unit EncryptIt;
interface
USES
Classes;
const
C1 = 52845;
C2 = 22719;
function Encrypt(const S: String; Key: Word): String;
function Decrypt(const S: String; Key: Word): String;
procedure EncryptFile(INFName, OutFName : String; Key : Word);
procedure DecryptFile(INFName, OutFName : String; Key : Word);
implementation
function Encrypt(const S: String; Key: Word): String;
var
I: Integer;
begin
Result := S;
for I := 1 to Length(S) do
begin
Result := char(byte(S) xor (Key shr 8));
Key := (byte(Result) + Key) * C1 + C2;
end;
end;
function Decrypt(const S: String; Key: Word): String;
var
I: Integer;
begin
Result := S;
for I := 1 to Length(S) do
begin
Result := char(byte(S) xor (Key shr 8));
Key := (byte(S) + Key) * C1 + C2;
end;
end;
procedure EncryptFile(INFName, OutFName : String; Key : Word);
VAR
MS, SS : TMemoryStream;
X : Integer;
C : Byte;
begin
MS := TMemoryStream.Create;
SS := TMemoryStream.Create;
TRY
MS.LoadFromFile(INFName);
MS.Position := 0;
FOR X := 0 TO MS.Size - 1 DO
begin
MS.Read(C, 1);
C := (C xor (Key shr 8));
Key := (C + Key) * C1 + C2;
SS.Write(C,1);
end;
SS.SaveToFile(OutFName);
FINALLY
SS.Free;
MS.Free;
end;
end;
procedure DecryptFile(INFName, OutFName : String; Key : Word);
VAR
MS, SS : TMemoryStream;
X : Integer;
C, O : Byte;
begin
MS := TMemoryStream.Create;
SS := TMemoryStream.Create;
TRY
MS.LoadFromFile(INFName);
MS.Position := 0;
FOR X := 0 TO MS.Size - 1 DO
begin
MS.Read(C, 1);
O := C;
C := (C xor (Key shr 8));
Key := (O + Key) * C1 + C2;
SS.Write(C,1);
end;
SS.SaveToFile(OutFName);
FINALLY
SS.Free;
MS.Free;
end;
end;
end.
