(Delphi ActiveX) Encrypt File to PKCS7 .p7m

Delphi ActiveX example to public-key encrypt a file creating a PKCS#7 .p7m file as output. Also demonstrates how to decrypt the .p7m to recover the original file.

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;
encryptCert: TChilkatCert;
success: Integer;
inFile: WideString;
outFile: WideString;
decrypt: TChilkatCrypt2;
pfxFilename: WideString;
pfxPassword: WideString;

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

crypt := TChilkatCrypt2.Create(Self);

// Indicate the public-key encryption is to be used.
// Do this by setting the encryption algorithm equal 
// to "PKI" (an acroynm for public-key infrastructure).
crypt.CryptAlgorithm := 'PKI';

// Indicate the inner symmetric encryption algorithm to be used.
// possible values are "aes", "des", "3des", and "rc2".
// For this example, we'll use 256-bit AES encryption.
crypt.Pkcs7CryptAlg := 'aes';
crypt.KeyLength := 256;

// To encrypt, only a certificate w/ public key is needed.
// (The certificate w/ private key is required for decryption.)

// The LoadFromFile method can load virtually any certificate format:
// 1. DER encoded binary X.509 (.CER)
// 2. Base-64 encoded X.509 (.CER)
// 3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)
// 4. PEM format
encryptCert := TChilkatCert.Create(Self);
success := encryptCert.LoadFromFile('/Users/chilkat/testData/cer/acme.cer');
if (success <> 1) then
  begin
    Memo1.Lines.Add(encryptCert.LastErrorText);
    Exit;
  end;

// Tell the crypt object to use the certificate for encrypting:
crypt.AddEncryptCert(encryptCert.ControlInterface);

// Encrypt a file, producing a .p7m as output.
// The input file is unchanged, the output .p7m contains the encrypted
// contents of the input file.
inFile := '/Users/chilkat/testData/pdf/sample.pdf';
outFile := '/Users/chilkat/testData/p7m/sample.pdf.p7m';
success := crypt.CkEncryptFile(inFile,outFile);
if (success <> 1) then
  begin
    Memo1.Lines.Add(crypt.LastErrorText);
    Exit;
  end;

// For demonstration purposes, a different instance of the object will be used
// for decryption.
decrypt := TChilkatCrypt2.Create(Self);

// To decrypt, the certificate w/ private key is required.  A PFX (also known
// as PKCS#12) is a common secure container for certs and private keys.
pfxFilename := '/Users/chilkat/testData/pfx/acme.pfx';
pfxPassword := 'secret';

// Tell the component to look in the PFX file for certs and private keys.
success := decrypt.AddPfxSourceFile(pfxFilename,pfxPassword);
if (success <> 1) then
  begin
    Memo1.Lines.Add(decrypt.LastErrorText);
    Exit;
  end;

// Tell the decrypt object that PKI (public key encryption) is to be used
// for decryptiong.
decrypt.CryptAlgorithm := 'PKI';
// There is no need to set the Pkcs7Alg or KeyLength because this information
// is contained within the .p7m

// Decrypt the .p7m
inFile := '/Users/chilkat/testData/p7m/sample.pdf.p7m';
outFile := '/Users/chilkat/testData/pdf/recovered.pdf';
success := decrypt.CkDecryptFile(inFile,outFile);
if (success = 0) then
  begin
    Memo1.Lines.Add(decrypt.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Success!');
end;