des算法的C#实现

DES是Data Encryption Standard（数据加密标准）的缩写。它是一种通过56位密钥来加密64位数据的方法。

public class EncryptUtility
{
    #region DES
    /// <summary>
    /// DES加密
    /// </summary>
    /// <param name="code">加密字符串</param>
    /// <param name="key">密钥</param>
    /// <returns></returns>
    public static string DesEncrypt(string code, string key)
    {
        string iv = StringUtility.Reverse(key);
        return DesEncrypt(code, key, iv);
    }

    /// <summary>
    /// DES加密
    /// </summary>
    /// <param name="code">加密字符串</param>
    /// <param name="key">密钥</param>
    /// <param name="iv">初始化向量</param>
    /// <returns></returns>
    public static string DesEncrypt(string code, string key, string iv)
    {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        byte[] inputByteArray = Encoding.Default.GetBytes(code);
        des.Key = ASCIIEncoding.ASCII.GetBytes(key);
        des.IV = ASCIIEncoding.ASCII.GetBytes(iv);
        MemoryStream ms = new MemoryStream();
        CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
        cs.Write(inputByteArray, 0, inputByteArray.Length);
        cs.FlushFinalBlock();
        StringBuilder ret = new StringBuilder();
        foreach (byte b in ms.ToArray())
        {
            ret.AppendFormat("{0:X2}", b);
        }
        ms.Dispose();
        cs.Dispose();
        //ret.ToString();
        return ret.ToString();
    }

    /// <summary>
    /// DES解密
    /// </summary>
    /// <param name="code">解密字符串</param>
    /// <param name="key">密钥</param>
    /// <param name="key"></param>
    /// <returns></returns>
    public static string DesDecrypt(string code, string key)
    {
        string iv = StringUtility.Reverse(key);
        return DesDecrypt(code, key, iv);
    }

    /// <summary>
    /// DES解密
    /// </summary>
    /// <param name="code">解密字符串</param>
    /// <param name="key">密钥</param>
    /// <param name="iv">初始化向量</param>
    /// <returns></returns>
    public static string DesDecrypt(string code, string key, string iv)
    {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        byte[] inputByteArray = new byte[code.Length / 2];
        for (int x = 0; x < code.Length / 2; x++)
        {
            int i = (Convert.ToInt32(code.Substring(x * 2, 2), 16));
            inputByteArray[x] = (byte)i;
        }
        des.Key = ASCIIEncoding.ASCII.GetBytes(key);
        des.IV = ASCIIEncoding.ASCII.GetBytes(iv);
        MemoryStream ms = new MemoryStream();
        CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
        cs.Write(inputByteArray, 0, inputByteArray.Length);
        cs.FlushFinalBlock();
        cs.Dispose();
        StringBuilder ret = new StringBuilder();
        return System.Text.Encoding.Default.GetString(ms.ToArray());
    }
    #endregion
}