PHP

Save a Private Key as a Traditional DER File

Demonstrates the Chilkat PrivateKey.SavePkcs1File method, which saves the key using the traditional/preferred unencrypted DER representation. 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: This writes the older, algorithm-specific DER structure — useful for compatibility with tools that predate or do not accept PKCS #8. For new work, PKCS #8 (SavePkcs8File) is more interoperable. The output is unencrypted, so protect the file accordingly.

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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 using the traditional/preferred unencrypted DER representation.
    $privKey->SavePkcs1File('qa_output/private_pkcs1.der');
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo "Saved.\n";