Does mobile phone encryption software help criminals? I put that question to the creators of a new program that comprehensively scrambles phone conversations between any two handsets using it.

The products in question is Cellcrypt, a program that makes it extremely difficult (OK, impossible using current technology) to eavesdrop on mobile phone calls between Nokia/Symbian and Windows Mobile smartphones.

It's an expensive product aimed at corporates or government employees looking for confidentiality when using mobiles, but like any encryption product it can be put to use by anyone. Notice, this is not encryption only for the radio part of the transfer, between phone and base station (as is the case with GSM anyway); the encryption is end-to-end.

Do mobile phone calls matter that much? Encryption is already routinely used to secure emails, instant messaging and, more recently, Internet phone calls. The answer is yes. Mobile intercepts are regularly cited in criminal cases, and criminals probably use them more than any other form of communication for the reason that anyone uses a mobile - it is the ultimate in real time communication.

Being unable to quickly discern what is being said on a tiny but important number of phone calls could affect policing to an unknown degree.

Cellcrypt's response is to point out that any encryption technology could, in theory, benefit criminals but that these benefits are reckoned to outweigh the drawbacks.

"If we took a ‘ban it' approach we'd ban the use of the internet as well along with white vans and fertiliser," says Andy Churley.

It is obviously ridiculous to blame his company for making law potentially enforcement more difficult, but it also true that the authorities are going to have to learn how to find new ways to get phone intelligence, even as they adopt the same technologies to defend themselves.