<?php
/**
 * Created by PhpStorm.
 * User: Kevin
 * Date: 2023/9/6
 * Time: 11:27
 * File Description: 国密算法SM4 对称加密
 */

namespace lib;


class SM4
{
    const SM4_CK = [
        0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
        0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
        0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
        0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
        0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
        0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
        0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
        0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
    ];

    const SM4_SBOX = [
        0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
        0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
        0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
        0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
        0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
        0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
        0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
        0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
        0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
        0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
        0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
        0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
        0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
        0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
        0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
        0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48
    ];

    const SM4_FK = [0xA3B1BAC6, 0x56AA3350, 0x677D9197, 0xB27022DC];

    public $_rk = [];
    public $_block_size = 16;

    public function __construct()
    {
    }

    public function encrypt($key, $data)
    {
        $this->sM4KeySchedule($key);

        $bytes = $this->pad($data, $this->_block_size);
        $chunks = array_chunk($bytes, $this->_block_size);

        $ciphertext = "";
        foreach ($chunks as $chunk) {
            $ciphertext .= $this->sM4Encrypt($chunk);
        }

        return base64_encode($ciphertext);
    }

    public function decrypt($key, $data)
    {
        $data = base64_decode($data);
        if (strlen($data) < 0 || strlen($data) % $this->_block_size != 0) {
            return false;
        }

        $this->sM4KeySchedule($key);
        $bytes = unpack("C*", $data);
        $chunks = array_chunk($bytes, $this->_block_size);

        $plaintext = "";
        foreach ($chunks as $chunk) {
            $plaintext .= substr($this->sM4Decrypt($chunk), 0, 16);
        }
        $plaintext = $this->un_pad($plaintext);

        return $plaintext;
    }

    private function sM4Decrypt($cipherText)
    {
        $x = [];
        for ($j = 0; $j < 4; $j++) {
            $x[$j] = ($cipherText[$j * 4] << 24) | ($cipherText[$j * 4 + 1] << 16) | ($cipherText[$j * 4 + 2] << 8) | ($cipherText[$j * 4 + 3]);
        }

        for ($i = 0; $i < 32; $i++) {
            $tmp = $x[$i + 1] ^ $x[$i + 2] ^ $x[$i + 3] ^ $this->_rk[31 - $i];
            $buf = (self::SM4_SBOX[($tmp >> 24) & 0xFF]) << 24 | (self::SM4_SBOX[($tmp >> 16) & 0xFF]) << 16 | (self::SM4_SBOX[($tmp >> 8) & 0xFF]) << 8 | (self::SM4_SBOX[$tmp & 0xFF]);
            $x[$i + 4] = $x[$i] ^ ($buf ^ $this->sm4Rotl32(($buf), 2) ^ $this->sm4Rotl32(($buf), 10) ^ $this->sm4Rotl32(($buf), 18) ^ $this->sm4Rotl32(($buf), 24));
        }

        $plainText = [];
        for ($k = 0; $k < 4; $k++) {
            $plainText[4 * $k] = ($x[35 - $k] >> 24) & 0xFF;
            $plainText[4 * $k + 1] = ($x[35 - $k] >> 16) & 0xFF;
            $plainText[4 * $k + 2] = ($x[35 - $k] >> 8) & 0xFF;
            $plainText[4 * $k + 3] = ($x[35 - $k]) & 0xFF;
        }

        return $this->bytesToString($plainText);
    }

    private function sM4Encrypt($plainText)
    {
        $x = [];
        for ($j = 0; $j < 4; $j++) {
            $x[$j] = ($plainText[$j * 4] << 24) | ($plainText[$j * 4 + 1] << 16) | ($plainText[$j * 4 + 2] << 8) | ($plainText[$j * 4 + 3]);
        }

        for ($i = 0; $i < 32; $i++) {
            $tmp = $x[$i + 1] ^ $x[$i + 2] ^ $x[$i + 3] ^ $this->_rk[$i];
            $buf = (self::SM4_SBOX[($tmp >> 24) & 0xFF]) << 24 | (self::SM4_SBOX[($tmp >> 16) & 0xFF]) << 16 | (self::SM4_SBOX[($tmp >> 8) & 0xFF]) << 8 | (self::SM4_SBOX[$tmp & 0xFF]);
            $x[$i + 4] = $x[$i] ^ ($buf ^ $this->sm4Rotl32(($buf), 2) ^ $this->sm4Rotl32(($buf), 10) ^ $this->sm4Rotl32(($buf), 18) ^ $this->sm4Rotl32(($buf), 24));
        }

        $cipherText = [];
        for ($k = 0; $k < 4; $k++) {
            $cipherText[4 * $k] = ($x[35 - $k] >> 24) & 0xFF;
            $cipherText[4 * $k + 1] = ($x[35 - $k] >> 16) & 0xFF;
            $cipherText[4 * $k + 2] = ($x[35 - $k] >> 8) & 0xFF;
            $cipherText[4 * $k + 3] = ($x[35 - $k]) & 0xFF;
        }

        return $this->bytesToString($cipherText);
    }

    private function stringToBytes($string)
    {
        return unpack('C*', $string);
    }

    private function bytesToString($bytes)
    {
        return vsprintf(str_repeat('%c', count($bytes)), $bytes);
    }

    private function pad($data)
    {
        $bytes = $this->stringToBytes($data);
        $rem = $this->_block_size - count($bytes) % $this->_block_size;
        for ($i = 0; $i < $rem; $i++) {
            array_push($bytes, $rem);
        }
        return $bytes;
    }

    private function un_pad($data)
    {
        $bytes = $this->stringToBytes($data);
        $rem = $bytes[count($bytes)];
        $bytes = array_slice($bytes, 0, count($bytes) - $rem);
        return $this->bytesToString($bytes);
    }

    private function sm4Rotl32($buf, $n)
    {
        return (($buf << $n) & 0xffffffff) | ($buf >> (32 - $n));
    }

    private function sM4KeySchedule($key)
    {
        $this->_rk = [];
        $key = array_values(unpack("C*", $key));

        $k = [];
        for ($i = 0; $i < 4; $i++) {
            $k[$i] = self::SM4_FK[$i] ^ (($key[4 * $i] << 24) | ($key[4 * $i + 1] << 16) | ($key[4 * $i + 2] << 8) | ($key[4 * $i + 3]));
        }

        for ($j = 0; $j < 32; $j++) {
            $tmp = $k[$j + 1] ^ $k[$j + 2] ^ $k[$j + 3] ^ self::SM4_CK[$j];
            $buf = (self::SM4_SBOX[($tmp >> 24) & 0xFF]) << 24 | (self::SM4_SBOX[($tmp >> 16) & 0xFF]) << 16 | (self::SM4_SBOX[($tmp >> 8) & 0xFF]) << 8 | (self::SM4_SBOX[$tmp & 0xFF]);

            $k[$j + 4] = $k[$j] ^ (($buf) ^ ($this->sm4Rotl32(($buf), 13)) ^ ($this->sm4Rotl32(($buf), 23)));
            $this->_rk[$j] = $k[$j + 4];
        }
    }

}