www.pudn.com > boogiebot.zip > RC4.cs

using System; 
using System.Text; 
 
/** 
 * RC4 Class 
 * @package RC4.NET 
 */ 
namespace Foole.Crypt 
{ 
    public class RC4 
    { /* inherits Page for ASP.NET */ 
        /** 
         * Get ASCII Integer Code 
         * 
         * @param char ch Character to get ASCII value for 
         * @access private 
         * @return int 
         */ 
        private static int ord(char ch) 
        { 
            return (int)(Encoding.GetEncoding(1252).GetBytes(ch + "")[0]); 
        } 
        /** 
         * Get character representation of ASCII Code 
         * 
         * @param int i ASCII code 
         * @access private 
         * @return char 
         */ 
        private static char chr(int i) 
        { 
            byte[] bytes = new byte[1]; 
            bytes[0] = (byte)i; 
            return Encoding.GetEncoding(1252).GetString(bytes)[0]; 
        } 
        /** 
         * Convert Hex to Binary (hex2bin) 
         * 
         * @param string packtype Rudimentary in this implementation 
         * @param string datastring Hex to be packed into Binary 
         * @access private 
         * @return string 
         */ 
        private static string pack(string packtype, string datastring) 
        { 
            int i, j, datalength, packsize; 
            byte[] bytes; 
            char[] hex; 
            string tmp; 
 
            datalength = datastring.Length; 
            packsize = (datalength / 2) + (datalength % 2); 
            bytes = new byte[packsize]; 
            hex = new char[2]; 
 
            for (i = j = 0; i < datalength; i += 2) 
            { 
                hex[0] = datastring[i]; 
                if (datalength - i == 1) 
                    hex[1] = '0'; 
                else 
                    hex[1] = datastring[i + 1]; 
                tmp = new string(hex, 0, 2); 
                try { bytes[j++] = byte.Parse(tmp, System.Globalization.NumberStyles.HexNumber); } 
                catch { } /* grin */ 
            } 
            return Encoding.GetEncoding(1252).GetString(bytes); 
        } 
        /** 
         * Convert Binary to Hex (bin2hex) 
         * 
         * @param string bindata Binary data 
         * @access public 
         * @return string 
         */ 
        public static string bin2hex(string bindata) 
        { 
            int i; 
            byte[] bytes = Encoding.GetEncoding(1252).GetBytes(bindata); 
            string hexString = ""; 
            for (i = 0; i < bytes.Length; i++) 
            { 
                hexString += bytes[i].ToString("x2"); 
            } 
            return hexString; 
        } 
        /** 
         * The symmetric encryption function 
         * 
         * @param string pwd Key to encrypt with (can be binary of hex) 
         * @param string data Content to be encrypted 
         * @param bool ispwdHex Key passed is in hexadecimal or not 
         * @access public 
         * @return string 
         */ 
        public static string Encrypt(string pwd, string data, bool ispwdHex) 
        { 
            int a, i, j, k, tmp, pwd_length, data_length; 
            int[] key, box; 
            byte[] cipher; 
            //string cipher; 
 
            if (ispwdHex) 
                pwd = pack("H*", pwd); // valid input, please! 
            pwd_length = pwd.Length; 
            data_length = data.Length; 
            key = new int[256]; 
            box = new int[256]; 
            cipher = new byte[data.Length]; 
            //cipher = ""; 
 
            for (i = 0; i < 256; i++) 
            { 
                key[i] = ord(pwd[i % pwd_length]); 
                box[i] = i; 
            } 
            for (j = i = 0; i < 256; i++) 
            { 
                j = (j + box[i] + key[i]) % 256; 
                tmp = box[i]; 
                box[i] = box[j]; 
                box[j] = tmp; 
            } 
            for (a = j = i = 0; i < data_length; i++) 
            { 
                a = (a + 1) % 256; 
                j = (j + box[a]) % 256; 
                tmp = box[a]; 
                box[a] = box[j]; 
                box[j] = tmp; 
                k = box[((box[a] + box[j]) % 256)]; 
                cipher[i] = (byte)(ord(data[i]) ^ k); 
                //cipher += chr(ord(data[i]) ^ k); 
            } 
            return Encoding.GetEncoding(1252).GetString(cipher); 
            //return cipher; 
        } 
        /** 
         * Decryption, recall encryption 
         * 
         * @param string pwd Key to decrypt with (can be binary of hex) 
         * @param string data Content to be decrypted 
         * @param bool ispwdHex Key passed is in hexadecimal or not 
         * @access public 
         * @return string 
         */ 
        public static string Decrypt(string pwd, string data, bool ispwdHex) 
        { 
            return Encrypt(pwd, data, ispwdHex); 
        } 
    } 
}