It is estimated that, in most countries where mobile communications are available, the volume of mobile communication traffic now equals that in fixed networks. As mobile traffic continues to increase, the use of fixed services is likely to become the exception rather than the rule.
This is according to Nanoteq who says that the same security risks that plague fixed line telephone network are also evident in mobile (ie GSM cellular and satellite) networks. Although the over-the-air link between a GSM handset and the basestation is encrypted, the fixed network interconnecting the basestations is the same as that of the fixed line telephone network.
Nanoteq has developed the CodeVoice Mobile, a voice encryption unit for mobile communications which can be used to encrypt voice for transmission via Inmarsat satellite networks, GSM (and other cellular) networks and the fixed line public switched telephone network (PSTN). It can, therefore, be used to communicate between mobile and fixed line networks.
Nanoteq Director Mike Venter explains the default symmetric encryption algorithm used is an international data encryption algorithm (IDEA), with a key length of 128 bits. A 1024 bit RSA-based Diffie-Hellman protocol is used to authenticate the remote user and to exchange the session keys between connected units.
"Security is achieved by converting the analog voice signal into low bit rate data, through voice compression techniques, which is encrypted before it is transferred via the mobile or satellite network. Even if the encrypted data is intercepted, it is impossible to recover the original unencrypted data and therefore the original analog voice without the cryptographic keys," he notes.
The two important elements are therefore the voice compression and the encryption. The voice compression must offer near-phone quality and caller recognition while the encryption must be standards-based and have a symmetric key length of at least 128 bits.
Venter says that with satellite communication there are even more security risks. The over-the-air link is not encrypted and due to the nature of satellite communications, they can be intercepted from anywhere within the communication footprint of the satellite. For example, some types of satellite communication can be intercepted with readily available off-the-shelf equipment.
To communicate via the Inmarsat satellite network, the CodeVoice Mobile unit is connected to an Inmarsat Mini-M terminal (satellite phone), via a serial cable. The compressed and encrypted voice is transferred via the 2,4 Kbps data channel of the satellite phone system, to the remote CodeVoice unit. In order to compress the analog voice signal to fit the 2,4 Kbps satellite phone data channel, the CodeVoice range uses a proprietary specialised vocoder that offers near-phone quality and caller recognition.
For further information contact Nanoteq, (012) 665 1338, [email protected]
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