Encrypted messaging app Signal is helping users become even more secretive with support for disappearing messages.

Users can now put a timer on how long a chat message will be available to recipients, from five seconds to one week. Once the timer is up, Signal removes the message, never to be seen again.

"Disappearing messages are a way for you and your friends to keep your message history tidy," Whisper Systems said in a blog post. "They are a collaborative feature for conversations where all participants want to automate minimalist data hygiene, not for situations where your contact is your adversary — after all, if someone who receives a disappearing message really wants a record of it, they can always use another camera to take a photo of the screen before the message disappears."

Signal is one of several messaging apps that support end-to-end encryption, ensuring outsiders can't snoop on conversations between two people. It's one of many—like Google's WhatsApp, Apple's iMessage, and Telegram—that have come under fire from law enforcement officials who want to keep tabs on the conversations of suspected criminals, but cannot when end-to-end encryption is in place. The tech industry has little sympathy, particularly in a post-Snowden world.

Signal also now comes with support for Signal Protocol's number fingerprint format. Dubbed "safety numbers," the format is meant to replace hex strings to verify the app's security. The safety numbers can be verified by scanning a QR code or reading aloud the numbers to the app.

The new and improved Signal is available now on the desktop, iOS, and Android.