On Tue, Apr 5, 2011 at 03:04, Ahewd.com <[email protected]> wrote:
>
> So to rephrase the question, is it possible that the file would
> decrypt with a wrong key without throwing an exception? Or do i have
> to append some checksum of original file and then compare it to
> checksum of the decrypted file to detect if the key was good and the
> result is not just some garbage?
>

It's highly improbable, but I wouldn't be comfortable saying it's
impossible. Integrity isn't explicitly guaranteed by CBC. I'd expect a
wrong key, wrong IV or corrupt data stream to throw this exception for
CBC, and don't know of a means for distinguishing which caused it
without layering some other primitive. I'd suggest a signature and/or
an HMAC-based scheme for verifying message integrity if you need to do
that.

Geoff

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