PKCS7 Encrypt using Multiple Certificates

Encrypts MIME using multiple digital certificates. Calls AddEncryptCert once per certificate, followed by a call to EncryptN. The MIME may be decrypted by any owner of one of the certificates + its associated private key.

Download Chilkat MIME ActiveX

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    CHILKATMIMELib_TLB,
    CHILKATCERTIFICATELib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
mime: CHILKATMIMELib_TLB.IChilkatMime;
success: Integer;
cert1: TChilkatCert;
cert2: TChilkatCert;

begin

mime := CoChilkatMime.Create();

success := mime.UnlockComponent('Anything for 30-day trial.');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Build a simple MIME message to be encrypted:
mime.AddHeaderField('Content-Type','text/plain');
mime.AddHeaderField('abc','123');
mime.SetBody('This is a test');

//  A digital certificate is required to create PKCS7 encrypted MIME.
//  It can come from a variety of sources: .cer file, .pfx file, PEM files,
//  an in-memory representation, or directly from a Windows
//  registry-based certificate store.

//  Load one cert from a .cer file:
cert1 := TChilkatCert.Create(Self);
success := cert1.LoadFromFile('myCert.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert1.LastErrorText);
    Exit;
  end;

//  Load another cert from the Windows registry store:
cert2 := TChilkatCert.Create(Self);
success := cert2.LoadByCommonName('Chilkat Sales');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert2.LastErrorText);
    Exit;
  end;

//  Tell the MIME object to use these certs for encrypting:
//  (AddEncryptCert shouldn't fail if we already know it contains
//  a valid certificate..)
success := mime.AddEncryptCert(cert1.ControlInterface As CHILKATMIMELib_TLB.IChilkatCert);
success := mime.AddEncryptCert(cert2.ControlInterface As CHILKATMIMELib_TLB.IChilkatCert);

//  Encrypt the MIME:
success := mime.EncryptN();
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Display the MIME:
Memo1.Lines.Add(mime.GetMime());

//  The resulting S/MIME looks something like this:
//  
abc: 123
Content-Disposition: attachment; filename="smime.p7m"
Content-Transfer-Encoding: base64
Content-Type: application/x-pkcs7-mime;
 name="smime.p7m"

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end;