(PHP Extension) Encrypt File to PKCS7 .p7m

PHP Extension 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.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

$crypt = new CkCrypt2();

// 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->put_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->put_Pkcs7CryptAlg('aes');
$crypt->put_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 = new CkCert();
$success = $encryptCert->LoadFromFile('/Users/chilkat/testData/cer/acme.cer');
if ($success != true) {
    print $encryptCert->lastErrorText() . "\n";
    exit;
}

// Tell the crypt object to use the certificate for encrypting:
$crypt->AddEncryptCert($encryptCert);

// 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 != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// For demonstration purposes, a different instance of the object will be used
// for decryption.
$decrypt = new CkCrypt2();

// 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 != true) {
    print $decrypt->lastErrorText() . "\n";
    exit;
}

// Tell the decrypt object that PKI (public key encryption) is to be used
// for decryptiong.
$decrypt->put_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 == false) {
    print $decrypt->lastErrorText() . "\n";
    exit;
}

print 'Success!' . "\n";

?>