Question

我有以下PHP示例，我试图模仿C＃。它使用AES 128bit ECB加密和PKCS7填充：

$trust_jsonString="hello";
echo "input: '" . $trust_jsonString . "'\n";
echo "input (dump): " . var_dump($trust_jsonString) . "\n";

$trust_key = "9840822c-14fc-49ac-9d68-ac532f9f171e";
echo "key: '" . $trust_key . "'\n";

$blockSize=mcrypt_get_block_size(MCRYPT_RIJNDAEL_128,MCRYPT_MODE_ECB);
echo "block size: '" . $blockSize . "'\n";

$padding = $blockSize - (strlen($trust_jsonString) % $blockSize);
echo "padding: '" . $padding . "'\n";

$trust_jsonString .= str_repeat(chr($padding), $padding);

$trust_jsonString = utf8_encode($trust_jsonString);
echo "utf8 json: '" . $trust_jsonString . "'\n";
echo "utf8 json (dump): " . var_dump($trust_jsonString) . "\n";

$trust_key=utf8_encode($trust_key);
echo "encoded key: " . $trust_key . "\n";

$trust_key=(md5($trust_key));
echo "md5 hash of key (raw): " . $trust_key . "\n";

$mcrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $trust_key, $trust_jsonString, MCRYPT_MODE_ECB);
echo "mcrypt (raw): " . var_dump($mcrypt) . "\n";
echo "mcrypt: " . $mcrypt . "\n";

echo "mcrypt (raw): ";
$byte_array = byteStr2byteArray($mcrypt);
for($i=0;$i<count($byte_array);$i++)
{
   printf("%02x", $byte_array[$i]);
}
echo "\n";

$presid = base64_encode($mcrypt);
echo "presid: " . $presid . "\n";

$sid=strtr($presid,'+/', '-_');
echo "sid: " . $sid . "\n";

function byteStr2byteArray($s) {
    return array_slice(unpack("C*", "\0".$s), 1);
}

我目前正在运行以下C＃代码以尝试模仿结果：

static void Main( string[] args )
{
    string data = "hello";
    Encrypt(data);
}

static void Encrypt( string data )
{
    PaddingMode padding = PaddingMode.PKCS7;
    CipherMode cipherMode = CipherMode.ECB;
    int size = 128;

    Console.WriteLine("input: '" + data + "'");

    string officialKey = "9840822c-14fc-49ac-9d68-ac532f9f171e";
    Console.WriteLine("key: '" + officialKey + "'");

    Console.WriteLine("block size: '16'");
    Console.WriteLine( "padding: '11'" );

    var utf8dataBytes = Encoding.UTF8.GetBytes(data);
    var utf8data = Encoding.UTF8.GetString(utf8dataBytes);
    Console.WriteLine("utf8 json: '" + utf8data + "'");

    Console.WriteLine("encoded key (utf8): " + officialKey);

    var utf8KeyBytes = Encoding.UTF8.GetBytes(officialKey);

    var myMD5 = MD5.Create();
    var md5HashOfKey = myMD5.ComputeHash(utf8KeyBytes);

    Console.WriteLine( "md5 hash of key (raw): " + DumpBinary(md5HashOfKey) );

    byte[] encryptedBlob;

    using ( var aes = new AesManaged() )
    {
        try
        {
            aes.Padding = PaddingMode.PKCS7;
            aes.Mode = CipherMode.ECB;
            aes.KeySize = 128;
            aes.BlockSize = 128;
            aes.Key = md5HashOfKey;
            //aes.IV = new byte[] { 0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0 };

            var bytes = utf8dataBytes;
            //var bytes = ForcePaddingManually( utf8dataBytes );

            var cxform = aes.CreateEncryptor();
            encryptedBlob = cxform.TransformFinalBlock( bytes, 0, bytes.Length );
        }
        finally
        {
            aes.Clear();
        }
    }

    //var encryptedBlob = AesAlgo.Encrypt( data, md5HashOfKey, padding, cipherMode, size );
    Console.WriteLine("mcrypt (raw): " + DumpBinary(encryptedBlob));
    Console.WriteLine("mcrypt: " + Encoding.UTF8.GetString(encryptedBlob));

    var encryptedBase64 = Convert.ToBase64String(encryptedBlob);
    Console.WriteLine( "presid: " + encryptedBase64 );

    var encodedEncryptedBlob = encryptedBase64.Replace( "+", "-" ).Replace( "/", "_" );
    Console.WriteLine( "sid: " + encodedEncryptedBlob );
    Console.WriteLine("COMPLETE!");
}

static byte[] ForcePaddingManually( byte[] data )
{
    // force padding manually to test that PKCS7 works like we are expecting
    var pad = ( 16 - data.Length % 16 ) % 16;
    var bytes = new byte[data.Length + pad];
    for ( int i = 0; i < data.Length; ++i )
    {
        bytes[i] = data[i];
    }
    for ( int i = data.Length; i < data.Length + pad; ++i )
    {
        bytes[i] = (byte)pad;
    }

    return bytes;
}

static string DumpBinary( byte[] data )
{
    var sb = new StringBuilder();
    for ( int i = 0; i < data.Length; ++i )
    {
        sb.Append( data[i].ToString( "X2" ) );
    }
    return sb.ToString();
}

