C# AES RijndaelManaged() CBC和PaddingMode.Zeros在发布到PHP后似乎缺少16个字符
我有一个C#服务器发布到一个php服务器。在PHP端，JSON字符串的开头恰好缺少16个字符。现在PHP解密如下所示：
function Decrypt($data_base64)
{
global $key;
global $iv_size;
$ciphertext_dec = base64_decode($data_base64);
$iv_dec = substr($ciphertext_dec, 0, $iv_size);
$ciphertext_dec = substr($ciphertext_dec, $iv_size);
$plaintext_utf8_dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,
$ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
return $plaintext_utf8_dec;
}以及C#上的帖子：
aesCrypt = new RijndaelManaged();
aesCrypt.KeySize = 256;
aesCrypt.BlockSize = 128;
aesCrypt.Mode = CipherMode.CBC;
aesCrypt.Padding = PaddingMode.Zeros;
var started = new StartStopObject() { action = "online" };
string jsonser1 = new JavaScriptSerializer().Serialize(started);
Post(Encrypt(jsonser1));
private string Encrypt(string plainStr)
{
aesCrypt.GenerateIV();
byte[] encrypted;
ICryptoTransform crypto = aesCrypt.CreateEncryptor(aesCrypt.Key, aesCrypt.IV);
using (System.IO.MemoryStream msEncrypt = new System.IO.MemoryStream())
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, crypto, CryptoStreamMode.Write))
{
using (System.IO.StreamWriter swEncrypt = new System.IO.StreamWriter(csEncrypt))
{
swEncrypt.Write(plainStr);
}
encrypted = msEncrypt.ToArray();
}
return Convert.ToBase64String(encrypted);
}
public void Post(string data)
{
byte[] buffer = Encoding.UTF8.GetBytes("var1=" + data);
HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(posturl);
WebReq.Method = "POST";
WebReq.ContentType = "application/x-www-form-urlencoded";
WebReq.ContentLength = buffer.Length;
System.IO.Stream PostData = WebReq.GetRequestStream();
PostData.Write(buffer, 0, buffer.Length);
PostData.Close();
}PHP中的vardump和echo显示：
"UahqVaE2nrxrTAijsZmjXL8QF9YmcRXdcRUREaFp7LKlhy6StrXqMc7TDmCF4qRT8fZZOZ5ovY/vHySzP2u73cs66i7nG1ywXrGiZOHa4E9yiOFFruQegIy/6yqiPXf9“(1){ "var1"=> string(128) array} e"，"email":null，"realm":null，"script":null，"followtag":null，"autojoin":null}
正如您所看到的，JSON字符串的开头恰好缺少16个字符。( {"action":"online"，"email":null，"realm":null，"script":null，"followtag":null，"autojoin":null} )
回答 1
Stack Overflow用户
发布于 2013-07-06 10:24:33
CryptoStream不会自动在密文前面加上IV。PHP端正在截取消息的第一个块，并将其用作IV。
下面是一些重现该问题的示例PHP：
$ivSize = 32;
$key = hash('SHA256', 'hello world', true);
$iv = mcrypt_create_iv($ivSize);
$cipher = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key,
"This is some sample text where the first block will be cut off.", MCRYPT_MODE_CBC, $iv);
$firstBlock = substr($cipher, 0, $ivSize);
$remainingCipher = substr($cipher, $ivSize);
$plain = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $remainingCipher, MCRYPT_MODE_CBC, $firstBlock);
echo $plain;输出：
he first block will be cut off.https://stackoverflow.com/questions/17499024
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