DES 加密 解密

public static class Common
{
/// <summary>
/// 密钥
/// </summary>
public static string key = "@#$!";

#region 解密
/// <summary>
/// 解密
/// </summary>
/// <param name="str"></param>
/// <param name="key"></param>
/// <returns></returns>
public static string Decode(string str, string key)
{
string sss = "";
byte[] keyBytes = Encoding.Unicode.GetBytes(key);
byte[] inputByteArray = Convert.FromBase64String(str);
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
MemoryStream mStream = new MemoryStream();
CryptoStream cStream = new CryptoStream(mStream, provider.CreateDecryptor(keyBytes, keyBytes), CryptoStreamMode.Write);
cStream.Write(inputByteArray, 0, inputByteArray.Length);
cStream.FlushFinalBlock();
sss = Encoding.Unicode.GetString(mStream.ToArray()); //Unicode编码
return sss;
}

#endregion

#region 加密
/// <summary>
/// 加密
/// </summary>
/// <param name="str"></param>
/// <param name="key"></param>
/// <returns></returns>
public static string Encode(string str, string key)
{
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
byte[] btKey = Encoding.Unicode.GetBytes(key); //向量   密钥
byte[] buffer = Encoding.Unicode.GetBytes(str); //Unicode编码
MemoryStream stream = new MemoryStream();
CryptoStream stream2 = new CryptoStream(stream, provider.CreateEncryptor(btKey, btKey), CryptoStreamMode.Write);
stream2.Write(buffer, 0, buffer.Length);
stream2.FlushFinalBlock();
return Convert.ToBase64String(stream.ToArray());
}
#endregion

#region
public static string GetSubString(string string_0, int int_0, string string_1)
{
return GetSubString(string_0, 0, int_0, string_1);
}

public static string GetSubString(string string_0, int int_0, int int_1, string string_1)
{
string str = string_0;
byte[] bytes = Encoding.UTF8.GetBytes(string_0);
foreach (char ch in Encoding.UTF8.GetChars(bytes))
{
if (((ch > 'ࠀ') && (ch < '一')) || ((ch > 0xac00) && (ch < 0xd7a3)))
{
if (int_0 < string_0.Length)
{
return string_0.Substring(int_0, ((int_1 + int_0) > string_0.Length) ? (string_0.Length - int_0) : int_1);
}
return "";
}
}
if (int_1 < 0)
{
return str;
}
byte[] sourceArray = Encoding.Default.GetBytes(string_0);
if (sourceArray.Length <= int_0)
{
return str;
}
int length = sourceArray.Length;
if (sourceArray.Length <= (int_0 + int_1))
{
int_1 = sourceArray.Length - int_0;
string_1 = "";
}
else
{
length = int_1 + int_0;
}
int num2 = int_1;
int[] numArray = new int[int_1];
byte[] destinationArray = null;
int num3 = 0;
for (int i = int_0; i < length; i++)
{
if (sourceArray[i] > 0x7f)
{
num3++;
if (num3 == 3)
{
num3 = 1;
}
}
else
{
num3 = 0;
}
numArray[i] = num3;
}
if ((sourceArray[length - 1] > 0x7f) && (numArray[int_1 - 1] == 1))
{
num2 = int_1 + 1;
}
destinationArray = new byte[num2];
Array.Copy(sourceArray, int_0, destinationArray, 0, num2);
return (Encoding.Default.GetString(destinationArray) + string_1);
}

#endregion
}