(Delphi ActiveX) RSA Encrypt String to Binary Result and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt a string to a binary result, and the reverse.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

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
pubKey: TPublicKey;
success: Integer;
rsa: TChilkatRsa;
encBytes: Array of Byte;
privKey: TPrivateKey;
password: WideString;
originalText: WideString;

begin
// The RSA public key is used for encryption, and the private key for decryption.

// The public key's role is to make encryption accessible to anyone while ensuring that
// only the private key holder can decrypt the messages.
// The public key is designed to be widely distributed so anyone can use it to encrypt messages
// intended for the owner of the private key.

// Load our 2048-bit RSA public key.
pubKey := TPublicKey.Create(Self);
// In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success := pubKey.LoadFromFile('qa_data/rsaKeys/myTestRsaPublic.pem');
if (success = 0) then
  begin
    Memo1.Lines.Add(pubKey.LastErrorText);
    Exit;
  end;

rsa := TChilkatRsa.Create(Self);

// Tell RSA to use the public key.
rsa.ImportPublicKeyObj(pubKey.ControlInterface);

// RSA encryption is for small amounts of data, on the order of 200 bytes or less.
// The maximum number of bytes that can be RSA encrypted depends
// on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
// For specific limits, see: RSA Encryption Maximum Number of Bytes

// Encrypt the utf-8 byte representation of the string.
rsa.Charset := 'utf-8';

// Be Careful when Using non-us-ascii String Literals in Source Code

encBytes := rsa.EncryptString('Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux',0);

// ------------------------------------------------------------------------------------------------------------------------
// Let's decrypt, which requires the matching private key...

// Load the matching 2048-bit RSA private key.
privKey := TPrivateKey.Create(Self);
password := 'secret';
success := privKey.LoadAnyFormatFile('qa_data/rsaKeys/myTestRsaPrivate.pem',password);
if (success = 0) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

// Tell the RSA object to use the private key.
rsa.ImportPrivateKeyObj(privKey.ControlInterface);

// Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
rsa.Charset := 'utf-8';
originalText := rsa.DecryptString(encBytes,1);
if (success = 0) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Original text = ' + originalText);
Memo1.Lines.Add('Success.');
end;