[C#] DES 암호화/복호화

C# 에서 문자열을 DES알고림즘을 이용하여 암호화 하거나 복호하 하는
소스를 소개합니다. 

using System; 

using System.Collections.Generic; 

using System.Linq; 

using System.Web; 

using System.Security.Cryptography; 

using System.IO; 

/// <summary&>; 

/// Summary description for Des 

/// </summary&>; 

public class Des 

{ 

    byte[] key = null; 

    protected Des() 

    { 

    } 

    public Des(byte[] desKey) 

    { 

        this.key = desKey; 

    } 

    public string Encrypt(string plain_text) 

    { 

        if (string.IsNullOrEmpty(plain_text)) 

        { 

            throw new ArgumentException("The string which needs to be encrypted can not be null."); 

        } 

        if (key.Length != 8) 

        { 

            throw (new Exception("Invalid key. Key length must be 8 byte.")); 

        } 

        DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider(); 

        MemoryStream memoryStream = new MemoryStream(); 

        CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateEncryptor(key, key), CryptoStreamMode.Write); 

        StreamWriter writer = new StreamWriter(cryptoStream); 

        writer.Write(plain_text); 

        writer.Flush(); 

        cryptoStream.FlushFinalBlock(); 

        writer.Flush(); 

        string cypher_text = Convert.ToBase64String(memoryStream.GetBuffer(), 0, (int)memoryStream.Length); 

        return cypher_text; 

    } 

    public string Decrypt(string cypher_text) 

    { 

        if (String.IsNullOrEmpty(cypher_text)) 

        { 

            throw new ArgumentNullException("The string which needs to be decrypted can not be null."); 

        } 

        if (key.Length != 8) 

        { 

            throw (new Exception("Invalid key. Key length must be 8 byte.")); 

        } 

        DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider(); 

        MemoryStream memoryStream = new MemoryStream(Convert.FromBase64String(cypher_text)); 

        CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateDecryptor(key, key), CryptoStreamMode.Read); 

        StreamReader reader = new StreamReader(cryptoStream); 

        string plain_text = reader.ReadToEnd(); 

        return plain_text; 

    } 

}

사용법 

// 암호화 키(8byte) 

static byte[] desKey = ASCIIEncoding.ASCII.GetBytes("DES키"); 

Des des = new Des(desKey); 

des.Encrypt("암호화할 문장"); 

des.Decrypt("암호풀 문장");