[vorbis-dev] Will Vorbis happily decode packets with random data?

[Monty]

On Wed, Aug 08, 2001 at 12:16:58PM -0400, Martin C. Martin wrote:
> Hi,
> 
> For my application there's been some talk of people hiding viruses in
> Vorbis files.  While the possibility's remote, I'm exploring ways to
> verify that a give file really is a Vorbis file, and doesn't even have
> long streaches of executable code in the middle of it.
> 
> If a file has valid Ogg page structure, and a valid Vorbis header, but
> somewhere in the file a packet has been replaced with arbitrary data
> (say Windows executable code), will the decoder notice this?  

If the random data was inserted into a file after it was generated,
the affected page will be rejected.  The checksum on the page will
fail.  If it was added between pages or after the stream, it will also
be rejected.

If the random packet was inserted into the stream at generation time
(and fed through the paging/checksumming mechanism within Corbis), it
might get as far as decode, but will possibly still get kicked bad.
Worst case, it will decode as noise.

Monty

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.