On Friday 08 January 2016 13:16:27 Niels Möller wrote:
> Tim Ruehsen <[email protected]> writes:
> > I meanwhile found the nettle docs on the web
> 
> > (http://www.lysator.liu.se/~nisse/nettle/nettle.html#MD5):
> I'm happy you found the documentation. The manual should also be
> included in debian's nettle-dev package, in info, html and pdf formats.
> 
> > ###########
> > Function: void md5_digest (struct md5_ctx *ctx, size_t length, uint8_t
> > *digest)
> > 
> > Performs final processing and extracts the message digest, writing it to
> > digest. length may be smaller than MD5_DIGEST_SIZE, in which case only the
> > first length octets of the digest are written.
> > ###########
> 
> Sorry you find this unclear. Can you suggest a concise improvement?

Never said the text is unclear. It just misses the case when 'length' is too 
large.
Citing my proposal from my previous email:
> 'If length is larger than MD5_DIGEST_SIZE the 
> function does not return - it calls abort()'

Or more precise
If length is larger than MD5_DIGEST_SIZE an assertion is generated and by that 
the program is terminated by abort(). To avoid this behavior nettle has to be 
compiled with -DNDEBUG (additional bytes will not be touched).


>     ctx = alloca(hash->context_size);
>     hash->init(ctx);
>     hash->update(ctx, length, msg);
>     hash->digest(ctx, hash->digest_size, digest);
>     return hash->digest_size;
>   }
> 
> I don't think that passing a valid digest size to hash->digest here
> should be a big deal.

Thanks Niels. This part is already up and running.
My writing was for Amos to make clear that MD5_DIGEST_SIZE and the like are 
not needed from a higher level perspective.

Regards, Tim

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