Asp.Net C#中除了MD5加密之外还经常用到了AES加密、解密与DES加密、解密，本次先介绍DES的加密及解密。注意的是DES的密匙是8位的。

private static readonly String strDesKey = "imaoblog";//加密所需8位密匙

/// <summary>
/// DES加密
/// </summary>
/// <param name="str">要加密字符串</param>
/// <returns>返回加密后字符串</returns>
public static String Encrypt_DES(String str)
{
    System.Security.Cryptography.DESCryptoServiceProvider des = new System.Security.Cryptography.DESCryptoServiceProvider();

Byte[] inputByteArray = System.Text.Encoding.Default.GetBytes(str);
    des.Key = System.Text.ASCIIEncoding.ASCII.GetBytes(strDesKey);
    des.IV = System.Text.ASCIIEncoding.ASCII.GetBytes(strDesKey);
    System.IO.MemoryStream ms = new System.IO.MemoryStream();
    System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, des.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write);
    cs.Write(inputByteArray, 0, inputByteArray.Length);
    cs.FlushFinalBlock();

System.Text.StringBuilder sb = new System.Text.StringBuilder();
    foreach (Byte b in ms.ToArray())
        sb.AppendFormat("{0:X2}", b);

return sb.ToString();
}

/// <summary>
/// DES解密
/// </summary>
/// <param name="str">要解密字符串</param>
/// <returns>返回解密后字符串</returns>
public static String Decrypt_DES(String str)
{
    System.Security.Cryptography.DESCryptoServiceProvider des = new System.Security.Cryptography.DESCryptoServiceProvider();
    Int32 x;
    Byte[] inputByteArray = new Byte[str.Length / 2];
    for (x = 0; x < str.Length / 2; x++)
        inputByteArray[x] = (Byte)(Convert.ToInt32(str.Substring(x * 2, 2), 16));

des.Key = System.Text.ASCIIEncoding.ASCII.GetBytes(strDesKey);
    des.IV = System.Text.ASCIIEncoding.ASCII.GetBytes(strDesKey);
    System.IO.MemoryStream ms = new System.IO.MemoryStream();
    System.Security.Cryptography.CryptoStream cs = new System.Security.Cryptography.CryptoStream(ms, des.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Write);

cs.Write(inputByteArray, 0, inputByteArray.Length);
    cs.FlushFinalBlock();

System.Text.StringBuilder ret = new System.Text.StringBuilder();

return System.Text.Encoding.Default.GetString(ms.ToArray());
}

Asp.Net C#续上次的DES加密、解密之后，再发一个AES的加密、解密。AES要注意的是32位密匙。

private static readonly String strAesKey = "iwww.maoblog.comiwww.maoblog.com";//加密所需32位密匙

/// <summary>
/// AES加密
/// </summary>
/// <param name="str">要加密字符串</param>
/// <returns>返回加密后字符串</returns>
public static String Encrypt_AES(String str)
{
    Byte[] keyArray = System.Text.UTF8Encoding.UTF8.GetBytes(strAesKey);
    Byte[] toEncryptArray = System.Text.UTF8Encoding.UTF8.GetBytes(str);

System.Security.Cryptography.RijndaelManaged rDel = new System.Security.Cryptography.RijndaelManaged();
    rDel.Key = keyArray;
    rDel.Mode = System.Security.Cryptography.CipherMode.ECB;
    rDel.Padding = System.Security.Cryptography.PaddingMode.PKCS7;

System.Security.Cryptography.ICryptoTransform cTransform = rDel.CreateEncryptor();
    Byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}

/// <summary>
/// AES解密
/// </summary>
/// <param name="str">要解密字符串</param>
/// <returns>返回解密后字符串</returns>
public static String Decrypt_AES(String str)
{
    Byte[] keyArray = System.Text.UTF8Encoding.UTF8.GetBytes(strAesKey);
    Byte[] toEncryptArray = Convert.FromBase64String(str);

System.Security.Cryptography.RijndaelManaged rDel = new System.Security.Cryptography.RijndaelManaged();
    rDel.Key = keyArray;
    rDel.Mode = System.Security.Cryptography.CipherMode.ECB;
    rDel.Padding = System.Security.Cryptography.PaddingMode.PKCS7;

System.Security.Cryptography.ICryptoTransform cTransform = rDel.CreateDecryptor();
    Byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

return System.Text.UTF8Encoding.UTF8.GetString(resultArray);
}

本文转载自大奇异果的博客：http://www.cnblogs.com/kiwifruit/archive/2010/10/28/1863141.html