求解DES加密解密，解密没问题，就是解密总是提示“要解密的数据的长度无效。”

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Security.Cryptography;

namespace DESSampleForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("Key");
            byte[] encrypted;
            // Create an TripleDESCryptoServiceProvider object
            // with the specified key and IV.
            using (TripleDESCryptoServiceProvider tdsAlg = new TripleDESCryptoServiceProvider())
            {
                tdsAlg.Key = Key;
                tdsAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform encryptor = tdsAlg.CreateEncryptor(tdsAlg.Key, tdsAlg.IV);

                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {

                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                        encrypted = msEncrypt.ToArray();
                    }
                }
            }


            // Return the encrypted bytes from the memory stream.
            return encrypted;

        }

        static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("Key");

            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;

            // Create an TripleDESCryptoServiceProvider object
            // with the specified key and IV.
            using (TripleDESCryptoServiceProvider tdsAlg = new TripleDESCryptoServiceProvider())
            {
                tdsAlg.Key = Key;
                tdsAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = tdsAlg.CreateDecryptor(tdsAlg.Key, tdsAlg.IV);

                // Create the streams used for decryption.
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }

            }

            return plaintext;

        }

        private void button1_Click(object sender, EventArgs e)
        {
            TripleDESCryptoServiceProvider myTripleDES = new TripleDESCryptoServiceProvider();
            byte[] encrypted = EncryptStringToBytes(textBox1.Text.Trim(), myTripleDES.Key, myTripleDES.IV);
            textBox2.Text =Convert.ToBase64String(encrypted.ToArray());
        }

        private void button2_Click(object sender, EventArgs e)
        {
            TripleDESCryptoServiceProvider myTripleDES = new TripleDESCryptoServiceProvider();
            byte[] temp = System.Text.Encoding.Default.GetBytes(textBox2.Text.Trim());
            textBox3.Text = DecryptStringFromBytes(temp, myTripleDES.Key, myTripleDES.IV);
        }
    }
}

---

Raymond

Answer 1

你好：

我对这一块也不是太熟，但是查了一下MSDN文档：

TripleDESCryptoServiceProvider Class

文档里面已经提供了完整的加解密的方法，你的代码应该是有问题的， 因为在加密和解密的方法里面各自使用了自己的key和IV

以下是MSDN中在内存里面进行加解密的示例代码，你可以参考着修改一下你自己的代码：

using System;
using System.Security.Cryptography;
using System.Text;
using System.IO;

class TrippleDESCSPSample
{

    static void Main()
    {
        try
        {
            // Create a new TripleDESCryptoServiceProvider object 
            // to generate a key and initialization vector (IV).
            TripleDESCryptoServiceProvider tDESalg = new TripleDESCryptoServiceProvider();

            // Create a string to encrypt. 
            string sData = "Here is some data to encrypt.";

            // Encrypt the string to an in-memory buffer. 
            byte[] Data = EncryptTextToMemory(sData, tDESalg.Key, tDESalg.IV);

            // Decrypt the buffer back to a string. 
            string Final = DecryptTextFromMemory(Data, tDESalg.Key, tDESalg.IV);

            // Display the decrypted string to the console.
            Console.WriteLine(Final);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }

    }

    public static byte[] EncryptTextToMemory(string Data,  byte[] Key, byte[] IV)
    {
        try
        {
            // Create a MemoryStream.
            MemoryStream mStream = new MemoryStream();

            // Create a CryptoStream using the MemoryStream  
            // and the passed key and initialization vector (IV).
            CryptoStream cStream = new CryptoStream(mStream, 
                new TripleDESCryptoServiceProvider().CreateEncryptor(Key, IV), 
                CryptoStreamMode.Write);

            // Convert the passed string to a byte array. 
            byte[] toEncrypt = new ASCIIEncoding().GetBytes(Data);

            // Write the byte array to the crypto stream and flush it.
            cStream.Write(toEncrypt, 0, toEncrypt.Length);
            cStream.FlushFinalBlock();

            // Get an array of bytes from the  
            // MemoryStream that holds the  
            // encrypted data. 
            byte[] ret = mStream.ToArray();

            // Close the streams.
            cStream.Close();
            mStream.Close();

            // Return the encrypted buffer. 
            return ret;
        }
        catch(CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            return null;
        }

    }

    public static string DecryptTextFromMemory(byte[] Data,  byte[] Key, byte[] IV)
    {
        try
        {
            // Create a new MemoryStream using the passed  
            // array of encrypted data.
            MemoryStream msDecrypt = new MemoryStream(Data);

            // Create a CryptoStream using the MemoryStream  
            // and the passed key and initialization vector (IV).
            CryptoStream csDecrypt = new CryptoStream(msDecrypt, 
                new TripleDESCryptoServiceProvider().CreateDecryptor(Key, IV), 
                CryptoStreamMode.Read);

            // Create buffer to hold the decrypted data. 
            byte[] fromEncrypt = new byte[Data.Length];

            // Read the decrypted data out of the crypto stream 
            // and place it into the temporary buffer.
            csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);

            //Convert the buffer into a string and return it. 
            return new ASCIIEncoding().GetString(fromEncrypt);
        }
        catch(CryptographicException e)
        {
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message);
            return null;
        }
    }
}

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Answer 2

谢谢你的提醒，我试试看。

---

Raymond