Delphi ActiveX

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.) Delphi ActiveX

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
rsa: TChilkatRsa;
privKey: TPrivateKey;
pubKey: TPublicKey;
ccNumber: WideString;
usePrivateKey: Integer;
encryptedStr: WideString;
rsaDecryptor: TChilkatRsa;
decryptedStr: WideString;

begin
success := 0;

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

rsa := TChilkatRsa.Create(Self);

privKey := TPrivateKey.Create(Self);

// Load an RSA private key from a file:
success := privKey.LoadAnyFormatFile('rsaPrivateKey.key','');
if (success = 0) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

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

success := rsa.UsePublicKey(pubKey.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

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

usePrivateKey := 0;
rsa.EncodingMode := 'base64';
encryptedStr := rsa.EncryptStringENC(ccNumber,usePrivateKey);
Memo1.Lines.Add('Encrypted:');
Memo1.Lines.Add(encryptedStr);

// Now decrypt:
rsaDecryptor := TChilkatRsa.Create(Self);

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

usePrivateKey := 1;
decryptedStr := rsaDecryptor.DecryptStringENC(encryptedStr,usePrivateKey);

Memo1.Lines.Add('Decrypted:');
Memo1.Lines.Add(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
end;