The cryptographic encode and decryption decode of ASP.

The encryption and decryption of ASP (C #):

1. Import the required packages:

Using System.IO;

Using System.Text;

Using System.Security.Cryptography;

2. Encryption

1) MD5 General encryption

Get the field to encrypt and convert to byte[] Array

byte[] data = System.Text.Encoding.Unicode. GetBytes (str. ToCharArray ());

Establishing Cryptographic Services

System.Security.Cryptography.MD5 MD5 = new System.Security.Cryptography.MD5CryptoServiceProvider ();

Encrypt byte[] Array

Byte[] result = Md5.computehash (data);

Response.Write ("MD5 normal encryption:" + System.Text.Encoding.Unicode.GetString (result));

2) MD5 password encryption [common]

Response.Write ("MD5 Password encryption:" + System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile (str, "MD5" ));

3) ASP. How to encrypt and decrypt querystring in net [frequently used]

Encryption

Response.Redirect ("detailinfo.aspx?id=" + convert.tobase64string (System.Text.Encoding.Default.GetBytes (str)). Replace ("+", "%2b"));

Decrypt

String id = System.Text.Encoding.Default.GetString (convert.frombase64string (request.querystring["id"). ToString (). Replace ("%2b", "+"));

Encryption and decryption functions:

Protected Function Encode (ByVal thestr As String) as String

Return convert.tobase64string (System.Text.Encoding.Default.GetBytes (THESTR)). Replace ("+", "%2b")
End Function
Protected Function Decode (ByVal thestr As String) as String
Return System.Text.Encoding.Default.GetString (convert.frombase64string (Thestr.replace ("%2b", "+"))
End Function

4) DES encryption and decryption algorithm [common key algorithm]

public static string key = "DKMAB5DE";//encryption key must be 8 bits

Encryption algorithm

public static string Md5encrypt (String ptoencrypt)

{DESCryptoServiceProvider des = new DESCryptoServiceProvider ();

byte[] Inputbytearray = Encoding.Default.GetBytes (Ptoencrypt);

Des. Key = ASCIIEncoding.ASCII.GetBytes (key);

DES.IV = ASCIIEncoding.ASCII.GetBytes (Key);

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);

}

Ret. ToString ();

return ret. ToString ();

}

Decryption algorithm

public static string Md5decrypt (String ptodecrypt)

{DESCryptoServiceProvider des = new DESCryptoServiceProvider ();

byte[] Inputbytearray = new BYTE[PTODECRYPT.LENGTH/2];

for (int x = 0; x < PTODECRYPT.LENGTH/2; × x + +) {

int i = (Convert.ToInt32 (ptodecrypt.substring (x * 2, 2), 16));

INPUTBYTEARRAY[X] = (byte) i;

}

Des. Key = ASCIIEncoding.ASCII.GetBytes (key);

DES.IV = ASCIIEncoding.ASCII.GetBytes (Key);

MemoryStream ms = new MemoryStream ();

CryptoStream cs = new CryptoStream (MS, Des. CreateDecryptor (), cryptostreammode.write);

Cs. Write (Inputbytearray, 0, inputbytearray.length);

Cs. FlushFinalBlock ();

StringBuilder ret = new StringBuilder ();

Return System.Text.Encoding.ASCII.GetString (Ms. ToArray ());

}

5) RSA encryption and decryption algorithm [common key algorithm]

Encryption algorithm

public string Rsaencrypt (string encryptstring)

{CspParameters CSP = new CspParameters ();

Csp. KeyContainerName = "Whaben";

RSACryptoServiceProvider Rsaprovider = new RSACryptoServiceProvider (CSP);

byte[] encryptbytes = Rsaprovider.encrypt (ASCIIEncoding.ASCII.GetBytes (encryptstring), true);

String str = "";

foreach (Byte b in encryptbytes)

{str = str + string. Format ("{0:x2}", b);

}

return str;

}

Decryption algorithm

public string Rsadecrypt (string decryptstring)

{CspParameters CSP = new CspParameters ();

Csp. KeyContainerName = "Whaben";

RSACryptoServiceProvider Rsaprovider = new RSACryptoServiceProvider (CSP);

int length = (DECRYPTSTRING.LENGTH/2);

byte[] decryptbytes = new Byte[length];

for (int index = 0; index < length; index++)

{String substring = decryptstring.substring (Index * 2, 2);

Decryptbytes[index] = convert.tobyte (substring, 16);

}

Decryptbytes = Rsaprovider.decrypt (Decryptbytes, true);

Return ASCIIEncoding.ASCII.GetString (decryptbytes);

}