Some of the most widely used messaging apps in the world, including Google Hangouts, Facebook chat, Yahoo Messenger, and Snapchat, flunked a best-practices security test by advocacy group the Electronic Frontier Foundation (EFF).
The organization evaluated 39 messaging products based on seven criteria it believes such tools should meet in order to ensure the privacy and security of digital communications.
The reviewed products included mobile texting apps, instant messaging clients, voice and video calling software and email services. The results were published Tuesday under the form of a Secure Messaging Scorecard.
The EFF did not perform vulnerability assessments or in-depth technical analyses of the encryption implementations in the reviewed products. Instead it judged them based on principles and features it felt are necessary to protect communications from widespread Internet surveillance by governments, which includes data collection in transit or from online service providers.
When reviewing the products, the EFF asked the following questions:
- Does the application encrypt data in transit?
- Is the communication encrypted with a key the provider doesn’t have access to? This requires the use of encryption keys negotiated directly between user clients, also known as end-to-end encryption.
- Can users independently verify the identity of contacts they are speaking to even if the service provider is compromised?
- Do previous communications remain secure even if users’ long-term private keys are compromised? This property, known as forward secrecy requires cryptographic implementations that use ephemeral encryption keys for every session.
- Is the product’s code for communication and encryption open to independent review?
- Is the product’s cryptographic design well documented? This requires listing the product’s encryption and authentication algorithms; documenting the key generation, storage and exchange mechanisms; describing the process of revoking and changing keys; stating the protections the software aims to provide and the scenarios where it might not be secure.
- Has the product’s design and implementation been subjected to an independent security audit in the previous twelve months? An audit by a security team that is independent of the product’s development team within the same organization is sufficient.
Six applications, most of them open source, met all of the EFF’s requirements: CryptoCat, a Web-based instant messaging application; ChatSecure, an encrypted chat client for iPhone and Android; TextSecure, a text messaging app for Android; RedPhone, an encrypted calling app for Android and Signal, its version for iOS; Silent Text and Silent Phone, the encrypted texting and calling apps by secure communications provider Silent Circle.
There were other apps that came close, failing on just one criteria—the annual code audit or the forward secrecy requirements. These products were Mailvelope, RetroShare, Subrosa, Jitsi, Adium, and Pidgin.
Of the mass-market products, Apple’s iMessage and FaceTime scored the highest, failing on only two requirements—the availability of code for independent review and the out-of-band contact identity verification. This means they don’t currently provide complete protection against sophisticated, targeted forms of surveillance, the EFF said.
Other widely used communication tools scored much worse, meeting only one or two of the seven requirements. This was the case of Google Hangouts, Facebook chat, Yahoo Messenger, Snapchat, WhatsApp, Viber, AIM, BlackBerry Messenger and several others. None of these products offer end-to-end encryption making communications through them susceptible to surveillance on the provider’s side.
South African mobile social network Mxit and widely used Chinese instant messaging service QQ don’t provide encryption at all, making them the least secure products of the 39 that were tested.