PHP

Save a Private Key as a PKCS #8 DER File

Demonstrates the Chilkat PrivateKey.SavePkcs8File method, which saves the key as unencrypted PKCS #8 DER to a file. The only argument is the destination path.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: The file-writing counterpart to GetPkcs8ENC/GetPkcs8Pem, producing a compact binary .der in the algorithm-independent PKCS #8 container. Because it is unencrypted, the file itself is the only protection for the key — store it with restrictive permissions, or use SavePkcs8EncryptedFile to add a passphrase.

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<?php

use Chilkat2\PrivateKey;

// Load a private key to export.
$privKey = new PrivateKey();
try {
    $privKey->LoadPemFile('qa_data/private.pem');

    // Save as unencrypted PKCS #8 DER.
    $privKey->SavePkcs8File('qa_output/private_pkcs8.der');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo "Saved.\n";