| From: | Neil Bothwick |
| Date: | 2 Aug 2000 at 16:46:40 |
| Subject: | Re: Programming encryption (poss OT) |
Alan Buxey said,
>> Stegography hides the encrypted text in a binary file, it could be audio
>> or graphic data. so you're not only hiding the contents of the message
>> but hiding the fact that you are hiding the contents.
> with the Amiga, we have a few ideal formats that can be used. The IFF format
> for sounds and images defines seperate HUNKs. If a program doesnt know a
> hunk-type it'll skip it. if it knows that type, it'll access and read it. so
> in a typical IFF image file, you have a header with IFF info and then the
> image chunk. all you need is a program to add the extra HUNK which contains
> the encrypted info....the image viewer views the same glorious holiday
> snapshot...the decrypter gets your real message out of it :-)
Putting the encrypted message in a hunk by itself isn't very secure.
It's the equivalent of putting the key under the doormat, far too easy
to find.
> When this was first mentioned to me...oh, about 7 years ago..i was
> interested, but it never really seemed to take off - I'd expected the Amiga
> people to have come to take this standard (since we have the best gfx and
> sound file format to use this method 100% transparently...) but it didnt
> take off.
You don't need to tie it to a format, it overwrites bits in the actual
image or sound data. That's why you have to use the type of data that
can stand minor corruption, changing a few bits in an archive or
executable would be rather destructive.
> on the PC's there is a tool called S-Tool to do the job. it works on WAVs
> and GIFs. I dont know of ANY Amiga tool :-|
As befits the topic, it's all hidden in the ;last place any Amiga user
looks... Aminet
stego.lha util/arc 48K 100+Stego encryption (68k+PPC), including source
jstegbin.lha util/crypt 145K 222+Hides secret data inside a JPEG file
jstegsrc.lha util/crypt 375K 222+Complete source for jsteg
stega.lha util/crypt 46K 227+Hide stuff in LSB of sound and gfx
stego.lha util/crypt 47K 112+Stego encryption for 68k+PPC, including source
Neil
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