using System;
using System.Runtime.InteropServices;
using System.Xml;
using System.Reflection;


namespace DJD.Security
{
	[Guid("2929CA28-4CA5-4f61-AC5E-B5FF7BADADEC"), ClassInterface(ClassInterfaceType.AutoDual)]
	public class keyParams
		
	{
		public keyParams(){}
		static BigInteger _N,_E,_D;

		public BigInteger N
		{
			get{return _N;}

			set{_N = value;}
		
		}
		public BigInteger E
		{
			get{return _E;}

			set{_E = value;}
		
		}
		public BigInteger D
		{
			get{return _D;}

			set{_D = value;}
		
		}

		
	}

	// algorithm taken from http://pajhome.org.uk/crypt/rsa/index.html 8/03 by Dom DiNatale
	// Java implementation adapted to C# from http://www.geocities.com/wailian/QuickStartRSA/
	// Also got some help from http://www.codeproject.com/csharp/biginteger.asp
	[Guid("BEA6B48A-A477-45a6-AA82-5DE407FF2502"), ClassInterface(ClassInterfaceType.AutoDual)]
	public sealed class Encryption : IDisposable
		
	{
		private keyParams _key = new keyParams();

		public Encryption(){}
		public Encryption(int bitSize)
		{
			if (!((bitSize == 8) | (bitSize == 16) | (bitSize == 32) | (bitSize == 64) | (bitSize == 128) | (bitSize == 256) | (bitSize == 512))){throw new  ArgumentException("Encryption supports only 8, 16, 32, 64, 128, 256, 512 bit encryption");};

			BigInteger q;
			BigInteger p;
			BigInteger m;
			
			p = BigInteger.genPseudoPrime(bitSize,10,new System.Random());

			do
			{
				q = BigInteger.genPseudoPrime(bitSize,10, new System.Random());
			}
			while(p == q);
				
			_key.N = (p*q);
			m = (p-1)*(q-1);
						
			_key.E = new BigInteger("10001", 16);
			_key.D = _key.E.modInverse(m);


		}


		public void GenerateKeys(int bitSize)
		{
			Encryption obj = new Encryption(bitSize);
			this._key = obj.ExportParamaters(true);
			obj.Dispose();
			obj = null;
		}
		
		public string Decrypt( BigInteger[] encrypted )
		{
			if (_key.D == 0) {throw new ApplicationException("Invalid key");};
			int i ;


			BigInteger[] decrypted = new BigInteger[encrypted.Length] ;
			
			for( i = 0 ; i < decrypted.Length ; i++ )
				
				decrypted[i] = encrypted[i].modPow((_key.D),(_key.N)) ;

			char[] charArray = new char[decrypted.Length] ;

			for( i = 0 ; i < charArray.Length ; i++ )
				charArray[i] = (char) ( (byte)decrypted[i].IntValue() ) ;

			return( new string( charArray ) ) ;
		} 

		public BigInteger[] Encrypt(string message )
		{
			if ((_key.E == 0) || (_key.N == 0)) {throw new ApplicationException("Invalid Key");};
			int i ;
			byte[] temp = new byte[1] ;

			byte[] digits = System.Text.ASCIIEncoding.ASCII.GetBytes(message);

			BigInteger[] bigdigits = new BigInteger[digits.Length] ;

			for( i = 0 ; i < bigdigits.Length ; i++ )
			{
				temp[0] = digits[i] ;
				bigdigits[i] = new BigInteger( temp ) ;
			}

			BigInteger[] encrypted = new BigInteger[bigdigits.Length] ;

			for( i = 0 ; i < bigdigits.Length ; i++ )
				encrypted[i] = bigdigits[i].modPow( _key.E,_key.N) ;


			return( encrypted ) ;
		} 

		
		public void Dispose()
		{
			GC.SuppressFinalize(this);
		}
								 
		public keyParams ExportParamaters(bool includePrivateParams)
		{
			keyParams pKey = _key;

			if (!includePrivateParams)
			{
				pKey.D = 0;
			}
			return pKey;
		}

		public string ExportParamatersAsXML(bool includePrivateParams)
		{

			keyParams pKey = _key;

			if (!includePrivateParams)
			{
				pKey.D = 0;
			}


			
			string str = "<key><N>" + System.Convert.ToBase64String(pKey.N.getBytes()) + "</N><E>" + System.Convert.ToBase64String(pKey.E.getBytes()) + "</E><D>" + System.Convert.ToBase64String(pKey.D.getBytes()) + "</D></key>";
			return str;
		}

		public void ExportParamatersToFile(bool includePrivateParams, string FilePath)
		{
			System.IO.FileInfo fl = new System.IO.FileInfo(FilePath);
			System.IO.FileStream fs = fl.OpenWrite();
			string str = ExportParamatersAsXML(includePrivateParams);
			byte[] b = new byte[str.Length];
			b = System.Text.ASCIIEncoding.ASCII.GetBytes(str);
			fs.Write(b,0,b.Length);
			fs.Close();
			fs = null;
			fl = null;
		
