Hi

__history/uRSA.pas.~1~

@@ -0,0 +1,274 @@
+unit uRSA;
+
+interface
+
+uses
+  uBigNum, uHash;
+
+const
+  RSA_GEN_P = 0;
+  RSA_GEN_Q = 1;
+
+type
+  THashMethod = ( hmMD5, hmSHA1 );
+
+type
+  TRSACallback = TBigNumCallback;
+
+  TRSA = class
+  private
+    FD, FE, FN: TBigNum;
+    FCallback: TBigNumCallback;
+    FUserData: Integer;
+    FState: Integer;
+    FHashMethod: THashMethod;
+  public
+    constructor Create;
+    destructor Destroy; override;
+
+    property D: TBigNum read FD;
+    property E: TBigNum read FE;
+    property N: TBigNum read FN;
+    property HashMethod: THashMethod read FHashMethod write FHashMethod;
+
+    procedure SavePrivateKey(FileName: string);
+    procedure LoadPrivateKey(FileName: string);
+
+    procedure SavePublicKey(FileName: string);
+    procedure LoadPublicKey(FileName: string);
+
+    function RandomKey(Bits: Integer; E: TDigit; Callback: TRSACallback;
+        UserData: Integer): Boolean;
+    function GenerateKey(const P, Q: TBigNum; E: TDigit): Boolean;
+
+    function Sign(const Buffer; Length: Integer; var Sig; var SigLen: Integer): Boolean;
+    function Verify(const Buffer; Length: Integer; const Sig; SigLen: Integer): Boolean;
+
+    procedure Encrypt(N: TBigNum);
+    procedure Decrypt(N: TBigNum);
+  end;
+
+implementation
+
+function BigNumCallback(State, Data, UserData: Integer): Boolean;
+var
+  RSA: TRSA;
+begin
+  Result := True;  
+  RSA := TRSA(UserData);
+  if Assigned(RSA.FCallback) then
+  begin
+    if not RSA.FCallback(RSA.FState, Data, RSA.FUserData) then
+      Result := False;
+  end;
+end;
+
+constructor TRSA.Create;
+begin
+  FD := TBigNum.Create;
+  FE := TBigNum.Create;
+  FN := TBigNum.Create;
+end;
+
+destructor TRSA.Destroy;
+begin
+  FD.Free;
+  FN.Free;
+  FE.Free;
+end;
+
+function TRSA.RandomKey(Bits: Integer; E: TDigit; Callback: TBigNumCallback;
+    UserData: Integer): Boolean;
+var
+  p, q: TBigNum;
+begin
+  Result := False;
+
+  FCallback := Callback;
+  FUserData := UserData;
+
+  p := TBigNum.Create;
+  q := TBigNum.Create;
+  try
+    repeat
+      repeat
+        FState := RSA_GEN_P;
+        if not p.RandomPrime(Bits shr 1, 5, BigNumCallback, Integer(Self)) then
+          Exit;
+
+        FState := RSA_GEN_Q;
+        if not q.RandomPrime(Bits shr 1, 5, BigNumCallback, Integer(Self)) then
+          Exit;
+      until p.Compare(q) <> 0;
+    until GenerateKey(p, q, E);
+    Result := True;
+  finally
+    p.Free;
+    q.Free;
+  end;
+end;
+
+function TRSA.GenerateKey(const P, Q: TBigNum; E: TDigit): Boolean;
+var
+  A, B: TBigNum;
+begin
+  A := P.Clone;
+  B := Q.Clone;
+
+  FN.Copy(A);
+  FN.Mul(B);
+
+  A.Sub(1);
+  B.Sub(1);
