c# - DES-ECB加解密

Question

我在我的应用程序中使用 DES-ECB + base64 加密。这就是我称之为“Crypto”的类的代码

public class Crypto
{

    public static string Decrypt(string encryptedString)
    {
        DESCryptoServiceProvider desProvider = new DESCryptoServiceProvider();
        desProvider.Mode = CipherMode.ECB;
        desProvider.Padding = PaddingMode.PKCS7;
        desProvider.Key = Encoding.ASCII.GetBytes("e5d66cf8");
        using (MemoryStream stream = new MemoryStream(Convert.FromBase64String(encryptedString)))
        {
            using (CryptoStream cs = new CryptoStream(stream, desProvider.CreateDecryptor(), CryptoStreamMode.Read))
            {
                using (StreamReader sr = new StreamReader(cs, Encoding.ASCII))
                {
                    return sr.ReadToEnd();
                }
            }
        }
    }

    public static string Encrypt(string decryptedString)
    {
        DESCryptoServiceProvider desProvider = new DESCryptoServiceProvider();
        desProvider.Mode = CipherMode.ECB;
        desProvider.Padding = PaddingMode.PKCS7;
        desProvider.Key = Encoding.ASCII.GetBytes("e5d66cf8");
        using (MemoryStream stream = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(stream, desProvider.CreateEncryptor(), CryptoStreamMode.Write))
            {
                byte[] data = Encoding.Default.GetBytes(decryptedString);
                cs.Write(data, 0, data.Length);
                return Convert.ToBase64String(stream.ToArray());
            }
        }
    }
}

但是当我加密一个字符串，然后再次解密并再次加密时，加密的字符串与之前加密的字符串不同。这就是第一个加密字符串:

kEN0HUp/dqz8kXA7nYivJG6Jl3haLJjhBq1UfEtQTwaPwizW//03M0UxF8dBuYZo2BoZ5vsVcXRJF1LpFZLWxDsdeKAC43L2K2OoYRxTn/dA6KmM13YS9xOezGiROQfVj5qrkdokJRCvj0gYfFoH2oeDGyN+EAw5Dgzsp697kj4=

这是第二个加密字符串:

kEN0HUp/dqz8kXA7nYivJG6Jl3haLJjhBq1UfEtQTwaPwizW//03M0UxF8dBuYZo2BoZ5vsVcXRJF1LpFZLWxDsdeKAC43L2K2OoYRxTn/dA6KmM13YS9xOezGiROQfVj5qrkdokJRCvj0gYfFoH2oeDGyN+EAw5

它们几乎相同，除了第一个字符串中的“Dgzsp697kj4=”。
怎么了？
提前致谢。

Answer 1

您正在丢失数据。在您的 Encrypt() 方法中，您需要调用 Encrypt Final Block() 来让填充算法知道您已完成，以便它可以添加填充:

using (CryptoStream cs = new CryptoStream(stream, desProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
  byte[] data = Encoding.Default.GetBytes(decryptedString);
  cs.Write(data, 0, data.Length);
  cs.FlushFinalBlock(); // <-- Add this
  return Convert.ToBase64String(stream.ToArray());
}