C # encryption and decryption algorithm.

1. method 1 (irreversible encryption) public string EncryptPassword (string PasswordString, string PasswordFormat) {string encryptPassword = null; if (PasswordFormat = "SHA1") {encryptPassword = FormsAuthortication. hashPasswordForStoringInConfigFile (PasswordString, "SHA1");} elseif (PasswordFormat = "MD5") {encryptPassword = FormsAuthortication. hashPasswordForStoringInConfigFile (PasswordString, "MD5");} return encryptPassword;} 2. method 2 (reversible encryption) public interface IBindesh {string encode (string str ); string decode (string str);} public class EncryptionDecryption: IBindesh {public string encode (string str) {string htext = ""; for (int I = 0; I <str. length; I ++) {htext = htext + (char) (str [I] + 10-1*2);} return htext;} public string decode (string str) {string dtext = ""; for (int I = 0; I <str. length; I ++) {dtext = dtext + (char) (str [I]-10 + 1*2);} return dtext;} 3. Method 3 (reversible encryption) const string KEY_64 = "VavicApp"; // note that it is an 8-character, 64-bit const string IV_64 = "VavicApp"; public string Encode (string data) {byte [] byKey = System. text. ASCIIEncoding. ASCII. getBytes (KEY_64); byte [] byIV = System. text. ASCIIEncoding. ASCII. getBytes (IV_64); DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider (); int I = cryptoProvider. keySize; MemoryStream MS = new MemoryStream (); CryptoStream cst = new CryptoStream (MS, cryptoProvider. createEncryptor (byKey, byIV), CryptoStreamMode. write); StreamWriter sw = new StreamWriter (cst); sw. write (data); sw. flush (); cst. flushFinalBlock (); sw. flush (); return Convert. toBase64String (ms. getBuffer (), 0, (int) ms. length);} public string Decode (string data) {byte [] byKey = System. text. ASCIIEncoding. ASCII. getBytes (KEY_64); byte [] byIV = System. text. ASCIIEncoding. ASCII. getBytes (IV_64); byte [] byEnc; try {byEnc = Convert. fromBase64String (data);} catch {return null;} DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider (); MemoryStream MS = new MemoryStream (byEnc); CryptoStream cst = new CryptoStream (MS, cryptoProvider. createDecryptor (byKey, byIV), CryptoStreamMode. read); StreamReader sr = new StreamReader (cst); return sr. readToEnd ();} 4. MD5 irreversible encryption (32-bit encryption) public string GetMD5 (string s, string _ input_charset) {/** // <summary> // MD5 encryption algorithm compatible with ASP /// </summary> MD5 md5 = new MD5CryptoServiceProvider (); byte [] t = md5.ComputeHash (Encoding. getEncoding (_ input_charset ). getBytes (s); StringBuilder sb = new StringBuilder (32); for (int I = 0; I <t. length; I ++) {sb. append (t [I]. toString ("x "). padLeft (2, '0');} return sb. toString () ;}( 16-bit encryption) public static string GetMd5Str (string ConvertString) {MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider (); string t2 = BitConverter. toString (md5.ComputeHash (UTF8Encoding. default. getBytes (ConvertString), 4, 8); t2 = t2.Replace ("-", ""); return t2 ;} 5. encryption of text files // encryption of private static void EncryptData (String inName, String outName, byte [] cipher ey, byte [] desIV) {// Create the file streams to handle the input and output files. fileStream fin = new FileStream (inName, FileMode. open, FileAccess. read); FileStream fout = new FileStream (outName, FileMode. openOrCreate, FileAccess. write); fout. setLength (0); // Create variables to help with read and write. byte [] bin = new byte [100]; // This is intermediate storage for the encryption. long rdlen = 0; // This is the total number of bytes written. long totlen = fin. length; // This is the total length of the input file. int len; // This is the number of bytes to be written at a time. DES des = new DESCryptoServiceProvider (); CryptoStream encStream = new CryptoStream (fout, des. createEncryptor (Cipher ey, desIV), CryptoStreamMode. write); // Read from the input file, then encrypt and write to the output file. while (rdlen <totlen) {len = fin. reads (bin, 0,100); encStream. write (bin, 0, len); rdlen = rdlen + len;} encStream. close (); fout. close (); fin. close () ;}// decrypt the private static void DecryptData (String inName, String outName, byte [] cipher ey, byte [] desIV) File) {// Create the file streams to handle the input and output files. fileStream fin = new FileStream (inName, FileMode. open, FileAccess. read); FileStream fout = new FileStream (outName, FileMode. openOrCreate, FileAccess. write); fout. setLength (0); // Create variables to help with read and write. byte [] bin = new byte [100]; // This is intermediate storage for the encryption. long rdlen = 0; // This is the total number of bytes written. long totlen = fin. length; // This is the total length of the input file. int len; // This is the number of bytes to be written at a time. DES des = new DESCryptoServiceProvider (); CryptoStream encStream = new CryptoStream (fout, des. createDecryptor (Cipher ey, desIV), CryptoStreamMode. write); // Read from the input file, then encrypt and write to the output file. while (rdlen <totlen) {len = fin. reads (bin, 0,100); encStream. write (bin, 0, len); rdlen = rdlen + len;} encStream. close (); fout. close (); fin. close () ;}6, using System; using System. collections. generic; using System. text; using System. security. cryptography; using System. IO; namespace Component {public class Security {public Security () {}// default key vector private static byte [] Keys = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF }; /** // <summary> // DES encrypted string /// </summary> /// <param name = "encryptString"> string to be encrypted </param> /// <param name = "encryptKey"> encryption key, the value must be 8-bit </param> /// <returns>. The encrypted string is returned successfully, and the source string </returns> public static string EncryptDES (string encryptString, string encryptKey) {try {byte [] rgbKey = Encoding. UTF8.GetBytes (encryptKey. substring (0, 8); byte [] rgbIV = Keys; byte [] inputByteArray = Encoding. UTF8.GetBytes (encryptString); DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider (); MemoryStream mStream = new MemoryStream (); CryptoStream cStream = new CryptoStream (mStream, dCSP. createEncryptor (rgbKey, rgbIV), CryptoStreamMode. write); cStream. write (inputByteArray, 0, inputByteArray. length); cStream. flushFinalBlock (); return Convert. toBase64String (mStream. toArray ();} catch {return encryptString ;}} /** // <summary> // decode the string /// </summary> /// <param name = "decryptString"> string to be decrypted </param> /// <param name = "decryptKey"> decrypt the key, the value must be 8 bits. It must be the same as the encryption key. </param> /// <returns> the decrypted string is returned, returned source string failed </returns> public static string DecryptDES (string decryptString, string decryptKey) {try {byte [] rgbKey = Encoding. UTF8.GetBytes (decryptKey); byte [] rgbIV = Keys; byte [] inputByteArray = Convert. fromBase64String (decryptString); DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider (); MemoryStream mStream = new MemoryStream (); CryptoStream cStream = new CryptoStream (mStream, DCSP. createDecryptor (rgbKey, rgbIV), CryptoStreamMode. write); cStream. write (inputByteArray, 0, inputByteArray. length); cStream. flushFinalBlock (); return Encoding. UTF8.GetString (mStream. toArray () ;}catch {return decryptString ;}}}}