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Кодирование и раскодирование паролей
Кодирование и раскодирование паролей

// This example shows how you can encrypt strings 
// using special security string.
// You can decode data only if you know security string.
// I suppose, there is no chance to hack security string, using any analyse algorythms.
// Every time you call this function, you will
// have a new result even if all params are constant
// NOTE: Don`t forget to call "Randomize" proc before using this functions.

const
Codes64 = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/';

// you must use this function to generate special
// security string, which is used in main encode/decode routines.
// NOTE: you must generate the security string only once and then use it in encode/decode functions.

function GeneratePWDSecutityString: string;
var
i, x: integer;
s1, s2: string;
begin
s1 := Codes64;
s2 := '';
for i := 0 to 15 do
begin
x := Random(Length(s1));
x := Length(s1) - x;
s2 := s2 + s1[x];
s1 := Copy(s1, 1,x - 1) + Copy(s1, x + 1,Length(s1));
end;
Result := s2;
end;

// this function generate random string using
// any characters from "CHARS" string and length
// of "COUNT" - it will be used in encode routine
// to add "noise" into your encoded data.

function MakeRNDString(Chars: string; Count: Integer): string;
var
i, x: integer;
begin
Result := '';
for i := 0 to Count - 1 do
begin
x := Length(chars) - Random(Length(chars));
Result := Result + chars[x];
chars := Copy(chars, 1,x - 1) + Copy(chars, x + 1,Length(chars));
end;
end;


// This will encode your data.
// "SecurityString" must be generated using method
// described above, and then stored anywhere to
// use it in Decode function.
// "Data" is your string (you can use any characters here)
// "MinV" - minimum quantity of "noise" chars before each encoded data char.
// "MaxV" - maximum quantity of "noise" chars before each encoded data char.

function EncodePWDEx(Data, SecurityString: string; MinV: Integer = 0;
MaxV: Integer = 5): string;
var
i, x: integer;
s1, s2, ss: string;
begin
if minV > MaxV then
begin
i := minv;
minv := maxv;
maxv := i;
end;
if MinV < 0 then MinV := 0;
if MaxV > 100 then MaxV := 100;
Result := '';
if Length(SecurityString) < 16 then Exit;
for i := 1 to Length(SecurityString) do
begin
s1 := Copy(SecurityString, i + 1,Length(securitystring));
if Pos(SecurityString[i], s1) > 0 then Exit;
if Pos(SecurityString[i], Codes64) <= 0 then Exit;
end;
s1 := Codes64;
s2 := '';
for i := 1 to Length(SecurityString) do
begin
x := Pos(SecurityString[i], s1);
if x > 0 then s1 := Copy(s1, 1,x - 1) + Copy(s1, x + 1,Length(s1));
end;
ss := securitystring;
for i := 1 to Length(Data) do
begin
s2 := s2 + ss[Ord(Data[i]) mod 16 + 1];
ss := Copy(ss, Length(ss), 1) + Copy(ss, 1,Length(ss) - 1);
s2 := s2 + ss[Ord(Data[i]) div 16 + 1];
ss := Copy(ss, Length(ss), 1) + Copy(ss, 1,Length(ss) - 1);
end;
Result := MakeRNDString(s1, Random(MaxV - MinV) + minV + 1);
for i := 1 to Length(s2) do Result := Result + s2[i] + MakeRNDString(s1,
Random(MaxV - MinV) + minV);
end;

// This will decode your data, encoded with the function above, using specified "SecurityString".

function DecodePWDEx(Data, SecurityString: string): string;
var
i, x, x2: integer;
s1, s2, ss: string;
begin
Result := #1;
if Length(SecurityString) < 16 then Exit;
for i := 1 to Length(SecurityString) do
begin
s1 := Copy(SecurityString, i + 1,Length(securitystring));
if Pos(SecurityString[i], s1) > 0 then Exit;
if Pos(SecurityString[i], Codes64) <= 0 then Exit;
end;
s1 := Codes64;
s2 := '';
ss := securitystring;
for i := 1 to Length(Data) do if Pos(Data[i], ss) > 0 then s2 := s2 + Data[i];
Data := s2;
s2 := '';
if Length(Data) mod 2 <> 0 then Exit;
for i := 0 to Length(Data) div 2 - 1 do
begin
x := Pos(Data[i * 2 + 1], ss) - 1;
if x < 0 then Exit;
ss := Copy(ss, Length(ss), 1) + Copy(ss, 1,Length(ss) - 1);
x2 := Pos(Data[i * 2 + 2], ss) - 1;
if x2 < 0 then Exit;
x := x + x2 * 16;
s2 := s2 + chr(x);
ss := Copy(ss, Length(ss), 1) + Copy(ss, 1,Length(ss) - 1);
end;
Result := s2;
end;

Категория: Статьи Delphi | Добавил: c1 (2009 Июль 10)
Просмотров: 731 | Теги: Кодирование и раскодирование пароле | Рейтинг: 0.0/0

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