		}

		public void ImportKeyParameters(keyParams key)
		{
			
			_key.D = key.D;
			_key.E = key.E;
			_key.N = key.N;
			
		}
		public string ImportKeyParameters(System.IO.FileInfo keyFile)
		{
			keyParams pKey = new keyParams();
			XmlTextReader reader = new XmlTextReader(keyFile.FullName);
			while (reader.Read())
			{
				if (reader.NodeType == XmlNodeType.Element)
				{
					if (reader.Name == "N")
					{
						reader.Read();
						byte[] b = Convert.FromBase64String(reader.Value);
						pKey.N = new BigInteger(b);
					}
					if (reader.Name == "E")
					{
						reader.Read();
						byte[] b = Convert.FromBase64String(reader.Value);
						pKey.E = new BigInteger(b);
					}
					if (reader.Name == "D")
					{
						reader.Read();
						byte[] b = Convert.FromBase64String(reader.Value);
						pKey.D = new BigInteger(b);
					}
				}	
			};
			_key = pKey;
			return "";
		}

		//		public string ImportKeyParameters(string strXML)
		//		{
		//			keyParams pKey = new keyParams();
		//
		//			string strN = "";
		//			string strE = "";
		//			string strD = "";
		//
		//			int i, j;
		//			i = strXML.IndexOf("<N>");
		//			j = strXML.IndexOf("</N>");
		//			strN = Mid(str,i,j-i);
		//			
		//			i = strXML.IndexOf("<E>");
		//			j = strXML.IndexOf("</E>");
		//			strE = Mid(str,i,j-i);
		//			
		//			i = strXML.IndexOf("<D>");
		//			j = strXML.IndexOf("</D>");
		//			strD = Mid(str,i,j-i);
		//
		//			byte[] b;
		//
		//			b = Convert.FromBase64String(strN);
		//			pKey.N = new BigInteger(b);
		//					
		//			b = Convert.FromBase64String(strE);
		//			pKey.E = new BigInteger(b);
		//
		//			b = Convert.FromBase64String(strD);
		//			pKey.D = new BigInteger(b);
		//
		//			_key = pKey;
		//			return "";
		//		}
		
		public string GetJavaScriptClientCode()
		{
			System.IO.Stream st = GetType().Assembly.GetManifestResourceStream("DJD.Security.BigInt.js");
			byte[] b = new byte[st.Length];
			st.Read(b,0,(int)st.Length);
			st.Close();

			string strBigInt = System.Text.ASCIIEncoding.ASCII.GetString(b);

			

			return  
				"<script language=JavaScript>\n" +
				strBigInt +
				"\n\n" +
				"// To use the encrypt function, use an onclick or onsubmit event of a button to encrypt a textbox's value property.\n" +
				"// The following example puts the value of the encrypted password into a hidden input and makes the password text *'s the length of the original password.\n" +
				"// <INPUT type=" + (char)34 + "submit" + (char)34 + " value=" + (char)34 + "Login" + (char)34 + " OnClick=" + (char)34 + "var s = txtPassword.value; password.value=Encrypt(s,'<%=Session(" + (char)34 + "n" + (char)34 + ")%>','<%=Session(" + (char)34 + "e" + (char)34 + ")%>'); var strStar = ''; for (i = 0; i < s.length; i++) {strStar = strStar + '*';}  txtPassword.value = strStar" + (char)34 + "><input id=" + (char)34 + "password" + (char)34 + " type=" + (char)34 + "hidden" + (char)34 + " name=" + (char)34 + "password" + (char)34 + ">\n" +
				"function Encrypt (str, n, e) {\n" +
				"	var n=str2bigInt(n,16,0);\n" +
				"	var x=str2bigInt(str,95,n.length);\n" +
				"	var y=str2bigInt(e,16,0);\n" +
				"	powMod(x,y,n,0);\n" +
				"	x = bigInt2str(x,16);\n" +
				"	return x;\n" +
				"}\n" +		
				"</script>\n";
		}
		
		

	
        
	}
}