New Application for FPE – VoIP

There has been a lot of attention over the past few months on how Format Preserving Encryption (FPE) can be applied to secure end to end encryption of credit card payments, but FPE also has applicability in other areas, for example I recently heard of a novel use of FPE for VoIP systems.   

While it is clear that IBE could be used to secure the Session Initiation Protocol (SIP) by using the Request-URI as the identity, IBE could not be used for securing the Real-time Transport Protocol (RTP) stream.  This is where FPE comes in.

From my last blog post one can see how you can encrypt, say, a street address to another street address using regular expressions.  This new application of FPE is similarly used to encrypt the voice stream of a VoIP call.

In this new use of FPE a spoken noun is encrypted to another spoken noun, a spoken verb to another spoken verb etc.  

The receiver of the voice stream can then decrypt to the original voice stream.

For example:   Alice, call originator, wants to leave a critical voice message for Bob.   
She speaks the phrase “Bob, the iPad is delayed by a critical hardware error, short Apple stock”,
but using FPE in this new mode the message is left in Bob’s voicemail as:  “Bill, the iPhone is on-time because of excellent software, buy AT&T stores”

Rather than use regular expressions, this new method uses something called irregular expressions.  We hope to make it available in the upcoming 4.1 release of the Voltage Encryption Toolkit.

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