library RSA;

{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }

uses
  SysUtils,
  Classes,
  FGInt in 'FGInt.pas',
  FGIntPrimeGeneration in 'FGIntPrimeGeneration.PAS',
  FGIntRSA in 'FGIntRSA.PAS',
  ranlib in 'ranlib.pas';

{$R *.res}
//------------------------------------------------------------------------------
procedure GetDNE(var KeyD: PChar; KeyDMaxCount: Integer;
                 var KeyN: PChar; KeyNMaxCount: Integer;
                 var KeyE: PChar; KeyEMaxCount: Integer); stdcall;
var
  Seed,
  iLoop,
  S1, S2: integer;

  n, e, d, dp, dq, p, q, phi, one, two, gcd, temp, nilgint,te1,te2,te3 : TFGInt;
  e1, d1, n1: string;
begin
  //生成随机数
  Seed := Round(Time()*3600000.0);

  WRandomInit(seed);

  for iLoop := 1 to 20 do
  begin
    WRandom();
    WIRandom(0,1000);
  end;
  
  S1 := WIRandom(0,1000000000);
  S2 := WIRandom(0,1000000000);

   //生成密钥
   Base10StringToFGInt(IntToStr(S1), p);
   PrimeSearch(p);//产生质数
   Base256StringToFGInt(IntToStr(S2), q);//对可视字符解码，使之成为数字
   PrimeSearch(q);//产生质数

   FGIntMul(p, q, n);//作p*q=n

   p.Number[1] := p.Number[1] - 1; //把p的最后一位减1
   q.Number[1] := q.Number[1] - 1;

   FGIntMul(p, q, phi); //作(p-1)*(q-1)=phi
   
   //找出与phi（就是(p-1)*(q-1)）互质的数（r）
   Base10StringToFGInt('65537', e); 
   Base10StringToFGInt('1', one);
   Base10StringToFGInt('2', two);
   FGIntGCD(phi, e, gcd);       //检验是否互质的函数,如果PHI和E互质，GCD等于1
   While FGIntCompareAbs(gcd, one) <> Eq Do     //寻找互质数
   Begin
      FGIntadd(e, two, temp);  //每次循环加2
      FGIntCopy(temp, e);
      FGIntGCD(phi, e, gcd);
   End;

   FGIntDestroy(two);
   FGIntDestroy(one);
   FGIntDestroy(gcd);

   FGIntModInv(e, phi, d);
   FGIntModInv(e, p, dp);
   FGIntModInv(e, q, dq);
   p.Number[1] := p.Number[1] + 1;
   q.Number[1] := q.Number[1] + 1;
   Base10StringToFGInt('100', te1);
   Base10StringToFGInt('25', te2);
   FGIntMul(te1, te2, te3);

   FGIntToBase10String(e, e1);
   StrCopy(KeyE, PChar(e1));

   FGIntToBase10String(d, d1);
   StrCopy(KeyD, PChar(d1));

   FGIntToBase10String(n, n1);
   StrCopy(KeyN, PChar(n1));

   FGIntDestroy(phi);
   FGIntDestroy(nilgint);
   FGIntDestroy(p);
   FGIntDestroy(q);
   FGIntDestroy(dp);
   FGIntDestroy(dq);
   FGIntDestroy(e);
   FGIntDestroy(d);
   FGIntDestroy(n);
end;

//------------------------------------------------------------------------------
//E,N为公钥
function RealICQRSAEncrypt(P: PChar; KeyE, KeyN: PChar): PChar; stdcall;
var
  strResult,
  strSource: String;

  e, n: TFGInt;
begin
  strResult := '';
  try
    strSource := P;
    
    Base10StringToFGInt(KeyE, e);
    Base10StringToFGInt(KeyN, n);
    
    RSAEncrypt(strSource, e, n, strSource);

    ConvertBase256to64(strSource, strResult);

    FGIntDestroy(e);
    FGIntDestroy(n);
  finally
    Result := PChar(strResult);
  end;
end;

//------------------------------------------------------------------------------
//D,N为私钥
function RealICQRSADecrypt(E: PChar; KeyD, KeyN: PChar): PChar; stdcall;
var
  strResult,
  strSource: String;

  d,n,nilgint:TFGInt;
begin
  strResult := E;
  try
    ConvertBase64to256(strResult, strSource);
    strResult := '';
    Base10StringToFGInt(KeyD, d);
    Base10StringToFGInt(KeyN, n);
    RSADecrypt(strSource, d, n, Nilgint, Nilgint, Nilgint, Nilgint, strResult);

    FGIntDestroy(d);
    FGIntDestroy(n);
    FGIntDestroy(nilgint);
  finally
    Result := PChar(strResult);
  end;
end;

exports
  GetDNE, RealICQRSAEncrypt, RealICQRSADecrypt;

begin
  IsMultiThread := TRUE; 
end.