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Crypto phones
Secure telephones

Secure telephones are telephones that provide some level of voice security, in order to protect the calling parties from eavesdropping. Crypto phones are a special type of secure telephones that use advanced digital techniques for the encryption of voice data. Depending on the type and level of encryption used, crypto phones may be restricted or classified items.

Computer algorithms for secure voice transmission are generally controlled by the National Security Agency (NSA) in the US. They are divided into several security levels, of which Type 1 represents the highest level of security. Such devices can safely be used for top secret messages.

Secure telephones covered on this website:
Secure STU-II Motorola STU-II/B Secure STU-III Secure STE Motorola SECTEL CVAS CVAS III Philips PNVX AT&T TSD-3600
KY-68 KY-68 Philips SP-40 Philips SP-50 Racal MA-4471 The DSM Voice Siemens CS 100 Hagelin HC-3300 Hagelin HC-4220
Hagelin HC-2203 Mieco Mieco 25A

 
Voice scramblers
Older types of secure telephones generally use a technique called voice inversion. They are sometimes called scramblers and are inherently insecure. An example of such a scrambler phone is the Mieco 25A (shown above). Even voice scramblers that use time-division speech scrambling should be considered insecure by today's standards.
 
Further information

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© Copyright 2009-2011, Paul Reuvers & Marc Simons. Last changed: Tue,27 Dec 2011.17:46:24
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