A senior cryptographer working for Microsoft has vehemently denied that the firm is planning to compromise the encryption functionality incorporated in its forthcoming Vista operating system by adding a backdoor.

Niels Ferguson, a Dutch cryptographic engineer and consultant who currently works for Microsoft, has written in his blog that there are no plans to provide a secret means for law enforcement officers to access encrypted data.

He added that, if pressure came for such a system, Microsoft engineers would either go public or withdraw the platform's encryption feature altogether.

"Over my dead body," he wrote in answer to the backdoor accusations. "Well, maybe not literally. I'm not ready to be a martyr quite yet, but certainly not in any product I work on. And I'm not alone in that sentiment. The official line from high up is that we do not create back doors."

Ferguson did say that Microsoft is answering law enforcement's questions about the new operating system, saying that the Vista key system known as BitLocker was a case in point.

Police need to know to look for all USB thumb drives as well as computers when making a raid, said Ferguson.

"Like any security technology BitLocker has its avenues of attack, and law enforcement should know about them," he continued.

Ferguson is a well respected figure within the computer community and co-wrote Practical Cryptography with Bruce Schneier.

But suspicions remain that some sort of a deal could have been done. Microsoft has been accused of shipping backdoors into Windows NT4 and 2000 that would allow the National Security Agency (or No Such Agency as it is nicknamed in Washington) to access any Microsoft system without informing senior managers.