What is a Cryptophone and how it works

by Silvia Mazzetta Date: 11-09-2020 privacy cryptophone hacker security

The so-called cryptophones, are anti-interception smartphones as they use encryption methods to protect all communication systems.
Here are all the details and the truth about these "unassailable" phones.

The recent Encrochat affair, recently investigated for illegal activities, has brought to light the so-called cryptophones. They are smartphones - legal in themselves - equipped with special encryption systems that should be inviolable and, above all, interception-proof (we will see then that security holes can be found here too).

What are cryptophones?

But exactly what are cryptophones and how do they differ from the normal commercial smartphones that we all use?

The levels of encryption offered by these particular devices are substantially different from the smartphones that we all have in our pockets. And in most cases this increased "armouring" is used for illegal purposes, as we will explain later.

Let's clarify meanwhile that current smartphones, both Android and iOS, have been using encryption in memory and data management, as well as in communication applications (instant messaging) for some years now.

Generally Full Disk Encryption (FDE) is not adopted, typically used in computer hard drives where the entire disk is encrypted. In smartphones, FDE is less secure, so File-based Encryption (FBE), which encodes files individually, is preferred.

Apple introduced encryption in 2014 with iOS 8, based on the user's passcode, which is a key that the company does not know.

In Android came shortly after, with Nougat (Android 8), differentiated according to the many Android brands on the market. Only from Android 10 (2019) storage encryption is present by default on all devices, even low-end ones (so it will no longer be an option of choice for the user).

All this has made the work of the investigators more complicated, when they have to try to enter these devices to read the data. Famous is the case of the iPhone of the San Bernardino massacre (California), with Apple refusing to unlock the killer's iPhone 5c, despite the pressing requests of the FBI.

But under certain conditions this encryption can be broken. Just as smartphones can be spied on or intercepted during their use. The cryptophones we are going to talk about now, exist precisely to eliminate these points of vulnerability, especially for those who have things to hide... That's why among the best customers of these devices are criminal organizations.

Encrypted phones were born many years ago. We remember the first Italian model made in 2004 by Casper Technology: it was called Cryptech, it was based on an HTC phone and used the normal GSM networks.

Then many others were born, in a niche market and often located in a "grey" area, where alongside products sold through traditional commercial channels (for example Amazon), there are other manufacturers suspected of selling to organized crime and accused of trying to make profits especially with that type of customers.

For this reason the cryptophone market is very changeable, with companies that are born and disappear quickly, often affected and dismantled by police actions.

The Encrochat case

The last and most striking case is precisely that of Encrochat: as the excellent Carola Frediani illustrated very well in her article: "Encrochat is the name of the company that sold a "secure" communication service based on cryptophones - smartphones modified in software and hardware to be impossible to hack/intercept/violate - whose encrypted messages were routed through the servers of the same company, scattered around the world".

According to the expert Paolo Dal Checco, "the Encrochat communication system seemed to be armoured, for a long time the police and experts all over Europe were looking for a way to access the Encrochat network and phones (when they were seized), but without success. So how did they manage to breach Encrochat? The authorities gave very little information about the results of the blitz, but it is not excluded that the success of the operation was possible thanks to a mole (an infiltrator or a repentant) that allowed the investigators to take control of the infrastructure (the MDM system) or perhaps by sending to the Encrochat network a specially manipulated update"

So, after investigations lasting months or maybe years (it seems that the investigation started in France in 2017), the police of France, Holland and Great Britain, under the coordination of Europol, managed to open a leak in a system used by about 50 thousand users.

Of these, says Carola Frediani, most (90%) were criminal, according to the French authorities. This is probably the most sophisticated operation, from the computer point of view, conducted in Europe against organized crime. More details on the operation can also be found on the Vice site.

How cryptophones work

Before seeing which models of cryptophones are (or were) on the market, let's try to understand how these devices are built and what their peculiarities are.

The vast majority are standard hardware, usually Android phones or even Blackberry. Changes are almost always made only at software level with the inclusion of an operating system with special security requirements.

