Question

我打算在我的一个项目中使用TripleDES。我正在做一些实验来适应它。我理解三重DES的块大小是8字节所以我假设如果给出8字节的数据，我应该得到8字节的加密数据。但我得到的是：

Input Size   | Encrypted Size
.            | .
.            | .
6 bytes      | 8 bytes
7 bytes      | 8 bytes
8 bytes      | 16 bytes
9 bytes      | 16 bytes
.            | .
.            | .

这是正常的吗？这是它应该工作的方式。以下是我尝试使用三重DES的方法：



class TripleDESEncryption
{
    private readonly TripleDESCryptoServiceProvider engine;

    public TripleDESEncryption () : this (256) { }

    public TripleDESEncryption (int keySizeInBits) {
        engine = new TripleDESCryptoServiceProvider { KeySize = keySizeInBits };
        engine.GenerateKey ();
    }

    public byte[] Encrypt (byte[] plain) {
        return engine.CreateEncryptor ().TransformFinalBlock (plain, 0, plain.Length);
    }

    public byte[] Decrypt (byte[] encrypted) {
        return engine.CreateDecryptor ().TransformFinalBlock (encrypted, 0, encrypted.Length);
    }
}

class Program
{
    static readonly int MAX_TEXT_LENGTH = 128;

    static void Main (string[] args) {
        Console.WriteLine ("{0,10}{1,10}{2,10}{3,10}", "Algo", "Key Size", "Input Size", "Encrypted Size");

        var tripleDES = new TripleDESEncryption ();
        var input = new List<byte> ();

        for (int i = 0; i <= MAX_TEXT_LENGTH; i++) {
            var plain = input.ToArray ();
            var encrypted = tripleDES.Encrypt (plain);
            Console.WriteLine ("{0,10}{1,10}{2,10}{3,10}", "Triple DES", keySize, input.Count, encrypted.Length);
            input.Add (0x65);
        }

        Console.ReadLine ();
    }
}

class TripleDESEncryption { private readonly TripleDESCryptoServiceProvider engine; public TripleDESEncryption () : this (256) { } public TripleDESEncryption (int keySizeInBits) { engine = new TripleDESCryptoServiceProvider { KeySize = keySizeInBits }; engine.GenerateKey (); } public byte[] Encrypt (byte[] plain) { return engine.CreateEncryptor ().TransformFinalBlock (plain, 0, plain.Length); } public byte[] Decrypt (byte[] encrypted) { return engine.CreateDecryptor ().TransformFinalBlock (encrypted, 0, encrypted.Length); } } class Program { static readonly int MAX_TEXT_LENGTH = 128; static void Main (string[] args) { Console.WriteLine ("{0,10}{1,10}{2,10}{3,10}", "Algo", "Key Size", "Input Size", "Encrypted Size"); var tripleDES = new TripleDESEncryption (); var input = new List<byte> (); for (int i = 0; i <= MAX_TEXT_LENGTH; i++) { var plain = input.ToArray (); var encrypted = tripleDES.Encrypt (plain); Console.WriteLine ("{0,10}{1,10}{2,10}{3,10}", "Triple DES", keySize, input.Count, encrypted.Length); input.Add (0x65); } Console.ReadLine (); } }

Answer 1

TripleDESCryptoServiceProvider默认使用PKCS7-padding。这会将任何消息填充到块大小的下一个倍数。

为避免使用填充，只需将Padding - 属性设置为PaddingMode.None

即可

new TripleDESCryptoServiceProvider { 
  KeySize = keySizeInBits, 
  Padding = PaddingMode.None 
};

使用Triple DES时加密的数据大小

1 个答案: