Yahoo reportedly created the program to comply with a U.S. classified government directive. The mass email searching was so secretive that not even Yahoo’s own security team was unaware of it, Reuters reports. The company was searching for a “set of characters,” possibly a phrase in an email or attachment, it’s unclear if the program is still in use. It’s unclear what Yahoo was looking for and if Yahoo handed over any information to the NSA or FBI. News comes after the company reported a massive data breach affecting 500 million user accounts.”]