Set up Key StorageThis guide shows how to use key storage in order to save or load user's Private Key.Prerequisites for workInstall SDK and Set up Virgil CryptoThe Virgil SDK is provided as a package named virgil/sdk. The package is distributed via composer package management system.You need to install php virgil crypto extension ext-virgil_crypto_php as one of dependency otherwise you will get the requested PHP extension virgil_crypto_php is missing from your system error during composer install.In general to install virgil crypto extension follow next steps:Download proper extension package for your platform from cdn like virgil-crypto-2.0.4-php-5.6-linux-x86_64.tgz.Type following command to unpack extension in terminal:$ tar -xvzf virgil-crypto-2.0.4-php-5.6-linux-x86_64.tgzPlace unpacked virgil_crypto_php.so under php extension path.Add virgil extension to your php.ini configuration file like extension = virgil_crypto_php.so.$ echo "extension=virgil_crypto_php.so" >> \ `php --ini | grep "Loaded Configuration" | sed -e "s|.*:\s*||"`All necessary information about where php.ini or extension_dir are you can get from php_info() in case run php on server or call php -i | grep php.ini or php -i | grep extension_dir from CLI.Prerequisites:PHP 5.6.*Composervirgil_crypto_php.soInstalling the package:$ composer require virgil/sdkSave a user's Private KeyUse the following lines of code to save a private key after its generation into default protected storage:// save Virgil Key into storage $aliceKey->save('[KEY_NAME]', '[KEY_PASSWORD]');Load a user's Private KeyUser needs own private key to sign some data, decrypt encrypted content, or perform other cryptographic operations.Use the following lines of code to load a private key from key storage:// load Alice's Key from storage. $aliceKey = $virgilApi->Keys->load('[KEY_NAME]', '[KEY_PASSWORD]');In order to use a specific key storage, developers need to change key storage parameters during Virgil SDK initialization.