protected function validate_transaction( $transaction ) {
		$pdt = array(
			'body'        => array(
				'cmd' => '_notify-synch',
				'tx'  => $transaction,
				'at'  => $this->identity_token,
			),
			'timeout'     => 60,
			'httpversion' => '1.1',
			'user-agent'  => 'WooCommerce/' . Constants::get_constant( 'WC_VERSION' ),
		);

		// Post back to get a response.
		$response = wp_safe_remote_post( $this->sandbox ? 'https://www.sandbox.paypal.com/cgi-bin/webscr' : 'https://www.paypal.com/cgi-bin/webscr', $pdt );

		if ( is_wp_error( $response ) || strpos( $response['body'], 'SUCCESS' ) !== 0 ) {
			return false;
		}

		// Parse transaction result data.
		$transaction_result  = array_map( 'wc_clean', array_map( 'urldecode', explode( "\n", $response['body'] ) ) );
		$transaction_results = array();

		foreach ( $transaction_result as $line ) {
			$line                            = explode( '=', $line );
			$transaction_results[ $line[0] ] = isset( $line[1] ) ? $line[1] : '';
		}

		if ( ! empty( $transaction_results['charset'] ) && function_exists( 'iconv' ) ) {
			foreach ( $transaction_results as $key => $value ) {
				$transaction_results[ $key ] = iconv( $transaction_results['charset'], 'utf-8', $value );
			}
		}

		return $transaction_results;
	}