(Delphi DLL) 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 non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX 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
rsa: HCkRsa;
pubkey: HCkPublicKey;
success: Boolean;
plainText: PWideChar;
usePrivateKey: Boolean;
encryptedStr: PWideChar;
rsa2: HCkRsa;
privKey: HCkPrivateKey;
originalStr: PWideChar;

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

rsa := CkRsa_Create();

// First load a public key object with a public key.
// In this case, we'll load it from a file.
pubkey := CkPublicKey_Create();
success := CkPublicKey_LoadFromFile(pubkey,'qa_data/pem/rsa_public.pem');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubkey));
    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 := CkRsa_ImportPublicKeyObj(rsa,pubkey);

// To get OAEP padding, set the OaepPadding property:
CkRsa_putOaepPadding(rsa,True);

// To use SHA1 or SHA-256, set the OaepHash property
CkRsa_putOaepHash(rsa,'sha256');
// for SHA1 --
CkRsa_putOaepHash(rsa,'sha1');

// Indicate we'll want hex output
CkRsa_putEncodingMode(rsa,'hex');

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

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

privKey := CkPrivateKey_Create();
success := CkPrivateKey_LoadEncryptedPem(privKey,'qa_data/pem/rsa_passwd.pem','passwd');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

success := CkRsa_ImportPrivateKeyObj(rsa2,privKey);

// Make sure we have the same settings used for encryption.
CkRsa_putOaepPadding(rsa2,True);
CkRsa_putEncodingMode(rsa2,'hex');
CkRsa_putOaepHash(rsa2,'sha1');

originalStr := CkRsa__decryptStringENC(rsa2,encryptedStr,True);

Memo1.Lines.Add(originalStr);

CkRsa_Dispose(rsa);
CkPublicKey_Dispose(pubkey);
CkRsa_Dispose(rsa2);
CkPrivateKey_Dispose(privKey);

end;