Encryption of cell phone talks

Encryption of cell phone talks

Stories of development of means of transfer and protection of the information go hand in hand. The invention of radio allowed to transmit information almost instantly over huge distances, but completely crossed out the possibility of using old encryption methods. It is one thing when a secret letter with mysterious symbols and wax seals travels for months in a messenger’s saddlebag, but the information is still relevant.

It is quite different when the operational situation changes within a few hours, and there is no time to wait for one specially trained person to encode the urgent information, and the other person will transfer it, the third person will receive it, and the fourth person will open the code.

Progress in data transmission inevitably pushes the development of security features. To date, the most rapid and accessible channel of communication is telephone, but telephony is also different. The essence is the same, but the implementation and technology are completely different. So what do information technologies offer us in the field of protection and privacy of conversations? 

Let’s go! Internet Protocol (IP)

1) Data transfer in IP-networks (Internet), where data are transmitted in disparate packets, and the amount of simultaneously transmitted information is so large that to collect it together for each user is an unrealistic task. Such networks use IP-telephony – a combination of the latest technologies, users of which do not depend on the city telephone networks.

2) IP-telephony – it’s easy to use, flexible configuration and saving money on long distance and international calls. Implementation of IP-telephony will allow to control (monitor, record, listen to) all telephone conversations of subordinates.

3) Optional Transport Layer Security Connections (TLS) and Secure Transfer Protocol (SRTP) are designed to provide:

    • protect the call from tapping by encrypting the call;
    • Prevent the interception of all or part of the conversation;
    • no unauthorized connection to the system;
    • reliability and integrity of all data transmitted in the system.

Find out more about IP Telephony Protection here.

The same package technology of data transfer via IP protocol is used in mobile networks via GPRS, EDGE, 3G, 4G (high speed – the volume of transferred and received information is charged). In this regard, it is possible to recommend the organization of secure mobile communications based on modern smartphones with installed voice over IP protocols in GSM networks (Skype, Google Talks). Of course, such a solution does not give absolute confidentiality (special services can always get access to information on official request), but to resist commercial espionage this solution can be quite successful.

4) Optionally, the intruders can find some careless employee of the operator company and pay him to listen to the already decrypted conversations through switches. These mobile interceptors can be protected by phone conversation encryption programs.

5) To use encryption software, you will need a modern smartphone and the more powerful it is, the better – real-time encryption with long keys takes up a lot of system resources, so the device will have to work under heavy load. Obviously, ordinary cell phones with Java-machine-based programs will not cope with the intensive flow of calculations.


6) The list of software tools opens one of the most popular encryptors, called Cellcrypt Mobile, born in Britain. The program with a nice interface should be installed on both phones, on which you will be talking. The exchange of encrypted data in this case occurs through the CSD channel, that is, you call as if from the modem to the modem. In addition, the software successfully works through a connection with packet data transmission (GPRS, EDGE, UMTS, HSDPA, EV-DO), as well as through Wi-Fi – however, in these cases you will have to pay for the traffic and not for time.

7) For signal encryption in Cellcrypt uses an algorithm AES with 256-bit key and the corresponding checks for integrity. The developer promises a very reliable, clear voice communication without interference and loss of fragments – even the military can use Cellcrypt Mobile. The program has passed the tests for compatibility with mobile networks, received FIPS 140-2 security certification in the U.S. and is available for owners of Nokia smartphones based on Symbian and advanced cell phones of the Canadian company RIM Blackberry.

8) As a nice addition, the latest version of Cellcrypt Mobile has learned to make secure calls via satellites with the same smartphones Nokia and BlackBerry. All you need for such a call is a broadband terminal with access to the satellite. The subscriber will be able to receive a call from the satellite to his cell phone with pre-installed application Cellcrypt. The price of the question is £500.


9) Very inexpensive SecureGSM software is designed for use with cell phones running the Microsoft Windows Mobile operating system – the developers’ portfolio has versions for devices with touch and conventional displays.

10) The program allows you to make confidential telephone conversations and send encrypted text messages over the CSD data channel in cellular networks, providing effective two-way protection against eavesdropping and interception of messages. You can see a list of supported smartphones on the developers’ website.

11) SecureGSM uses reliable 256-bit encryption based on three algorithms at once – AES, Two sh, Serpent. None of these algorithms can be decrypted at the moment. Secret and public keys are generated for only one message session and are destroyed at the end of the connection. On the caller’s side, verification procedures are performed to ensure that the information being transmitted is safe and unchangeable. In the crypto community, such protection measures are called “paranoid”, and the developer promises ideal voice quality.

12) SecureGSM will cost $600-850, wishing to buy a device with already installed software for $ 1600-1800 (HTC Touch II, HTC S730 and others).


13) Cryptogic software is a representative of the class of inexpensive encryption tools. Utility for Nokia smartphones based on Symbian operating system (3rd, 5th Edition) costs only €100.

14) The application is tightly integrated with the smartphone operating system, allows you to make well encrypted calls between two cell phones (yes, both will have to install Cryptogic). The AES algorithm with 256-bit key is used for voice encryption, while the DES algorithm is used to transfer secret data.

15) It will take years to crack the selected encryption methods, unless, of course, a multimillion IBM Roadrunner supercomputer is at hand. In other words, it is almost impossible to crack the algorithm. The ability to work with HSCSD protocol provides the best voice quality for encrypted calls. However, it is not usually supported on our networks. The downside is that the program does not support encryption of text messages, but at such a price…


16) For those who do not need to encrypt conversations, but would like to protect precious SMS from the eyes of others, there are simple clients for encrypting messages. Take, for example, SafeTxT is a free application for smartphones running Symbian. The functionality of the program allows you to send and receive encrypted SMS, encrypt a book with contacts and personal notes. All data will be available only after entering a password.

17) The encryption uses advanced algorithms AES and RC4 (the developers call them “army level algorithms”). As a nice addition, the program allows to erase all data stored on your smartphone remotely.

18) Another compact Java program for text message encryption is CryptoSMS. Unlike SafeTxT, it provides archiving of sent SMS so that the user does not have to pay for a message of double size (encryption algorithms greatly inflate the file size).

19) Finally, the completely free open-source SMS Salama program offers to send messages with a password known only to two subscribers. In addition, the program encrypts the contact list.


WARNING! All links in the articles may lead to malicious sites or contain viruses. Follow them at your own risk. Those who purposely visit the article know what they are doing. Do not click on everything thoughtlessly.


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