PKCS7 Decrypt MIME

Loads a PKCS7 encrypted MIME file and decrypts.

Download Chilkat MIME ActiveX

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
mime: CHILKATMIMELib_TLB.IChilkatMime;
success: Integer;
pfxPassword: String;

begin
mime := CoChilkatMime.Create();

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

//  Load the MIME
success := mime.LoadMimeFile('encrypted.mim');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Decrypt...
success := mime.Decrypt();
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

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

//  How is it possible to magically decrypt with no information?
//  Answer: It is possible to decrypt if the certificate with private key
//  needed for decryption was previously installed onto the
//  Windows computer.  PKCS7 encrypted (enveloped) data always
//  includes information about the certificate required for
//  decryption.  Chilkat uses it to automatically search the
//  Windows registry-based certificate stores to find the
//  certificate.

//  If the certificate required for decryption was not installed, but
//  you have a PFX file containing the cert + private key,
//  then it may be used like this:

//  The AddPfxSourceFile and/or AddPfxSourceData
//  methods may be called one or more times (one per PFX)
//  to add sources from which the MIME component will
// search for certificates and private keys when decrypting.
pfxPassword := 'myPassword';
success := mime.AddPfxSourceFile('myCertAndPrivateKey.pfx',pfxPassword);
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Now call Decrypt, and it will search the PFX sources
//  previously added...

end;