(Delphi DLL) 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 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, BinData, Cert, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
crypt: HCkCrypt2;
cert1: HCkCert;
success: Boolean;
fileData: HCkBinData;

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

crypt := CkCrypt2_Create();

// 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 := CkCert_Create();
success := CkCert_LoadFromFile(cert1,'qa_data/user1/cert_user1.pem');
// Assume success for the example, but make sure your application checks for success/failure...
CkCrypt2_SetEncryptCert(crypt,cert1);

// 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.
CkCrypt2_putCryptAlgorithm(crypt,'pki');
CkCrypt2_putPkcs7CryptAlg(crypt,'aes');
CkCrypt2_putKeyLength(crypt,256);
CkCrypt2_putOaepHash(crypt,'sha256');
CkCrypt2_putOaepPadding(crypt,True);

// Load the file to be encrypted...
fileData := CkBinData_Create();
success := CkBinData_LoadFile(fileData,'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 := CkCrypt2_EncryptBd(crypt,fileData);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkCrypt2__lastErrorText(crypt));
    Exit;
  end;

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

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

CkCrypt2_Dispose(crypt);
CkCert_Dispose(cert1);
CkBinData_Dispose(fileData);

end;