Class of the commonly used cryptographic strings, transferred from Osleague Ah, author: bigeagle

Encryption | string using System;
Using System.Security;
Using System.Security.Cryptography;
Using System.Diagnostics;
Using System.Web;
Using System.Text;

Namespace Bigeagle.util
{
<summary>
An encryption class
<br>Author:Bigeagle@163.net</br>
<br>Date:2001/09/25</br>
&LT;BR&GT;HISTORY:2001/10/25 finished</br>
</summary>
<remarks>
Encapsulation of commonly used encryption algorithms
</remarks>
public Class cryptography
{

<summary>
MD5 encrypt the specified string
</summary>
<param name= "A_strvalue" > string to encrypt </param>
<returns> the encrypted string </returns>
public static string Encryptmd5string (String a_strvalue)
{
#if DEBUG
Debug.Assert (A_strvalue.trim ()!= "", "empty string", "empty string does not need encryption");
#endif//debug

Convert into ByteArray
Byte[] HBA = ((HashAlgorithm) cryptoconfig.createfromname ("MD5")).
ComputeHash (Stringtobytearray (A_strvalue));

Return bytearraytostring (HBA);
}

<summary>
Determine if two encrypted strings are the same
</summary>
<param name= "A_STR1" ></param>
<param name= "A_STR2" ></param>
<returns> if the same return true </returns>
public static bool Issame (string a_str1, String a_str2)
{
Byte[] B1 = Stringtobytearray (A_STR1);
byte[] B2 = Stringtobytearray (A_STR2);
if (B1. Length!= B2. Length)
{
return false;
}

for (int i = 0; I < B1. Length; i + +)
{
if (B1[i]!= b2[i])
{
return false;
}
}

return true;
}

<summary>
Convert string to Byte tree Group
</summary>
<param name= "S" > string to be converted </param>
<returns> conversion of byte array </returns>
public static byte[] Stringtobytearray (String s)
{
/*
char[] CA = S.tochararray ();
byte[] ba = new BYTE[CA. Length];
for (int i=0; i<ba. Length; i++) Ba[i] = (Byte) ca[i];
Return ba;*/

return Encoding.UTF8.GetBytes (s);
}

<summary>
Convert byte array to string
</summary>
<param name= "a_arrbyte" >byte array </param>
<returns> string </returns>
public static string ByteArrayToString (byte[] a_arrbyte)
{
/*
char[] CA = new Char[a_arrbyte.length];
for (int i = 0; i < a_arrbyte.length i + +)
{
Result + = (char) a_arrbyte[i];
}*/

Return Encoding.UTF8.GetString (A_arrbyte);
}


<summary>
3DES encrypted string
</summary>
<param name= "A_strstring" > string to encrypt </param>
<param name= "A_strkey" > Key </param>
<returns> encoded string </returns> after encryption and base64
<remarks> static method, using default ASCII encoding </remarks>
public static string Encrypt3des (String a_strstring, String a_strkey)
{
TripleDESCryptoServiceProvider DES = new
TripleDESCryptoServiceProvider ();
MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider ();

Des. Key = Hashmd5.computehash (ASCIIEncoding.ASCII.GetBytes (A_strkey));
Des. Mode = CIPHERMODE.ECB;

ICryptoTransform desencrypt = DES. CreateEncryptor ();

byte[] Buffer = ASCIIEncoding.ASCII.GetBytes (a_strstring);
Return Convert.tobase64string (Desencrypt.transformfinalblock
(Buffer, 0, buffer.length));
}//end method

<summary>
3DES encrypted string
</summary>
<param name= "A_strstring" > string to encrypt </param>
<param name= "A_strkey" > Key </param>
<param name= "encoding" > Coding mode </param>
<returns> encoded string </returns> after encryption and base63
<remarks> overload, specifying the encoding method </remarks>
public static string Encrypt3des (String a_strstring, String a_strkey, Encoding Encoding)
{
TripleDESCryptoServiceProvider DES = new
TripleDESCryptoServiceProvider ();
MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider ();

Des. Key = Hashmd5.computehash (encoding. GetBytes (A_strkey));
Des. Mode = CIPHERMODE.ECB;

ICryptoTransform desencrypt = DES. CreateEncryptor ();

byte[] Buffer = encoding. GetBytes (a_strstring);
Return Convert.tobase64string (Desencrypt.transformfinalblock
(Buffer, 0, buffer.length));
}


<summary>
3DES decryption string
</summary>
<param name= "A_strstring" > String to Decrypt </param>
<param name= "A_strkey" > Key </param>
<returns> after decryption of the string </returns>
<exception cref= "" > Key error </exception>
<remarks> static method, using default ASCII encoding </remarks>
public static string Decrypt3des (String a_strstring, String a_strkey)
{
TripleDESCryptoServiceProvider DES = new
TripleDESCryptoServiceProvider ();
MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider ();

Des. Key = Hashmd5.computehash (ASCIIEncoding.ASCII.GetBytes (A_strkey));
Des. Mode = CIPHERMODE.ECB;

ICryptoTransform desdecrypt = DES. CreateDecryptor ();

string result = "";
Try
{
byte[] Buffer = convert.frombase64string (a_strstring);
result = ASCIIEncoding.ASCII.GetString (desdecrypt.transformfinalblock
(Buffer, 0, buffer.length));
}
catch (Exception e)
{
#if DEBUG
Console.WriteLine ("Error: {0}", e);
#endif//debug
Throw (New Exception ("Invalid Key or input string is not a valid Base64 string", E));
}

return result;
}//end method

<summary>
3DES decryption string
</summary>
<param name= "A_strstring" > String to Decrypt </param>
<param name= "A_strkey" > Key </param>
<param name= "encoding" > Coding mode </param>
<returns> after decryption of the string </returns>
<exception cref= "" > Key error </exception>
<remarks> static method, specifying encoding method </remarks>
public static string Decrypt3des (String a_strstring, String a_strkey, Encoding Encoding)
{
TripleDESCryptoServiceProvider DES = new
TripleDESCryptoServiceProvider ();
MD5CryptoServiceProvider hashMD5 = new MD5CryptoServiceProvider ();

Des. Key = Hashmd5.computehash (encoding. GetBytes (A_strkey));
Des. Mode = CIPHERMODE.ECB;

ICryptoTransform desdecrypt = DES. CreateDecryptor ();

string result = "";
Try
{
byte[] Buffer = convert.frombase64string (a_strstring);
result = Encoding. GetString (Desdecrypt.transformfinalblock
(Buffer, 0, buffer.length));
}
catch (Exception e)
{
#if DEBUG
Console.WriteLine ("Error: {0}", e);
#endif//debug
Throw (New Exception ("Invalid Key or input string is not a valid Base64 string", E));
}

return result;
}//end method


}
}