+  A.Mul(B);
+
+  FE.CopyDigit(E);
+  FD.CopyDigit(E);
+  Result := FD.ModInv(A) and not FD.Sign;
+
+  A.Free;
+  B.Free;
+end;
+
+function TRSA.Sign(const Buffer; Length: Integer; var Sig; var SigLen: Integer): Boolean;
+var
+  Hash: THash;
+  Digest: TDigest;
+  N: TBigNum;
+  I: Integer;
+begin
+  Result := False;
+
+  if FHashMethod = hmMD5 then
+    Hash := TMD5.Create
+  else { FHashMethod = hmSHA1 }
+    Hash := TSHA1.Create;
+
+  if SigLen < Hash.Digest.Length then
+    Exit;
+
+  Digest := Hash.Hash(Buffer, Length);
+  SigLen := Digest.Length;
+  N := TBigNum.CreateBytes(Digest.Buffer, Digest.Length);
+  N.Mod_(FN);
+  Decrypt(N);
+
+  for I := 0 to N.Count - 1 do
+    TDigitArray(Sig)[I] := N.Digit[I];
+
+  Hash.Free;
+  N.Free;
+end;
+
+function TRSA.Verify(const Buffer; Length: Integer; const Sig; SigLen: Integer): Boolean;
+var
+  Hash: THash;
+  Digest: TDigest;
+  N1, N2: TBigNum;
+begin
+  if FHashMethod = hmMD5 then
+    Hash := TMD5.Create
+  else { FHashMethod = hmSHA1 }
+    Hash := TSHA1.Create;
+
+  Digest := Hash.Hash(Buffer, Length);
+  N1 := TBigNum.CreateBytesBE(Digest.Buffer, Digest.Length);
+  N1.Mod_(FN);
+
+  N2 := TBigNum.CreateBytesBE(@Sig, SigLen);
+  Encrypt(N2);
+
+  N2.BitCount := Digest.Length * 8;
+  Result := N1.Compare(N2) = 0;
+
+  N1.Free;
+  N2.Free;
+  Hash.Free;
+end;
+
+procedure TRSA.Encrypt(N: TBigNum);
+begin
+  N.PowMod(FE, FN);
+end;
+
+procedure TRSA.Decrypt(N: TBigNum);
+begin
+  N.PowMod(FD, FN);
+end;
+
+procedure TRSA.SavePrivateKey(FileName: string);
+var
+  F: TextFile;
+begin
+  AssignFile(F, FileName);
+  {$I-} Rewrite(F); {$I+}
+  if IOResult <> 0 then
+    Exit;
+  Writeln(F, D.ToHex);
+  Writeln(F, E.ToHex);
+  Writeln(F, N.ToHex);
+  CloseFile(F);
+end;
+
+procedure TRSA.LoadPrivateKey(FileName: string);
+var
+  F: TextFile;
+  S: string;
+begin
+  D.Clear;
+  E.Clear;
+  N.Clear;
+
+  AssignFile(F, FileName);
+  FileMode := 0;
+  {$I-} Reset(F); {$I+}
+  if IOResult <> 0 then
+    Exit;
+
+  Readln(F, S);
+  D.CopyHex(S);
+  Readln(F, S);
+  E.CopyHex(S);
+  Readln(F, S);
+  N.CopyHex(S);
+
+  CloseFile(F);
+end;
+
+procedure TRSA.SavePublicKey(FileName: string);
+var
+  F: TextFile;
+begin
+  AssignFile(F, FileName);
+  {$I-} Rewrite(F); {$I+}
+  if IOResult <> 0 then
+    Exit;
+  Writeln(F, E.ToHex);
+  Writeln(F, N.ToHex);
+  CloseFile(F);
+end;
+
+procedure TRSA.LoadPublicKey(FileName: string);
+var
+  F: TextFile;
+  S: string;
+begin
+  E.Clear;
+  N.Clear;
+
+  AssignFile(F, FileName);
+  FileMode := 0;
+  {$I-} Reset(F); {$I+}
+  if IOResult <> 0 then
+    Exit;
+
+  Readln(F, S);
+  E.CopyHex(S);
+  Readln(F, S);
+  N.CopyHex(S);
+
+  CloseFile(F);
+end;
+
+end.
+