当我查看这些结果时，这就是我得到的结果：

PHP：

input: 'hello'
string(5) "hello"
input (dump): 
key: '9840822c-14fc-49ac-9d68-ac532f9f171e'
block size: '16'
padding: '11'
utf8 json: 'hello'
string(16) "hello"
utf8 json (dump): 
encoded key: 9840822c-14fc-49ac-9d68-ac532f9f171e
md5 hash of key (raw): 6d334201cb7625323da32e0c31b2b138
string(16) "�Ҙ�= �˹��C���"
mcrypt (raw): 
mcrypt: �Ҙ�= �˹��C���
mcrypt (raw): b0d298c83d20a0cbb9f0ea4305cef2ec
presid: sNKYyD0goMu58OpDBc7y7A==
sid: sNKYyD0goMu58OpDBc7y7A==

C＃：

input: 'hello'
key: '9840822c-14fc-49ac-9d68-ac532f9f171e'
block size: '16'
padding: '11'
utf8 json: 'hello'
encoded key (utf8): 9840822c-14fc-49ac-9d68-ac532f9f171e
md5 hash of key (raw): 6D334201CB7625323DA32E0C31B2B138
mcrypt (raw): 4CBAD7678AAB2B054371A1B572161280
mcrypt: L??g??+♣Cq??r▬↕?
presid: TLrXZ4qrKwVDcaG1chYSgA==
sid: TLrXZ4qrKwVDcaG1chYSgA==
COMPLETE!

其中有很多诊断和misc代码，但基本问题是当传入密钥的相同MD5哈希值（二进制文件相同）并且传入相同的输入数据时（字节是相同，或者我可以强制填充在输入的C＃代码中相同）我得到不同的输出结果。我确信这很简单，但它并没有突然出现在我面前。有人可以在这里找出问题吗？

基本问题是底部显示的SID（AES加密结果）是不同的 - 导致差异的原因是什么？

Answer 1

主要问题是PHP代码中的实际密钥是由md5()创建的，没有用于获取原始输出的可选参数。这意味着实际密钥长度为32个字节，因为它是十六进制编码的，并且在没有解码的情况下按原样使用。基本上，你在这里处理AES-256。

由于您无法更改PHP代码，因此需要在C＃中重新创建此事故：

aes.KeySize = 256;
aes.Key = Encoding.ASCII.GetBytes(BitConverter.ToString(md5HashOfKey).Replace("-","").ToLower());

按预期输出：

mcrypt (raw): B0D298C83D20A0CBB9F0EA4305CEF2EC
mcrypt: �Ҙ�= �˹��C���
presid: sNKYyD0goMu58OpDBc7y7A==
sid: sNKYyD0goMu58OpDBc7y7A==

BitConverter.ToString()返回“6D-33-42-01 -....”形式的十六进制字符串，这意味着必须删除短划线并且必须将其转换为小写以创建实际的密钥

DEMO

Answer 2

首先，有助于缩小问题范围的是密钥（原始）的＆＃34; md5哈希：＆＃34;在两种情况下都是相同的，但base64编码不匹配密钥（base64）的＆＃34; md5哈希：＆＃34;，因此这种情况会缩小问题与代码的差异。 base64call。

注意您的输入是十六进制字符串，而不是PHP中的二进制字符串。

使用专门针对hex64的十六进制字符串的在线转换器进行测试，我可以验证bTNCAct2JTI9oy4MMbKxOA==是正确的base64编码，用于匹配C＃输出的0x6d334201cb7625323da32e0c31b2b138输入。

这意味着PHP的base64编码是罪魁祸首。可能有更好的方法来检索二进制中的密钥，但您需要做的是将十六进制字符串转换为二进制：

<?php
echo base64_encode(pack("H*" , '6d334201cb7625323da32e0c31b2b138')) ;
?>

这会产生bTNCAct2JTI9oy4MMbKxOA==

的预期输出

可能存在更多问题，但这解释了输出的差异。

将PHP AES 128 ECB加密与C＃

2 个答案: