PHP

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. Chilkat2 PHP

<?php

use Chilkat2\BinData;
use Chilkat2\Cert;
use Chilkat2\Crypt2;

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

$crypt = new Crypt2();

// 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 = new Cert();
$cert1->LoadFromFile('qa_data/user1/cert_user1.pem');
// Assume success for the example, but make sure your application checks for success/failure...
$crypt->SetEncryptCert($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.
$crypt->CryptAlgorithm = 'pki';
$crypt->Pkcs7CryptAlg = 'aes';
$crypt->KeyLength = 256;
$crypt->OaepHash = 'sha256';
$crypt->OaepPadding = true;

// Load the file to be encrypted...
$fileData = new BinData();
$fileData->LoadFile('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.
try {
    $crypt->EncryptBd($fileData);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

// Save the PKCS7 encrypted message to a file..
$fileData->WriteFile('qa_output/pkcs7_encrypted.p7');

echo "OK.\n";