我必须制作客户端服务器应用程序。客户端必须具有上载图像的能力，服务器必须对图像进行简单的操作，然后将图像发送回客户端。通信必须加密。在C＃中最简单的方法是什么？
答案 0 :(得分：0)
有2种不同的东西， 一件事是创建客户端服务器（UDP，TCP套接字）确实很容易，存在很多程序。
第二，使用加密，我已经使用对称键完成了一个示例：
我不知道我在哪里找到此代码，但我显示了它： 对称密钥是客户端和服务器之间的秘密（对不起，我的英语..）
///////////////////////////////////////////////////////////////////////////////
// SAMPLE: Symmetric key encryption and decryption using Rijndael algorithm.
//
// To run this sample, create a new Visual C# project using the Console
// Application template and replace the contents of the Class1.cs file with
// the code below.
//
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
// EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
//
// Copyright (C) 2002-2013 Obviex(TM). All rights reserved.
//
using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;
/// <summary>
/// This class uses a symmetric key algorithm (Rijndael/AES) to encrypt and
/// decrypt data. As long as encryption and decryption routines use the same
/// parameters to generate the keys, the keys are guaranteed to be the same.
/// The class uses static functions with duplicate code to make it easier to
/// demonstrate encryption and decryption logic. In a real-life application,
/// this may not be the most efficient way of handling encryption, so - as
/// soon as you feel comfortable with it - you may want to redesign this class.
/// </summary>
public class RijndaelSimple
{
/// <summary>
/// Encrypts specified plaintext using Rijndael symmetric key algorithm
/// and returns a base64-encoded result.
/// </summary>
/// <param name="plainText">
/// Plaintext value to be encrypted.
/// </param>
/// <param name="passPhrase">
/// Passphrase from which a pseudo-random password will be derived. The
/// derived password will be used to generate the encryption key.
/// Passphrase can be any string. In this example we assume that this
/// passphrase is an ASCII string.
/// </param>
/// <param name="saltValue">
/// Salt value used along with passphrase to generate password. Salt can
/// be any string. In this example we assume that salt is an ASCII string.
/// </param>
/// <param name="hashAlgorithm">
/// Hash algorithm used to generate password. Allowed values are: "MD5" and
/// "SHA1". SHA1 hashes are a bit slower, but more secure than MD5 hashes.
/// </param>
/// <param name="passwordIterations">
/// Number of iterations used to generate password. One or two iterations
/// should be enough.
/// </param>
/// <param name="initVector">
/// Initialization vector (or IV). This value is required to encrypt the
/// first block of plaintext data. For RijndaelManaged class IV must be
/// exactly 16 ASCII characters long.
/// </param>
/// <param name="keySize">
/// Size of encryption key in bits. Allowed values are: 128, 192, and 256.
/// Longer keys are more secure than shorter keys.
/// </param>
/// <returns>
/// Encrypted value formatted as a base64-encoded string.
/// </returns>
public static string Encrypt
(
string plainText,
string passPhrase,
string saltValue,
string hashAlgorithm,
int passwordIterations,
string initVector,
int keySize
)
{
// Convert strings into byte arrays.
// Let us assume that strings only contain ASCII codes.
// If strings include Unicode characters, use Unicode, UTF7, or UTF8
// encoding.
byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
byte[] saltValueBytes = Encoding.ASCII.GetBytes(saltValue);
// Convert our plaintext into a byte array.
// Let us assume that plaintext contains UTF8-encoded characters.
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
// First, we must create a password, from which the key will be derived.
// This password will be generated from the specified passphrase and
// salt value. The password will be created using the specified hash
// algorithm. Password creation can be done in several iterations.
PasswordDeriveBytes password = new PasswordDeriveBytes
(
passPhrase,
saltValueBytes,
hashAlgorithm,
passwordIterations
);
// Use the password to generate pseudo-random bytes for the encryption
// key. Specify the size of the key in bytes (instead of bits).
byte[] keyBytes = password.GetBytes(keySize / 8);
// Create uninitialized Rijndael encryption object.
RijndaelManaged symmetricKey = new RijndaelManaged();
// It is reasonable to set encryption mode to Cipher Block Chaining
// (CBC). Use default options for other symmetric key parameters.
symmetricKey.Mode = CipherMode.CBC;
// Generate encryptor from the existing key bytes and initialization
// vector. Key size will be defined based on the number of the key
// bytes.
ICryptoTransform encryptor = symmetricKey.CreateEncryptor
(
keyBytes,
initVectorBytes
);
// Define memory stream which will be used to hold encrypted data.
MemoryStream memoryStream = new MemoryStream();
// Define cryptographic stream (always use Write mode for encryption).
CryptoStream cryptoStream = new CryptoStream
(
memoryStream,
encryptor,
CryptoStreamMode.Write
);
// Start encrypting.
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
// Finish encrypting.
cryptoStream.FlushFinalBlock();
// Convert our encrypted data from a memory stream into a byte array.
byte[] cipherTextBytes = memoryStream.ToArray();
// Close both streams.
memoryStream.Close();
cryptoStream.Close();
// Convert encrypted data into a base64-encoded string.
string cipherText = Convert.ToBase64String(cipherTextBytes);
// Return encrypted string.
return cipherText;
}
/// <summary>
/// Decrypts specified ciphertext using Rijndael symmetric key algorithm.
/// </summary>
/// <param name="cipherText">
/// Base64-formatted ciphertext value.
