(Delphi ActiveX) Encrypt a File to a PKCS7 (CMS) Message

Shows how to encrypt a file into a PKCS7 encrypted message using the recipient's certificate. Public-key encryption requires no private key. However, the recipient's private key is necessary for decryption.

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
crypt: TChilkatCrypt2;
cert1: TChilkatCert;
success: Integer;
fileData: TChilkatBinData;

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

crypt := TChilkatCrypt2.Create(Self);

// Load the recipient's digital certificate. 
// We don't need the private key for encryption.
// Only the public key is needed (which is included in a certificate).
cert1 := TChilkatCert.Create(Self);
success := cert1.LoadFromFile('qa_data/user1/cert_user1.pem');
// Assume success for the example, but make sure your application checks for success/failure...
crypt.SetEncryptCert(cert1.ControlInterface);

// Indicate that we want PKI encryption (i.e. public-key infrastructure)
// to produce a CMS message (Cryptographic Message Syntax/PKCS7),
// that is be created with RSAES-OAEP padding, SHA256, and AES-256 for the
// bulk encryption.
crypt.CryptAlgorithm := 'pki';
crypt.Pkcs7CryptAlg := 'aes';
crypt.KeyLength := 256;
crypt.OaepHash := 'sha256';
crypt.OaepPadding := 1;

// Load the file to be encrypted...
fileData := TChilkatBinData.Create(Self);
success := fileData.LoadFile('qa_data/jpg/penguins.jpg');
// Your app should check for success/failure..

// Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
success := crypt.EncryptBd(fileData.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// Save the PKCS7 encrypted message to a file..
success := fileData.WriteFile('qa_output/pkcs7_encrypted.p7');

Memo1.Lines.Add('OK.');
end;