Pascal (Lazarus/Delphi)

RSA Encrypt and Decrypt Credit Card Numbers

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.) Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.PrivateKey,
  Chilkat.Rsa,
  Chilkat.PublicKey;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  rsa: TRsa;
  privKey: TPrivateKey;
  pubKey: TPublicKey;
  ccNumber: string;
  usePrivateKey: Boolean;
  encryptedStr: string;
  rsaDecryptor: TRsa;
  decryptedStr: string;

begin
  success := False;

  //  This example assumes the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  rsa := TRsa.Create;

  privKey := TPrivateKey.Create;

  //  Load an RSA private key from a file:
  success := privKey.LoadAnyFormatFile('rsaPrivateKey.key','');
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  //  Get the public part of the private key.
  pubKey := TPublicKey.Create;
  privKey.ToPublicKey(pubKey);

  success := rsa.UsePublicKey(pubKey);
  if (success = False) then
    begin
      WriteLn(rsa.LastErrorText);
      Exit;
    end;

  //  Encrypt a VISA credit card number:
  //  1234-5678-0000-9999
  ccNumber := '1234567800009999';

  usePrivateKey := False;
  rsa.EncodingMode := 'base64';
  encryptedStr := rsa.EncryptStringENC(ccNumber,usePrivateKey);
  WriteLn('Encrypted:');
  WriteLn(encryptedStr);

  //  Now decrypt:
  rsaDecryptor := TRsa.Create;

  rsaDecryptor.EncodingMode := 'base64';
  rsaDecryptor.UsePrivateKey(privKey);

  usePrivateKey := True;
  decryptedStr := rsaDecryptor.DecryptStringENC(encryptedStr,usePrivateKey);

  WriteLn('Decrypted:');
  WriteLn(decryptedStr);

  //  Important: RSA encryption should only be used to encrypt small amounts of data.
  //  It is typically used for encrypting symmetric encryption
  //  keys such that a symmetric encryption algorithm, such as 
  //  AES is then used to encrypt/decrypt bulk data.


  rsa.Free;
  privKey.Free;
  pubKey.Free;
  rsaDecryptor.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.