With headlines about security breaches seemingly popping up every few days, we've become much more aware about online privacy and the dangers of digital snooping and identity and data theft.
Even as government agencies and tech companies weigh the balance between privacy and public security, app makers have been busy creating encrypted messaging tools, or adding end-to-end encryption to existing messaging services to meet the demands of users who have become more concerned about online privacy.
Check out some of the best mobile encrypted messaging apps available right now for Android and iOS devices.
Signal (Android, iOS: Free)
Open Whisper Systems' Signal is a fantastic messaging solution for security-conscious mobile users. It's a free all-in-one messaging and voice-call solution that uses end-to-end encryption.
You can send text messages, voice calls, group messages, media and attachments to your phone contacts, all without having to mess with PIN codes or special login credentials. Messages can also be set to self-destruct after a certain amount of time. A newly added Chrome browser plugin lets you use Signal from your desktop as well.
Ease of use and strong, open-source, regularly audited encryption makes Signal a favorite of the security-conscious, with accolades from Edward Snowden and other privacy advocates. User-friendliness without compromising on security makes Signal a fantastic option for users looking for an encrypted messaging and calling app.
Silence (Android: Free)
If you're looking for an SMS/MMS app that offers a bit more security than your standard messenger app, check out Silence, an open-source Android app that takes the Axolotl encryption protocol pioneered by Open Whisper Systems and the Signal app and applies it to SMS.
Silence works just like your normal SMS messaging app, sending normal text messages to your contacts through SMS, with the option of sending encrypted SMS messages to other Silence users.
Silence is not currently available in the Google Play Store, apparently due to unexplained trademark issues. We don't normally recommend sideloading apps, but the Silence app is available in the F-Droid open-source app repository.
Download Silence: Android
Silent Phone (Android, iOS: $9.95 per month)
Silent Circle is a trusted provider of secure-communications software and hardware, such as the Blackphone, and it has also developed its own secure mobile-messaging platform.
Silent Phone provides encrypted video and voice calls, as well as encrypted, self-destructing messaging and file transfers. Encryption keys are held by subscribers themselves, not by Silent Circle, so while your encrypted messages may pass through Silent Circle's network, the company can't read your data.
Telegram (Android, iOS: Free)
Telegram used to be the poster child for secure messaging, allowing users to link their phone number to a Telegram account to send fast, encrypted messaging over the net, with client-server encryption for standard chats.
That said, unlike other encrypted messaging apps, end-to-end encryption is not enabled by default, requiring you to switch to a Secure Chat mode. You can set messages to self-destruct, share videos and documents, and participate in group chats of up to 200,000 users. (Yes, they really do support group chats that large.)
A caveat? Telegram uses its own custom MTProto encryption rather than a more proven system, and some information-security experts warn that aside from its group chats, Telegram isn't very secure.
Cyphr (Android, iOS: Free)
Golden Frog, the maker of the popular Vypr VPN service, has also entered the encrypted messaging field with Cyphr. The app provides end-to-end encryption, with only a minimal amount of metadata stored in Cyphr's servers, which are only stored temporarily until your message is received. Messages are encrypted with a combination of technologies including AES 256, public and private key pairings, public key verification, and SSL for message delivery. More features are in development, such as desktop apps and multi-device support.
Wire (Android, iOS: Free)
European firm Wire Swiss also has a feature-rich encrpyted messenger app on offer, compliant with European data protection laws.
Wire features end-to-end encryption for text messages, voice and video calls, with support for GIFs, audio and video clips, and sketches, and local and Dropbox file sharing. The app also offers multiplatform cross-device syncing and support for multiple accounts, allowing you to separate personal and work communications.
Wire uses its own Proteus encryption protocol inspired by Signal, and its code is open source and subject to external security audits. The mobile and web versions of the app are free, with a premium tier available for businesses.
Dust (Android, iOS: Free)
Dust, formerly Cyber Dust, is another private messaging app that throws in multiple and security and encryption features in an attempt to maintain user privacy.
The app uses a combination of AES-128 and RSA-2048 encryption to secure posts and messages, and it’s also designed to keep direct messages in RAM as much as possible, rather than in your phone's permanent storage. Messages can be set to self-destruct within 24-hours or right after being read.
Dust is also set not to display user names in a message, and informs you if a screenshot is taken from within the app. In addition to the secure messenger, Dust also packs in a privacy watchdog feature and a stealth search tool for maintaining privacy while searching the web.
Pryvate (Android, iOS)
Pryvate is another encrypted messaging app, built with professional and business users in mind. But the app still offers some solid functionality even in its free tier.
