一种加密算法，它包括加密和解密两个过程。下面是PHP 7中实现MS4加解密的代码示例：

<?php

class MS4
{
    const BLOCK_SIZE = 8;
    const ROUNDS = 10;

    private $key;
    private $sbox;

    public function __construct($key)
    {
        $this->key = $this->expandKey($key);
        $this->sbox = $this->generateSBox();
    }

    public function encrypt($plaintext)
    {
        $blocks = $this->pad($plaintext);
        $ciphertext = '';

        foreach ($blocks as $block) {
            $x = $this->byteArrayToInt($block);
            for ($i = 0; $i < self::ROUNDS; $i++) {
                $x = $this->substitute($x);
                $x = $this->permute($x);
                $x ^= $this->key[$i];
            }
            $ciphertext .= $this->intToByteArray($x);
        }

        return $ciphertext;
    }

    public function decrypt($ciphertext)
    {
        $blocks = str_split($ciphertext, self::BLOCK_SIZE);
        $plaintext = '';

        foreach ($blocks as $block) {
            $x = $this->byteArrayToInt($block);
            for ($i = self::ROUNDS - 1; $i >= 0; $i--) {
                $x ^= $this->key[$i];
                $x = $this->permuteInverse($x);
                $x = $this->substituteInverse($x);
            }
            $plaintext .= $this->intToByteArray($x);
        }

        return $this->unpad($plaintext);
    }

    private function expandKey($key)
    {
        $expandedKey = [];
        $keyLength = strlen($key);

        for ($i = 0; $i < self::ROUNDS; $i++) {
            $keyIndex = $i % $keyLength;
            $expandedKey[$i] = ord($key[$keyIndex]);
        }

        return $expandedKey;
    }

    private function generateSBox()
    {
        $sbox = [];

        for ($i = 0; $i < 256; $i++) {
            $sbox[$i] = $i ^ 0x55;
        }

        return $sbox;
    }

    private function substitute($x)
    {
        $y = 0;

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $byte = ($x >> ($i * 8)) & 0xFF;
            $substitutedByte = $this->sbox[$byte];
            $y |= $substitutedByte << ($i * 8);
        }

        return $y;
    }

    private function substituteInverse($y)
    {
        $x = 0;

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $byte = ($y >> ($i * 8)) & 0xFF;
            $substitutedByte = $this->sbox[$byte];
            $x |= $substitutedByte << ($i * 8);
        }

        return $x;
    }

    private function permute($x)
    {
        $y = 0;

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $byte = ($x >> ($i * 8)) & 0xFF;
            $permutatedByte = (($byte << 1) | ($byte >> 7)) & 0xFF;
            $y |= $permutatedByte << ($i * 8);
        }

        return $y;
    }

    private function permuteInverse($y)
    {
        $x = 0;

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $byte = ($y >> ($i * 8)) & 0xFF;
            $permutatedByte = (($byte >> 1) | ($byte << 7)) & 0xFF;
            $x |= $permutatedByte << ($i * 8);
        }

        return $x;
    }

    private function pad($data)
    {
        $padLength = self::BLOCK_SIZE - (strlen($data) % self::BLOCK_SIZE);
        $padding = str_repeat(chr($padLength), $padLength);
        return str_split($data . $padding, self::BLOCK_SIZE);
    }

    private function unpad($data)
    {
        $padLength = ord($data[strlen($data) - 1]);
        return substr($data, 0, strlen($data) - $padLength);
    }

    private function byteArrayToInt($byteArray)
    {
        $intValue = 0;

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $intValue |= ord($byteArray[$i]) << ($i * 8);
        }

        return $intValue;
    }

    private function intToByteArray($intValue)
    {
        $byteArray = '';

        for ($i = 0; $i < self::BLOCK_SIZE; $i++) {
            $byteArray .= chr(($intValue >> ($i * 8)) & 0xFF);
        }

        return $byteArray;
    }
}

$key = 'secretkey';
$plaintext = 'hello world';

$ms4 = new MS4($key);
$ciphertext = $ms4->encrypt($plaintext);
$decrypted = $ms4->decrypt($ciphertext);

echo "Plaintext: $plaintext\n";
echo "Ciphertext: $ciphertext\n";
echo "Decrypted: $decrypted\n";

在上面的示例中，我们定义了一个MS4类，它包含了MS4加密和解密的方法。在构造函数中，我们将密钥扩展为一个长度为10的数组，并生成S盒。在加密过程中，我们将明文分割成8字节的块，并对每个块执行10轮加密。在加密过程中，我们将密钥的每个字节与S盒进行异或操作，并进行置换和代替操作。在解密过程中，我们将密文分割成8字节的块，并对每个块执行10轮解密，我们也将密钥的每个字节与S盒进行异或操作，并进行置换和代替操作。最后，我们将解密后的块组合成明文并去除填充。