(PHP 8)
openssl_cms_decrypt — Decrypt a CMS message
$input_filename,$output_filename,$certificate,$private_key = null ,$encoding = OPENSSL_ENCODING_SMIME Decrypts a CMS message.
input_filenameThe name of a file containing encrypted content.
output_filenameThe name of the file to deposit the decrypted content.
certificateThe name of the file containing a certificate of the recipient.
private_keyThe name of the file containing a PKCS#8 key.
encoding
The encoding of the input file. One of OPENSSL_ENCODING_SMIME ,
OPENSSL_ENCODING_DER or OPENSSL_ENCODING_PEM .
It took me a while to find out the correct way how to decrypt and verify data with these functions.
I needed that to communicate with German Health Insurance Providers as part of a DiGA. Maybe someone finds that useful.
<?php
function decryptAndVerify($signedAndEncryptedRawData): string
{
$tempDir = __DIR__ . '/tmp';
$originalFile = tempnam($tempDir, 'original');
$decryptedFile = tempnam($tempDir, 'decrypted');
$verifiedFile = tempnam($tempDir, 'verified');
file_put_contents($originalFile, $signedAndEncryptedRawData);
// One file with all possible certificates one after the other
// -----BEGIN CERTIFICATE----- ...-----END CERTIFICATE-----
$allPossibleSenderCertificates = __DIR__ . '/untrusted.pem';
// Certificate:
// Data:
// Version: 3 (0x2)...
$myCertificate = file_get_contents(__DIR__ . '/my.crt');
$myPrivateKey = openssl_pkey_get_private(
// -----BEGIN RSA PRIVATE KEY----- ... -----END RSA PRIVATE KEY-----
file_get_contents(__DIR__ . '/my.prv.key.pem')
);
openssl_cms_decrypt(
input_filename: $originalFile,
output_filename: $decryptedFile,
certificate: $myCertificate,
private_key: $myPrivateKey,
encoding: OPENSSL_ENCODING_DER
);
openssl_cms_verify(
input_filename: $decryptedFile,
flags: OPENSSL_CMS_BINARY | OPENSSL_CMS_NOSIGS | OPENSSL_CMS_NOVERIFY,
ca_info: [],
untrusted_certificates_filename: $allPossibleSenderCertificates,
content: $verifiedFile,
encoding: OPENSSL_ENCODING_DER
);
return file_get_contents($verifiedFile);
}