Crypto Voice over Skype and Viber

With the use of IP telephony mobile applications voice and data is transmitted over open channels of the Internet an can be intercepted or fabricated.

Even if the developers of IP telephony mobile claim to encrypt and protect data, initial data is stored on users’ mobile devices in its initial form and voice channel can be controlled by criminals by hacking into a mobile phone with viral software.


This is the reason why the solution we offer, Crypto Voice Over IP, is implemented in a separate hardware encryption device – Stealthphone Hard, manufactured in accordance with TEMPEST, that exchanges encrypted data with the phone. Voice and data is encrypted in Stealthphone Hard by super strong cryptographic algorithms, guaranteeing safety and confidentiality of data.

Voice encryption algorithms for IP telephony software

When IP telephony applications are utilized, including Skype and Viber, guaranteed security time-frequency transformation of the voice signal provides the protection of voice information and converts the speech into a noise-like signal.

The transformation consists of:

  • N-filter comb (a filter bank)

  • Dispersive delay line (a filter with random phase-frequency characteristics)

  • N-length substitution

The transformation properties (the number of filters, the delay line parameters) depend on the key.

The repositioning of the spectral bands in a filter comb is set by the session key once the connection is established.

The bands are rearranged once every 3-5 seconds to execute a dynamic transformation.

The algorithmic time delay does not exceed 1 second. The band of the processed voice signal is 300-3400 hz. The minimum length of N substitution is 24.

There may be several transformations depending on the traffic capacity of Internet connection. The permitted extreme delay is 2 seconds. If Internet connection is slow or unstable, an algorithm, that does not require synchronization, may be used. It provides quick handshaking and stable cryptographic connection.