{$I-,R-}

Unit Crypter;

interface
Uses Objects;

procedure EnCrypt(var Pntr: Array of Char; ArrLen: Word; password: string);
{ - Закpиптовать блок }
procedure DeCrypt(var Pntr: Array of Char; ArrLen: Word; password: string);
{ - Раскиптовать блок }

procedure EnCryptStream(var st: tStream; Password: String);
{ - Закpиптовать поток }
procedure DeCryptStream(var st: tStream; Password: String);
{ - Раскиптовать поток }

implementation

procedure EnCrypt(var Pntr: Array of Char; ArrLen:Word; password: string);
var
 len,pcounter: byte;
 x:Word;
begin
 len := length(password) div 2;
 pcounter := 1;
 for x:=0 to ArrLen-1 do begin
 Pntr[x] := chr(ord(password[pcounter]) + ord(Pntr[x]) + len);
 inc(pcounter);
 if pcounter > length(password) then pcounter := 1;
 end;
end;

procedure DeCrypt(var Pntr: Array of Char; ArrLen:Word; password: string);
var
 len,pcounter: byte;
 x:Word;
begin
 len := length(password) div 2;
 pcounter := 1;
 for x:=0 to ArrLen-1 do begin
 Pntr[x] := chr(ord(Pntr[x]) - ord(password[pcounter]) - len);
 inc(pcounter);
 if pcounter > length(password) then pcounter := 1;
 end;
end;

type
 pBuffer = ^tBuffer;
 tBuffer = Array[1..$FFFF] of Char;

procedure EnCryptStream(var st: tStream; Password: String);
 var
 buf: pBuffer;
 StSize, StPos, p: Longint;
 begin
 if (@st=nil) or (Password='') then exit;
 New(buf);
 StPos:=st.GetPos;
 StSize:=st.GetSize;
 st.Reset;
 st.Seek(0);
 repeat
 p:=st.GetPos;
 if SizeOf(Buf^)> St.GetSize-St.GetPosthen st.Read(buf^,St.GetSize-St.GetPos)
else st.Read(buf^,SizeOf(Buf^));
 EnCrypt(buf^,SizeOf(buf^),password);
 st.Reset;
 st.Seek(p);
 st.Write(buf^,SizeOf(Buf^));
 until (St.GetSize=St.GetPos);
 st.Seek(StSize);
 st.Truncate;
 st.Seek(StPos);
 Dispose(buf);
 end;

procedure DeCryptStream(var st: tStream; Password: String);
 var
 buf: pBuffer;
 StSize, StPos, p: Longint;
 begin
 if (@st=nil) or (Password='') then exit;
 New(buf);
 StPos:=st.GetPos;
 StSize:=st.GetSize;
 st.Reset;
 st.Seek(0);
 repeat
 p:=st.GetPos;
 if SizeOf(Buf^)> St.GetSize-St.GetPosthen st.Read(buf^,St.GetSize-St.GetPos)
else st.Read(buf^,SizeOf(Buf^));
 DeCrypt(buf^,SizeOf(buf^),password);
 st.Reset;
 st.Seek(p);
 st.Write(buf^,SizeOf(Buf^));
 until (St.GetSize=St.GetPos);
 st.Seek(StSize);
 st.Truncate;
 st.Seek(StPos);
 Dispose(buf);
 end;

end.