"Jim Lesurf" wrote:
Can anyone give me a lead for this;

As the audio comes in to drive, the stream itself needs to be encrypted
to be made tamper-proof, not just read-only. If anyone does as much as
change a meta value or cut a sample, it must ring alarm bells. (It's a
security/evidence thing)

You don't say anything about what kind of 'audio' you mean, or what kind
of
system the 'drive' is in. That might help.

Nor do you say why what you need could not be done by watermarking the
audio externally to the digital recording process. e.g. by low level ENF.

Sorry, it does not exist yet and the options would be all mine which is why
I have not specified. Due to the amount there would be, mp3 on hard disk
would be most practical.

I had thought about watermarking with a slow flanger. What is this ENF you
speak of?

'As it comes in' would have to be better defined in terms of method. You
could encyrpt on a bit-by-bit or sample-by-sample level against a
max-length sequence or similar. Or use blocks encrypted, etc. The best
choice would depend on what you want and how the system is to be used.

I'll look into that, sounds interesting.

If using a secure system like Unix/Linux then the 'admin' or the specified
user would have to 'know' the encryption keys or equivalent, or at least
have them via shadow, so you can never absolutely guarantee that evidence
has not been tampered with. All you can do is give some level of
protection
and detection. You also don't say if those using the machine to record
'audio' should also have the ability to recover the data. i.e. decrypt it.

In forensic terms 'tamper proof' is in practice a relative term, not and
absolute, and also depends on physical chain of evidence handling and the
persons involved operaing in a suitable, documented, manner.

I'm not getting far on google with this, have you been here before?

Are you a member of the AES? if so you can look at the recent papers in
JAES and conferences about 'forensic audio'. They will give you some ideas
on this, and some individuals you could contact who might advise.
Presumably if you are doing this for professional purposes you would also
be paying for any help. :-)

There is a chance I could be doing this for professional purposes in the
future, I'm looking into all the basic options first.

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