Delphi 버전 RC4 암호화 알고리즘

{===============================================================================

    :    Rc4_StrEncrypt()
     :    RC4 Based string encryption
     :   i_Encrypt ——  1    , 0    （integer  ）；
           s_EncryptText ——   （  ）    （string  ）；
           s_EncryptPassword ——  （  ）   （string  ）；
           i_EncryptLevel ——    （  ：1－－10；integer  ））

   :           
 QQ:           93331961
=============================================================================== }
unit Rc4_Unit;

interface
uses
   SysUtils;

   function Rc4_StrEncrypt(i_Encrypt:integer; s_EncryptText,
      s_EncryptPassword:string; i_EncryptLevel:integer = 1):string;
      
implementation

function Rc4_StrEncrypt(i_Encrypt:integer; s_EncryptText,
  s_EncryptPassword:string; i_EncryptLevel:integer = 1):string;
var
  v_EncryptModified, v_EncryptCipher, v_EncryptCipherBy:string;
  i_EncryptCountA, i_EncryptCountB, i_EncryptCountC, i_EncryptCountD,
    i_EncryptCountE, i_EncryptCountF, i_EncryptCountG, i_EncryptCountH,
    v_EncryptSwap:integer;
  av_EncryptBox:array[0..256, 0..2] of integer;

begin
  if (i_Encrypt <> 0) and (i_Encrypt <> 1) then
  begin
    result := '';
  end
  else if (s_EncryptText = '') or (s_EncryptPassword = '') then
  begin
    result := '';
  end
  else
  begin
    if (i_EncryptLevel <= 0) or (Int(i_EncryptLevel) <> i_EncryptLevel) then
      i_EncryptLevel := 1;
    if Int(i_EncryptLevel) > 10 then i_EncryptLevel := 10;
    if i_Encrypt = 1 then
    begin
      for i_EncryptCountF := 0 to i_EncryptLevel do
      begin
        i_EncryptCountG := 0;
        i_EncryptCountH := 0;
        v_EncryptModified := '';
        for i_EncryptCountG := 1 to Length(s_EncryptText) do
        begin
          if i_EncryptCountH = Length(s_EncryptPassword) then
          begin
            i_EncryptCountH := 1;
          end
          else
          begin
            inc(i_EncryptCountH);
          end;
          v_EncryptModified := v_EncryptModified +
            Chr(Ord(s_EncryptText[i_EncryptCountG]) xor
            Ord(s_EncryptPassword[i_EncryptCountH]) xor 255);
        end;
        s_EncryptText := v_EncryptModified;
        i_EncryptCountA := 0;
        i_EncryptCountB := 0;
        i_EncryptCountC := 0;
        i_EncryptCountD := 0;
        i_EncryptCountE := 0;
        v_EncryptCipherBy := '';
        v_EncryptCipher := '';
        v_EncryptSwap := 0;
        for i_EncryptCountA := 0 to 255 do
        begin
          av_EncryptBox[i_EncryptCountA, 1] :=
            Ord(s_EncryptPassword[i_EncryptCountA mod Length(s_EncryptPassword) +
            1]);
          av_EncryptBox[i_EncryptCountA, 0] := i_EncryptCountA;
        end;
        for i_EncryptCountA := 0 to 255 do
        begin
          i_EncryptCountB := (i_EncryptCountB + av_EncryptBox[i_EncryptCountA][0]
            + av_EncryptBox[i_EncryptCountA][1]) mod 256;
          v_EncryptSwap := av_EncryptBox[i_EncryptCountA][0];
          av_EncryptBox[i_EncryptCountA][0] :=
            av_EncryptBox[i_EncryptCountB][0];
          av_EncryptBox[i_EncryptCountB][0] := v_EncryptSwap;
        end;
        for i_EncryptCountA := 1 to Length(s_EncryptText) do
        begin
          i_EncryptCountC := (i_EncryptCountC + 1) mod 256;
          i_EncryptCountD := (i_EncryptCountD +
            av_EncryptBox[i_EncryptCountC][0]) mod 256;
          i_EncryptCountE := av_EncryptBox[(av_EncryptBox[i_EncryptCountC][0] +
            av_EncryptBox[i_EncryptCountD][0]) mod 256][0];
          v_EncryptCipherBy := inttostr(Ord(s_EncryptText[i_EncryptCountA]) xor
            i_EncryptCountE);
          v_EncryptCipher := v_EncryptCipher +
            IntToHex(strtoint(v_EncryptCipherBy), 2);

        end;
        s_EncryptText := v_EncryptCipher;
      end;

    end
    else
    begin
      for i_EncryptCountF := 0 to i_EncryptLevel do
      begin
        i_EncryptCountB := 0;
        i_EncryptCountC := 0;
        i_EncryptCountD := 0;
        i_EncryptCountE := 0;
        v_EncryptCipherBy := '';
        v_EncryptCipher := '';
        v_EncryptSwap := 0;
        for i_EncryptCountA := 0 to 255 do
        begin
          av_EncryptBox[i_EncryptCountA, 1] :=
            Ord(s_EncryptPassword[i_EncryptCountA mod Length(s_EncryptPassword) +
            1]);
          av_EncryptBox[i_EncryptCountA, 0] := i_EncryptCountA;
        end;
        for i_EncryptCountA := 0 to 255 do
        begin
          i_EncryptCountB := (i_EncryptCountB + av_EncryptBox[i_EncryptCountA, 0]
            + av_EncryptBox[i_EncryptCountA, 1]) mod 256;
          v_EncryptSwap := av_EncryptBox[i_EncryptCountA, 0];
          av_EncryptBox[i_EncryptCountA, 0] := av_EncryptBox[i_EncryptCountB,
            0];
          av_EncryptBox[i_EncryptCountB, 0] := v_EncryptSwap;
        end;
        for i_EncryptCountA := 1 to Length(s_EncryptText) do
        begin
          if (i_EncryptCountA mod 2) <> 0 then
          begin
            i_EncryptCountC := ((i_EncryptCountC + 1) mod 256);
            i_EncryptCountD := ((i_EncryptCountD +
              av_EncryptBox[i_EncryptCountC, 0]) mod 256);
            i_EncryptCountE := av_EncryptBox[((av_EncryptBox[i_EncryptCountC, 0]
              + av_EncryptBox[i_EncryptCountD, 0]) mod 256), 0];
            v_EncryptCipherBy := inttostr(StrToInt64('$' +
              s_EncryptText[i_EncryptCountA] + s_EncryptText[i_EncryptCountA + 1])
              xor i_EncryptCountE);
            v_EncryptCipher := v_EncryptCipher +
              Chr(strtoint(v_EncryptCipherBy));
          end;
        end;
        s_EncryptText := v_EncryptCipher;
        i_EncryptCountG := 0;
        i_EncryptCountH := 0;
        v_EncryptModified := '';
        for i_EncryptCountG := 1 to Length(s_EncryptText) do
        begin
          if i_EncryptCountH = Length(s_EncryptPassword) then
          begin
            i_EncryptCountH := 1;
          end
          else
          begin
            i_EncryptCountH := i_EncryptCountH + 1;
          end;
          v_EncryptModified := v_EncryptModified +
            Chr((Ord(s_EncryptText[i_EncryptCountG]) xor
            Ord(s_EncryptPassword[i_EncryptCountH]) xor 255));
        end;
        s_EncryptText := v_EncryptModified;
      end;
    end;
    result := s_EncryptText;
  end;
end;

end.