Delphi RC4 Encryption Source Code
Post date: Mar 13, 2010 5:21:52 PM
{
Unit: uRC4 // RC4 Encryption
Author: Andreas J”nsson
Original: freevbcode.com/ShowCode.asp?ID=4398
Ported by: steve10120
Website: hackhound.org
}
This unit should be used in place of TheRogue's unit, since there existed a bug in:
Result := Result + ...
because the result was never nulled. This wouldn't be a problem with a byte array - which is used in this unit.
unit uRC4;
interface
uses Windows;
function RC4(Expression, Password:string):string;
type
TByteArray = array of Byte;
implementation
procedure Move(Destination, Source: Pointer; dLength:Cardinal);
begin
CopyMemory(Destination, Source, dLength);
end;
function RC4(Expression, Password:string):string;
var
RB: array[0..255] of integer;
X, Y, Z: LongInt;
Key: TByteArray;
ByteArray: TByteArray;
Temp: Byte;
begin
if Length(Password) = 0 then
Exit;
if Length(Expression) = 0 then
Exit;
if Length(Password) > 256 then
begin
SetLength(Key, 256);
Move(@Key[0], @Password[1], 256)
end
else
begin
SetLength(Key, Length(Password));
Move(@Key[0], @Password[1], Length(Password));
end;
for X := 0 to 255 do
RB[X] := X;
X := 0;
Y := 0;
Z := 0;
for X := 0 to 255 do
begin
Y := (Y + RB[X] + Key[X mod Length(Password)]) mod 256;
Temp := RB[X];
RB[X] := RB[Y];
RB[Y] := Temp;
end;
X := 0;
Y := 0;
Z := 0;
SetLength(ByteArray, Length(Expression));
Move(@ByteArray[0], @Expression[1], Length(Expression));
for X := 0 to Length(Expression) - 1 do
begin
Y := (Y + 1) mod 256;
Z := (Z + RB[Y]) mod 256;
Temp := RB[Y];
RB[Y] := RB[Z];
RB[Z] := Temp;
ByteArray[X] := ByteArray[X] xor (RB[(RB[Y] + RB[Z]) mod 256]);
end;
SetLength(Result, Length(Expression));
Move(@Result[1], @ByteArray[0], Length(Expression));
end;
end.