解决密码学结果差异

Question

我有一个不错的课程来加密和解密数据。我可以通过此字符串将其传递：

var thisIsATest = "This is a test.";

当我解密数据时，我会回来：

var thisIsDecrypted = "This is a test.\0";

我们俩都理解这些基本上是同一件事，但它仍然不会通过我的单位测试。

首先，我将显示单位测试：

var privateKey = Encryption.GetPrivateKey();
var password = new byte[] { 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A };
var salt = Salt.CreateSalt();
var passPhrase = Encryption.PasswordAndSalt(password, salt);
var thisIsATest = "This is a test.";
var clearArray = Encoding.UTF8.GetBytes(thisIsATest);
var cypherArray = Encryption.Encrypt(clearArray, passPhrase, privateKey);
var decryptedArray = Encryption.Decrypt(cypherArray, passPhrase, privateKey);
var thisIsDecrypted = Encoding.UTF8.GetString(decryptedArray);
//Assert
Assert.IsTrue(thisIsATest == thisIsDecrypted);

这是我的代码，解密：

public static byte[] Decrypt(byte[] cypherBytes, byte[] passPhrase, byte[] privateKey)
{
    var result = new byte[] { };
    using (var rijndael = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7 })
    {
        using (var decryptor = rijndael.CreateDecryptor(passPhrase, privateKey))
        {
            using (var ms = new MemoryStream(cypherBytes))
            {
                using (var cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
                {
                    result = new byte[cypherBytes.Length];
                    var readCount = cs.Read(result, 0, result.Length);
                }
            }
        }
        rijndael.Clear();
    }
    return result;
}

加密：

public static byte[] Encrypt(byte[] clearBytes, byte[] passPhrase, byte[] privateKey)
{
    var result = new byte[] { };
    using (var rijndael = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7 })
    {
        using (var encryptor = rijndael.CreateEncryptor(passPhrase, privateKey))
        {
            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
                {
                    cs.Write(clearBytes, 0, clearBytes.Length);
                    cs.FlushFinalBlock();
                }
                result = ms.ToArray();
            }
        }
        rijndael.Clear();
    }
    return result;
}

passwordandsalt：

public const int INITIALIZATION_VECTOR_SIZE = 32;

public static byte[] PasswordAndSalt(byte[] password, byte[] salt)
{
    var result = new byte[] { };
    using (var pwd = new PasswordDeriveBytes(password, salt))
    {
        result = pwd.GetBytes(INITIALIZATION_VECTOR_SIZE);
    }
    return result;
}

is paddingmode.pkcs7 导致我的缓冲区在最后获得\ 0 ？

解决！

在下面使用Maarten的答案，我能够重写解密方法以成功工作如下：

public static byte[] Decrypt(byte[] cypherBytes, byte[] passPhrase, byte[] privateKey)
{
    var result = new byte[] { };
    using (var rijndael = new RijndaelManaged() { Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7 })
    {
        using (var decryptor = rijndael.CreateDecryptor(passPhrase, privateKey))
        {
            using (var ms = new MemoryStream(cypherBytes))
            {
                using (var cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
                {
                    var array = new byte[cypherBytes.Length];
                    var readCount = cs.Read(array, 0, array.Length);
                    result = new byte[readCount];
                    Array.Copy(array, result, readCount);
                }
            }
        }
        rijndael.Clear();
    }
    return result;
}

Answer 1

错误的问题：您自己设置了缓冲区的大小。最后一个字节永远不会被人填充。

您为什么假设使用填充的CBC模式假设明文的大小与密文的大小相同？您不应忽略readCount，然后仅将缓冲区的最左侧部分用作明文。

具有PKCS＃7填充的CBC模式将使用1到N字节填充，其中N是该算法的块大小。对于AES始终是16个字节。因此，您的缓冲区将始终在您当前的代码中被过度尺寸。