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Company Makes Inconspicuous Secure Cellphone
dponce80 writes "With concerns over privacy at an all-time high, it's refreshing to hear that Swiss company VectroTel is making a secure mobile phone. The X8 encrypts secure calls (the unit is also able to make regular calls) with a virtually unbreakable 128-bit key, itself generated through a Diffie-Hellman exchange. While transmission does get somewhat delayed, communication is secure."
Swedish plasma phys. PhD student; MSc EE; knows maths, programming, electronics; finance interest; seeks opportunities
Cryptophone is a company that has been making phones like this for some time already.
They employ some of the smartest crypto people, use well-known algorithms and publish their sources so you can check them yourself.
Reading the comments made me cringe, so here goes....
Some points;
- 128 bit keys are probably good enough, depending on the nature of the conversation. Diffiehellman generates a per-session master secret. To this you would then apply a KDF ( Key Derivation Function ) in order to produce your session key for use with your symmetric cipher, most likely AES or 3DES, maybe even TwoFish. A new master secret is generated every time you make a call, hence the session key changes per call, this is UNLIKE your WEP key, which is constant or one value selected from a set. The consequence of this is that although it is practical to break an 128 bit symmetric key, it is NOT practical to do so in the time interval in which the call is taking place. Hence the encryption applied is strong enough for protecting calls in the short term, although if someone captured the call they could possibly decrypt it at a later date.
- GSM does feature limited cryptography. Unfortunately, and rather amusingly this encrypting is only carried out on radio traffic. Once the data reaches the base station / cell, it is sent in the clear around the cable cellular netork's backbone infrastructure.
Not quite. The 900 and 1800MHz bands are used by different service providers. In the UK, 900MHz is used by Vodafone and O2, and 1800MHz is used by Orange and T-Mobile. Before the advent of the venerable Nokia 3210, most phones were single-band and were built using two PCBs: one for the main processor, audio circuitry, keypad and display, and one for the RF stuff {which would be made in 900 and 1800 versions and the phone assembled accordingly}. The 3210 used a single PCB capable of doing both RF bands. The cost saving associated with the single-board design {no expensive multiway connectors, and a better process hit rate} outweighed the cost of the extra components.
A phone connected to a base station will always us one or the other band. But within each band there are several channels; the phone and base station automatically select the best channel continuously throughout a call {if another subscriber disconnects and the channel they were using is better, your conversation will switch to that channel}. The whole process is kept seamless because both phone and base station change at the same time, between data packets.
Je fume. Tu fumes. Nous fûmes!
A Swedsh company called Sectra has made secure cellphones for years. Their latest model is the only cellphone certified to the security level NATO SECRET by NATO.
t ion/sectra/
http://www.army-technology.com/contractors/naviga
Martin
This is how it's supposed to work: Alice calls Bob. Bob answers. Alice generates a key pair and sends one of the keys to Bob, keeping the inverse. Bob also generates a key pair and sends one to Alice, keeping the inverse. Alice encrypts everything she sends against the key she received from Bob. Bob decrypts it using the inverse key he generated. Bob sends everything to Alice encrypted against the key Alice sent him. She has the inverse key and can decrypt everything Bob sends.
All clear now? Well, this is how it might work in practice, with a malicious interloper we'll call Mallory:
Alice tries to call Bob. Mallory intercepts the call, pretending to be Bob; gets the key Alice sends, and in return sends her a key {which Alice thinks is from Bob}. A fraction of a split second later Mallory places a call to Bob, pretending to be Alice, and sends Bob a key. Bob thinks Mallory's key is really Alice's key and sends a key to "Alice". Whatever Alice says is encrypted against the key sent to her by Mallory, who -- having the opposite key -- can decrypt it, re-encrypt it against the key which Bob has, and send it on to Bob. Mallory has a nice, fast computer that can do decryption and re-encryption in real time; in reality, it only has to be twice as fast as the processor in either of their telephones. Whatever Bob says is encrypted against a key sent to him by Mallory, who can decrypt it and re-encrypt it against Alice's key. Mallory has both sides of the conversation, in the clear, and neither Alice nor Bob are any the wiser.
Je fume. Tu fumes. Nous fûmes!