The Pryvate Now messenger offers RSA-4096 encrypted voice and IM messaging functions, as well as self-destructing messages. Users willing to spring for premium subscriptions get private voice and video calls, secured conference calls, private email, file storage and anti-blocking measures so that you can use the app globally.
RokaCom (Android, iOS: pricing varies on per-user basis)
Another private communications app that's designed to meet the needs of enterprise and government is RokaCom, which offers government-grade secure communications that meet NSA Suite B and CNSB standards.
The app offers a balance of ease of use and functionality, with multi-device syncing, secure voice, messaging, and file transfers, all protected by end-to-end encryption. RokaCom requires both sender and recipient to have the app for properly secure communications, and organizations have the option of using RokaCom's cloud infrastructure or private (or even on-site) servers. It's a pricey but impressive offering.
Wickr Me (Android, iOS: Free)
Wickr Me is a free end-to-end encrypted-messaging app that allows users to send private, self-destructing messages (text, photo, video, and voice) to other Wickr contacts.
The app takes user privacy seriously, using strong encryption and deleting metadata such as geotags and message times, and users can configure how long it takes for messages to self-destruct. A new video key verification system adds a new layer of security, with users verifying each other with short bursts of encrypted video.
The app's security is a point of pride for Wickr; there's even a $100,000 bug-bounty program for anyone who gets in touch with the company to point out a security flaw.
WhatsApp (Android, iOS: Free)
With the aid of Open Whisper Systems, WhatsApp added end-to-end encryption to all messages in 2016, and the messaging giant hasn't been complacent, continuously adding tweaks to the app's security and privacy features, such as fine-tuned group invites and controls so that you're always aware who is reading your group chats.
Users who want to be absolutely sure about their security can verify each chat's 60-digit security-verification code or QR code that you can compare with a contact to ensure that your conversation is encrypted.
Combined with WhatsApp's ubiquity, ease of use and the ability to send voice messages, photos, and video messages, and conduct group chats, this makes for a robust and, now, fully encrypted mobile-messaging app.
Facebook Messenger (Android, iOS: Free)
The near-ubiquitous Facebook Messenger may not be the first app you think of when it comes to encrypted messaging, but the mobile versions of the app do include end-to-end encrypted communication options in the form of Secret Conversations.
Based on the same encryption system used in Signal, Secret Conversations requires users to opt-in to the feature, and allows them to send and receive encrypted text, pictures, and stickers to and from a single mobile device, with the option for time-limited self-destructing messages a la Snapchat.
That said, Facebook Messenger — which is in the midst of rolling out a new, streamlined interface — is still vulnerable to being screen-grabbed, and the opt-in and single-device limitations can be an issue.
Viber (Android, iOS: Free)
Not to be outdone, Viber has also thrown its hat into the secure-messaging ring, announcing the addition of end-to-end encryption on all platforms in its latest update.
A neat feature for Viber is the addition of a color-coded lock icon to quickly show users how protected a conversation is (gray for encrypted comms, green for encrypted comms with a trusted contact, and red in the event that there is an issue with the authentication key). In addition, Viber has also added a Hidden Chats feature for hiding chatrooms on a shared device.
All of this is in addition to Viber's solid mobile-messaging feature set, including text, voice, and group messaging all tied to your phone number. The app and communications with other Viber users are free; you'll have to pay a bit for calls to non-Viber users.
Voxer (Android, iOS)
Voxer takes a more voice-oriented approach than a lot of these other apps, allowing users to send voice messages similar to a walkie-talkie or push-to-talk device.
Users can listen to messages live in-app or play back messages like voice mail later on; they can also send and receive text, photos, videos, and location messages. In addition to direct messaging, the app supports groups of up to 500 individuals, and optional encrypted messaging using the Signal protocol.
The app is free, but a premium subscription unlocks features such as unlimited message history, admin controls for group chats, and a hands-free walkie-talkie mode. You will need to opt in to encrypted messaging with the Private Chat mode, rather than have it on as default though.
Threema (Android, iOS: $2.99)
Threema is a mobile end-to-end encrypted messaging app that uses the NaCl cryptography library to protect your communications.
When you fire up the app, it generates a unique Threema ID key, allowing you to use the app completely anonymously, with the option of associating it with an email address or phone number, and scannable QR codes available for user verification.
In addition to the usual raft of messaging features such as encrypted text, voice, picture, and video messaging, the app also includes file sharing (20MB per file), group messaging and a polling system for getting feedback from friends and contacts.