C# 加解密算法

算法介绍

3DES又称Triple DES，是DES加密算法的一种模式，它使用3条56位的密钥对
数据进行三次加密。数据加密标准（DES）是美国的一种由来已久的加密标准，它使用对称密钥加密法，并于1981年被ANSI组织规范为ANSI X.3.92。DES使用56位密钥和密码块的方法，而在密码块的方法中，文本被分成64位大小的文本块然后再进行加密。比起最初的DES，3DES更为安全。

3DES（即Triple DES）是DES向AES过渡的加密算法（1999年，NIST将3-DES指定为过渡的加密标准），加密算法，其具体实现如下：设Ek()和Dk()代表DES算法的加密和解密过程，K代表DES算法使用的密钥，P代表明文，C代表密文，这样：

3DES加密过程为：C=Ek3(Dk2(Ek1(P)))
3DES解密过程为：P=Dk1(EK2(Dk3(C)))

DES加解密

key 是八位长的字符串

#region Des 加解密

public static string DesEncrypt(string encryptStr, string key)
{
try
{
var inputArry = Encoding.Default.GetBytes(encryptStr);
var byKey = Encoding.ASCII.GetBytes(key);
var byIv = Encoding.ASCII.GetBytes(key);
var ms = new MemoryStream();
using (var cryptoProvider = new DESCryptoServiceProvider())
{
using (var cs = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIv), CryptoStreamMode.Write))
{
cs.Write(inputArry, 0, inputArry.Length);
cs.FlushFinalBlock();
cs.Close();
}
}

var str = Convert.ToBase64String(ms.ToArray());
ms.Close();
return str;
}
catch (Exception)
{
return encryptStr;
}

}

public static string DesDecrypt(string decryptStr, string key)
{
try
{
var inputArry = Convert.FromBase64String(decryptStr);
var byKey = Encoding.Default.GetBytes(key);
var byIv = Encoding.Default.GetBytes(key);
var ms = new MemoryStream();
using (var cryptProvider = new DESCryptoServiceProvider())
{
using (var cs = new CryptoStream(ms, cryptProvider.CreateDecryptor(byKey, byIv), CryptoStreamMode.Write))
{
cs.Write(inputArry, 0, inputArry.Length);
cs.FlushFinalBlock();
cs.Close();
}
}

var str = Encoding.Default.GetString(ms.ToArray());
ms.Close();
return str;
}
catch (Exception)
{
return decryptStr;
}

}

#endregion

3Des加解密

#region 3DES 加解密

public static string Encrypt3Des(string encryStr, string key)
{
try
{
var inputArry = Encoding.Default.GetBytes(encryStr);
var hashmd5 = new MD5CryptoServiceProvider();
var byKey = hashmd5.ComputeHash(Encoding.Default.GetBytes(key));
var byIv = byKey;
var ms = new MemoryStream();
using (var tDescryptProvider = new TripleDESCryptoServiceProvider())
{
tDescryptProvider.Mode = CipherMode.ECB;
using (var cs = new CryptoStream(ms, tDescryptProvider.CreateEncryptor(byKey, byIv), CryptoStreamMode.Write))
{
cs.Write(inputArry, 0, inputArry.Length);
cs.FlushFinalBlock();
cs.Close();
}
}

var str = Convert.ToBase64String(ms.ToArray());
ms.Close();
return str;
}
catch (Exception)
{
return encryStr;
}

}

public static string Decrypt3Des(string decryStr, string key)
{
try
{
var inputArry = Convert.FromBase64String(decryStr);
var hashmd5 = new MD5CryptoServiceProvider();
var byKey = hashmd5.ComputeHash(Encoding.Default.GetBytes(key));
var byIv = byKey;
var ms = new MemoryStream();
using (var tDescryptProvider = new TripleDESCryptoServiceProvider())
{
tDescryptProvider.Mode = CipherMode.ECB;
using (var cs = new CryptoStream(ms, tDescryptProvider.CreateDecryptor(byKey, byIv), CryptoStreamMode.Write))
{
cs.Write(inputArry, 0, inputArry.Length);
cs.FlushFinalBlock();
cs.Close();
}
}

var str = Encoding.Default.GetString(ms.ToArray());
ms.Close();
return str;
}
catch (Exception)
{
return decryStr;
}
}

#endregion