(Delphi ActiveX) RSA Encrypt RSA/ECB/OAEPWithSHA1AndMGF1Padding

Demonstrates how to RSA encrypt using RSA/ECB/OAEPWithSHA1AndMGF1Padding. Also demonstrates RSA/ECB/OAEPWithSHA-256AndMGF1Padding. Both of these terms are from Java's JCE. Note: In this context, "ECB" doesn't actually mean anything. It's a symmetric cipher mode that doesn't apply (or make sense) in this context.

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
rsa: TChilkatRsa;
pubkey: TPublicKey;
success: Integer;
plainText: WideString;
usePrivateKey: Integer;
encryptedStr: WideString;
rsa2: TChilkatRsa;
privKey: TPrivateKey;
originalStr: WideString;

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

rsa := TChilkatRsa.Create(Self);

// First load a public key object with a public key.
// In this case, we'll load it from a file.
pubkey := TPublicKey.Create(Self);
success := pubkey.LoadFromFile('qa_data/pem/rsa_public.pem');
if (success <> 1) then
  begin
    Memo1.Lines.Add(pubkey.LastErrorText);
    Exit;
  end;

// RSA encryption is limited to small amounts of data. The limit
// is typically a few hundred bytes and is based on the key size and
// padding (OAEP vs. PKCS1_5).  RSA encryption is typically used for
// encrypting hashes or symmetric (bulk encryption algorithm) secret keys.
plainText := 'Time is an illusion. Lunchtime doubly so.';

// Import the public key to be used for encrypting.
success := rsa.ImportPublicKeyObj(pubkey.ControlInterface);

// To get OAEP padding, set the OaepPadding property:
rsa.OaepPadding := 1;

// To use SHA1 or SHA-256, set the OaepHash property
rsa.OaepHash := 'sha256';
// for SHA1 --
rsa.OaepHash := 'sha1';

// Indicate we'll want hex output
rsa.EncodingMode := 'hex';

// Encrypt..
usePrivateKey := 0;
encryptedStr := rsa.EncryptStringENC(plainText,usePrivateKey);
Memo1.Lines.Add(encryptedStr);

// -------------------------------------------------
// Now decrypt with the matching private key.
rsa2 := TChilkatRsa.Create(Self);

privKey := TPrivateKey.Create(Self);
success := privKey.LoadEncryptedPem('qa_data/pem/rsa_passwd.pem','passwd');
if (success <> 1) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

success := rsa2.ImportPrivateKeyObj(privKey.ControlInterface);

// Make sure we have the same settings used for encryption.
rsa2.OaepPadding := 1;
rsa2.EncodingMode := 'hex';
rsa2.OaepHash := 'sha1';

originalStr := rsa2.DecryptStringENC(encryptedStr,1);

Memo1.Lines.Add(originalStr);
end;