RealICQClient/Includes/AES/AES.pas

unit AES;

interface
uses
  Windows,SysUtils,Classes,ElAES,math;

function AESDecyptStr(strIn,AESKey: string): string;
function AESEncryptStr(strIn,AESKey: string): string;
implementation
function AESDecyptStr(strIn,AESKey: string): string;
function HexToString(S: string): string;
var
	i: integer;

begin
  Result := '';

  // Go throught every single hexadecimal characters, and convert
  // them to ASCII characters...
  for i := 1 to Length( S ) do
  begin
    // Only process chunk of 2 digit Hexadecimal...
  	if ((i mod 2) = 1) then
	  	Result := Result + Chr( StrToInt( '0x' + Copy( S, i, 2 )));
  end;
end;
var
  Source: TStringStream;
  Dest: TStringStream;
  Start, Stop: cardinal;
  Size: integer;
  Key: TAESKey128;
  EncryptedText: TStrings;
  S: string;

begin
  // Convert hexadecimal to a strings before decrypting...
  Source := TStringStream.Create( HexToString( strIn ));
  Dest   := TStringStream.Create( '' );

  try
    // Start decryption...
    Size := Source.Size;
    Source.ReadBuffer(Size, SizeOf(Size));

    // Prepare key...
    FillChar(Key, SizeOf(Key), 0);
    Move(PChar(AESKey)^, Key, Min(SizeOf(Key), Length(AESKey)));

    // Decrypt now...
    DecryptAESStreamECB(Source, Source.Size - Source.Position, Key, Dest);

    // Display unencrypted text...
    Result := Dest.DataString;

  finally
    Source.Free;
    Dest.Free;
  end;
end;

function AESEncryptStr(strIn,AESKey: string): string;
function StringToHex(S: string): string;
var
	i: integer;

begin
  Result := '';

  // Go throught every single characters, and convert them
  // to hexadecimal...
	for i := 1 to Length( S ) do
  	Result := Result + IntToHex( Ord( S[i] ), 2 );
end;
var
  Source: TStringStream;
  Dest: TStringStream;
  Size: integer;
  Key: TAESKey128;
begin
  // Encryption
  Source := TStringStream.Create(strIn );
  Dest   := TStringStream.Create( '' );

  try
    // Save data to memory stream...
    Size := Source.Size;
    Dest.WriteBuffer( Size, SizeOf(Size) );

    // Prepare key...
    FillChar( Key, SizeOf(Key), 0 );
    Move( PChar(AESKey)^, Key, Min( SizeOf( Key ), Length( AESKey)));

    // Start encryption...
    EncryptAESStreamECB( Source, 0, Key, Dest );

    // Display encrypted text using hexadecimals...
	  Result := StringToHex( Dest.DataString );


  finally
    Source.Free;
    Dest.Free;
  end;
end;
end.