The installed operating system disables GPS tracking, Google services, Bluetooth, camera, USB port (which remains in operation only for battery charge), obscures push notifications and blocks any other service that may generate a risk of interception or location. The use of external SD cards is also prohibited.

Calls remain active, but only in VoIP mode, so without the use of GSM network and messaging, but with proprietary and encrypted applications.

n Zphone, for example, the operating system is called Secure OS, while in Blackphone 2 of Silent Circle the pre-installed apps are part of the Silent Suite (which includes Silent Phone for voice calls, Silent Text for messaging and file exchange and Silent Contacts which provides protection and security to contacts in the address book).

Both calls and chat are - obviously - encrypted, with multi-level encryption: Diffie-Hellman encryption, elliptical curve encryption (ECC), PGP (Pretty Good Privacy) for email, OTR for chat and ZRTP for calls, where:

  • OTR (Off-the-Record Messaging) is a cryptographic protocol for instant messaging, which can also be implemented on existing IM systems.
  • ZRTP (where "Z" refers to its inventor, Zimmermann, while "RTP" means Real-time Transport Protocol) is a protocol for secure calls that allows you to make encrypted calls over the Internet.

All this works - through the specially installed apps - only if calls (or messages) take place between two cryptophones belonging to the same network. Calls made to "normal" devices are not encrypted and are susceptible to interception.

With these techniques the metadata and the message headers are also encrypted, adding a level of security to what in traditional messaging (WhatsApp etc.) is the major weak point, in fact, the metadata.

Typically, chat and voice applications are peer-to-peer and user communications are not stored on servers. In addition, you can choose whether or not to store data backups (e.g. contact lists, etc.) and also where to store them. If you choose to do this on the service provider's servers, the backups are encrypted.

Your phone may also work without a SIM card, using only a Wi-Fi network. In other cases, dedicated SIM cards are provided, different from traditional carriers. These are SIM cards that connect to the server network provided by your service provider.

With this trick the cryptophones are protected from MITM (Man in the Middle) attacks made with tools such as IMSI Catcher.

An essential feature of these phones is the presence - necessary - of a server infrastructure made available to the service provider against payment of a fee that is often higher than the purchase cost of the device.

In some cases (such as Encrochat) the annual subscription exceeds 2,000 euros per year. These servers are often located in "offshore" countries (such as Costa Rica), but also Canada, Holland and others. They represent the heart of the service and it is to these servers that investigators target the system.

To appear as "normal" smartphones, cryptophones can load two different operating systems, running different key combinations: a standard Android or Blackberry system, or the encrypted system, placed in a hidden and encrypted partition.

They also have a "wiping" function, i.e. the possibility of total deletion of the encrypted system, in case of seizure by the police. The wiping can be activated directly on the phone, with a key combination, or remotely ("remote wipe"), using the network of servers on which these devices rely.

In fact, to work they rely on a network and a Mobile Device Management (MDM) platform, i.e. a system that allows you to manage multiple phones, set profiles or limitations, similar to the one used in companies. Among the most known and used MDMs there is the one based on Blackberry: this is the reason why many cryptophones use Blackberry hardware.

In summary: the security and secrecy of these phones is based on at least three levels:

  • the device and the operating system: OSs with tamper-proof systems and multiple levels of protection and access (two-factor authentication, Captcha codes, etc.) are installed;
  • connection and communications: the device connects only to the dedicated network of secure servers, it does not use non-secure public networks;
  • applications: they are dedicated apps, with strong encryption. They also have features that limit access attempts with passwords and generally have wiping functions that erase all data from the app in case of attempted violation.

Background vector created by pikisuperstar - www.freepik.com
by Silvia Mazzetta Date: 11-09-2020 privacy cryptophone hacker security hits : 13534  
Silvia Mazzetta

Silvia Mazzetta

Web Developer, Blogger, Creative Thinker, Social media enthusiast, Italian expat in Spain, mom of little 9 years old geek, founder of  @manoweb. A strong conceptual and creative thinker who has a keen interest in all things relate to the Internet. A technically savvy web developer, who has multiple  years of website design expertise behind her.  She turns conceptual ideas into highly creative visual digital products. 


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