/// </param>
/// <param name="passPhrase">
/// Passphrase from which a pseudo-random password will be derived. The
/// derived password will be used to generate the encryption key.
/// Passphrase can be any string. In this example we assume that this
/// passphrase is an ASCII string.
/// </param>
/// <param name="saltValue">
/// Salt value used along with passphrase to generate password. Salt can
/// be any string. In this example we assume that salt is an ASCII string.
/// </param>
/// <param name="hashAlgorithm">
/// Hash algorithm used to generate password. Allowed values are: "MD5" and
/// "SHA1". SHA1 hashes are a bit slower, but more secure than MD5 hashes.
/// </param>
/// <param name="passwordIterations">
/// Number of iterations used to generate password. One or two iterations
/// should be enough.
/// </param>
/// <param name="initVector">
/// Initialization vector (or IV). This value is required to encrypt the
/// first block of plaintext data. For RijndaelManaged class IV must be
/// exactly 16 ASCII characters long.
/// </param>
/// <param name="keySize">
/// Size of encryption key in bits. Allowed values are: 128, 192, and 256.
/// Longer keys are more secure than shorter keys.
/// </param>
/// <returns>
/// Decrypted string value.
/// </returns>
/// <remarks>
/// Most of the logic in this function is similar to the Encrypt
/// logic. In order for decryption to work, all parameters of this function
/// - except cipherText value - must match the corresponding parameters of
/// the Encrypt function which was called to generate the
/// ciphertext.
/// </remarks>
public static string Decrypt
(
string cipherText,
string passPhrase,
string saltValue,
string hashAlgorithm,
int passwordIterations,
string initVector,
int keySize
)
{
// Convert strings defining encryption key characteristics into byte
// arrays. Let us assume that strings only contain ASCII codes.
// If strings include Unicode characters, use Unicode, UTF7, or UTF8
// encoding.
byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
byte[] saltValueBytes = Encoding.ASCII.GetBytes(saltValue);
// Convert our ciphertext into a byte array.
byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
// First, we must create a password, from which the key will be
// derived. This password will be generated from the specified
// passphrase and salt value. The password will be created using
// the specified hash algorithm. Password creation can be done in
// several iterations.
PasswordDeriveBytes password = new PasswordDeriveBytes
(
passPhrase,
saltValueBytes,
hashAlgorithm,
passwordIterations
);
// Use the password to generate pseudo-random bytes for the encryption
// key. Specify the size of the key in bytes (instead of bits).
byte[] keyBytes = password.GetBytes(keySize / 8);
// Create uninitialized Rijndael encryption object.
RijndaelManaged symmetricKey = new RijndaelManaged();
// It is reasonable to set encryption mode to Cipher Block Chaining
// (CBC). Use default options for other symmetric key parameters.
symmetricKey.Mode = CipherMode.CBC;
// Generate decryptor from the existing key bytes and initialization
// vector. Key size will be defined based on the number of the key
// bytes.
ICryptoTransform decryptor = symmetricKey.CreateDecryptor
(
keyBytes,
initVectorBytes
);
// Define memory stream which will be used to hold encrypted data.
MemoryStream memoryStream = new MemoryStream(cipherTextBytes);
// Define cryptographic stream (always use Read mode for encryption).
CryptoStream cryptoStream = new CryptoStream
(
memoryStream,
decryptor,
CryptoStreamMode.Read
);
// Since at this point we don't know what the size of decrypted data
// will be, allocate the buffer long enough to hold ciphertext;
// plaintext is never longer than ciphertext.
byte[] plainTextBytes = new byte[cipherTextBytes.Length];
// Start decrypting.
int decryptedByteCount = cryptoStream.Read
(
plainTextBytes,
0,
plainTextBytes.Length
);
// Close both streams.
memoryStream.Close();
cryptoStream.Close();
// Convert decrypted data into a string.
// Let us assume that the original plaintext string was UTF8-encoded.
string plainText = Encoding.UTF8.GetString
(
plainTextBytes,
0,
decryptedByteCount
);
// Return decrypted string.
return plainText;
}
}
使用示例：
/// <summary>
/// Illustrates the use of RijndaelSimple class to encrypt and decrypt data.
/// </summary>
public class RijndaelSimpleTest
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
string plainText = "Hello, World!"; // original plaintext
string passPhrase = "Kes0pr@se"; // can be any string
string saltValue = "V@1tValue"; // can be any string
string hashAlgorithm = "SHA1"; // can be "MD5"
int passwordIterations= 3; // can be any number
string initVector = "@1B2c3D4e5F6g7H8"; // must be 16 bytes
int keySize = 256; // can be 192 or 128
Console.WriteLine(String.Format("Plaintext : {0}", plainText));
string cipherText = RijndaelSimple.Encrypt
(
plainText,
passPhrase,
saltValue,
hashAlgorithm,
passwordIterations,
initVector,
keySize
);
Console.WriteLine(String.Format("Encrypted : {0}", cipherText));
plainText = RijndaelSimple.Decrypt
(
cipherText,
passPhrase,
saltValue,
hashAlgorithm,
passwordIterations,
initVector,
keySize
);
Console.WriteLine(String.Format("Decrypted : {0}", plainText));
}
}
//
// END OF FILE
客户端和服务器都知道不同的设置（密码，密钥...），您可以在连接开始时定义将正确的设置发送到服务器的方式