Enkripsi dan Deskripsi Password

unit uEncrypt;

interface

function Decrypt(const S: AnsiString; Key: Word): AnsiString;

function Encrypt(const S: AnsiString; Key: Word): AnsiString;

implementation

const

C1 = 52845;

C2 = 22719;

function Decode(const S: AnsiString): AnsiString;

const

Map: array[Char] of Byte = (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53,

54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2,

3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,

20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27, 28, 29, 30,

31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,

46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0);

var

I: LongInt;

begin

case Length(S) of

2:

begin

I := Map[S[1]] + (Map[S[2]] shl 6);

SetLength(Result, 1);

Move(I, Result[1], Length(Result))

end;

3:

begin

I := Map[S[1]] + (Map[S[2]] shl 6) + (Map[S[3]] shl 12);

SetLength(Result, 2);

Move(I, Result[1], Length(Result))

end;

4:

begin

I := Map[S[1]] + (Map[S[2]] shl 6) + (Map[S[3]] shl 12) +

(Map[S[4]] shl 18);

SetLength(Result, 3);

Move(I, Result[1], Length(Result))

end

end

end;

function PreProcess(const S: AnsiString): AnsiString;

var

SS: AnsiString;

begin

SS := S;

Result := '';

while SS <> '' do

begin

Result := Result + Decode(Copy(SS, 1, 4));

Delete(SS, 1, 4)

end

end;

function InternalDecrypt(const S: AnsiString; Key: Word): AnsiString;

var

I: Word;

Seed: Word;

begin

Result := S;

Seed := Key;

for I := 1 to Length(Result) do

begin

Result[I] := Char(Byte(Result[I]) xor (Seed shr 8));

Seed := (Byte(S[I]) + Seed) * Word(C1) + Word(C2)

end

end;

function Decrypt(const S: AnsiString; Key: Word): AnsiString;

begin

Result := InternalDecrypt(PreProcess(S), Key)

end;

function Encode(const S: AnsiString): AnsiString;

const

Map: array[0..63] of Char = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +

'abcdefghijklmnopqrstuvwxyz0123456789+/';

var

I: LongInt;

begin

I := 0;

Move(S[1], I, Length(S));

case Length(S) of

1:

Result := Map[I mod 64] + Map[(I shr 6) mod 64];

2:

Result := Map[I mod 64] + Map[(I shr 6) mod 64] +

Map[(I shr 12) mod 64];

3:

Result := Map[I mod 64] + Map[(I shr 6) mod 64] +

Map[(I shr 12) mod 64] + Map[(I shr 18) mod 64]

end

end;

function PostProcess(const S: AnsiString): AnsiString;

var

SS: AnsiString;

begin

SS := S;

Result := '';

while SS <> '' do

begin

Result := Result + Encode(Copy(SS, 1, 3));

Delete(SS, 1, 3)

end

end;

function InternalEncrypt(const S: AnsiString; Key: Word): AnsiString;

var

I: Word;

Seed: Word;

begin

Result := S;

Seed := Key;

for I := 1 to Length(Result) do

begin

Result[I] := Char(Byte(Result[I]) xor (Seed shr 8));

Seed := (Byte(Result[I]) + Seed) * Word(C1) + Word(C2)

end

end;

function Encrypt(const S: AnsiString; Key: Word): AnsiString;

begin

Result := PostProcess(InternalEncrypt(S, Key))

end;

end.

Sumber : http://www.swissdelphicenter.ch/torry/showcode.php?id=1243