DES-ECB加密和解密

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,然后再次解密并再加密一次时,加密的字符串与之前的加密字符串不同.这是第一个加密的字符串:

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

你正在丢失数据.在您的Encrypt()方法中,您需要调用EncryptFinalBlock()以使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());
}