Delphi DLL

RSA Encrypt and Decrypt Strings

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt strings using public and private keys. Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
rsa: HCkRsa;
privKey: HCkPrivateKey;
pubKey: HCkPublicKey;
plainText: PWideChar;
rsaEncryptor: HCkRsa;
usePrivateKey: Boolean;
encryptedStr: PWideChar;
rsaDecryptor: HCkRsa;
decryptedStr: PWideChar;

begin
success := False;

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

rsa := CkRsa_Create();

// This example also generates the public and private
// keys to be used in the RSA encryption.
// Normally, you would generate a key pair once,
// and distribute the public key to your partner.
// Anything encrypted with the public key can be
// decrypted with the private key.  The reverse is 
// also true: anything encrypted using the private
// key can be decrypted using the public key.

// Generate a 2048-bit key.  Chilkat RSA supports
// key sizes ranging from 512 bits to 4096 bits.
privKey := CkPrivateKey_Create();
success := CkRsa_GenKey(rsa,2048,privKey);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

pubKey := CkPublicKey_Create();
CkPrivateKey_ToPublicKey(privKey,pubKey);

plainText := 'Encrypting and decrypting should be easy!';

// Start with a new RSA object to demonstrate that all we
// need are the keys previously exported:
rsaEncryptor := CkRsa_Create();

// Encrypted output is always binary.  In this case, we want
// to encode the encrypted bytes in a printable string.
// Our choices are "hex", "base64", "url", "quoted-printable".
CkRsa_putEncodingMode(rsaEncryptor,'hex');

// We'll encrypt with the public key and decrypt with the private
// key.
success := CkRsa_UsePublicKey(rsaEncryptor,pubKey);

usePrivateKey := False;
encryptedStr := CkRsa__encryptStringENC(rsaEncryptor,plainText,usePrivateKey);
Memo1.Lines.Add(encryptedStr);

// Now decrypt:
rsaDecryptor := CkRsa_Create();

CkRsa_putEncodingMode(rsaDecryptor,'hex');
success := CkRsa_UsePrivateKey(rsaDecryptor,privKey);

usePrivateKey := True;
decryptedStr := CkRsa__decryptStringENC(rsaDecryptor,encryptedStr,usePrivateKey);

Memo1.Lines.Add(decryptedStr);

CkRsa_Dispose(rsa);
CkPrivateKey_Dispose(privKey);
CkPublicKey_Dispose(pubKey);
CkRsa_Dispose(rsaEncryptor);
CkRsa_Dispose(rsaDecryptor);

end;