On Thursday 07 January 2016 13:26:37 Niels Möller wrote:
> Tim Ruehsen <[email protected]> writes:
> > just experienced a crash (assertion) when using md5 on short input.
> >
> > test: md5.c:81: nettle_md5_digest: Assertion `length <= 16' failed.
> >
> > The code is
> >
> > struct md5_ctx md5;
> > md5_init(&md5);
> > md5_update(&md5, "moin", 4);
> > md5_digest(&md5, 20, digest);
>
> ^^
>
> The problem isn't the *input* length, but the output length.
> The length argument for md5_digest can be at most MD5_DIGEST_SIZE, i.e., 16.
When walking back from lunch everything sorted out in my brain. I was too
hungry when I wrote that text. Sorry for the noise.
But what's wrong with providing a larger buffer than needed ?
Imagine snprintf would throw an assertion if the provided buffer is 'too
large'.
> Asserts in nettle are triggered when bugs in nettle or in the
> application violate necessary assumptions required for correct
> operation. In most cases, an immediate crash is preferable to follow on
> problems such data corruption or invalid memory accesses. Right, I know
> there are some exceptional production systems (e.g, the Ariadne
> rocket...) where it *might* be preferable to ignore problems and hope
> for the best, and I also know there are different opinions. But my view
> is that in general, it makes sense to keep asserts also in production
> code.
Some admins have their jobs due to 'stop-by-assertion' software - at least
that is good thing about assertions ;)
Best Regards
Tim
_______________________________________________
nettle-bugs mailing list
[email protected]
http://lists.lysator.liu.se/mailman/listinfo/nettle-bugs
