Delphi DLL

Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, BinData, PrivateKey, Rsa, PublicKey;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
pubKey: HCkPublicKey;
rsa: HCkRsa;
bd: HCkBinData;
i: Integer;
privKey: HCkPrivateKey;
password: PWideChar;

begin
success := False;

// 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 := CkPublicKey_Create();
// In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success := CkPublicKey_LoadFromFile(pubKey,'rsaKeys/myTestRsaPublic.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

rsa := CkRsa_Create();

// Tell RSA to use the public key.
CkRsa_UsePublicKey(rsa,pubKey);

// 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

// Create some binary data to encrypt.
bd := CkBinData_Create();
i := 0;
for i := 0 to 49 do
  begin
    CkBinData_AppendByte(bd,i);
  end;

// Show the bytes to be encrypted in hex format:
Memo1.Lines.Add('To be encrypted: ' + CkBinData__getEncoded(bd,'hex'));

// To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

// RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
CkRsa_EncryptBd(rsa,bd,False);

// Now it is encrypted.
Memo1.Lines.Add('Encrypted size = ' + IntToStr(CkBinData_getNumBytes(bd)));
Memo1.Lines.Add(CkBinData__getEncoded(bd,'hex'));

// Encrypted size = 256
// 749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
// EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
// 60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
// BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
// 447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
// C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
// 5018C36D3D48B2EF5202AF61AC

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

// Load the matching 2048-bit RSA private key.
privKey := CkPrivateKey_Create();
password := 'secret';
success := CkPrivateKey_LoadAnyFormatFile(privKey,'rsaKeys/myTestRsaPrivate.pem',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

// Tell the RSA object to use the private key.
CkRsa_UsePrivateKey(rsa,privKey);

// Decrypt
success := CkRsa_DecryptBd(rsa,bd,True);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// Examine the contents of bd to see if it now contains the unencrypted original data.
Memo1.Lines.Add('Decrypted: ' + CkBinData__getEncoded(bd,'hex'));

// Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

CkPublicKey_Dispose(pubKey);
CkRsa_Dispose(rsa);
CkBinData_Dispose(bd);
CkPrivateKey_Dispose(privKey);

end;