[Pkg-gnutls-maint] Bug#416717: libgcrypt11-doc: not happy with documentation

[Werner Koch]

On Fri, 30 Mar 2007 01:43, jdorje at users.sf.net said:

> There is a one-line description of each function, but no description of how
> things actually work or are intended to be used.

You may want to write such docs and contribute them.  In the meantime
GnuPG 2.0 is a good example on how to use Libgcrypt.

> * If I use gcry_randomize, do I need to use gcry_random_add_bytes within
>   the same program?

No, it is just planned for adding addditional entropy:

   Add BUFLEN bytes from BUF to the internal random pool.  QUALITY
   should be in the range of 0..100 to indicate the goodness of the
   entropy added, or -1 for goodness not known. 

   Note, that this function currently does nothing.

> * If I use gcry_randomize too much and run out of entropy, what happens? Will
>   it block?  Or do I get sucky random numbers?

It will block.  However this is only an issue if you request
GCRY_VERY_STRONG_RANDOM.

> * How much less random are the values returned by gcry_create_nonce?  For
>   what applications might I use them instead of gcry_randomize?  And if
>   gcry_randomize never blocks, why shouldn't I always use it?

A nonce is something different.  Please read the the cryptographic
literature to learn what a nonce is.

> By testing a few things it appears as though gcry_randomize always accesses
> /dev/urandom for its entropy.  Thus on my system it never blocks but may

The SVN trunk of random.c is much better commented; you might want to
read it.



Shalom-Salam,

   Werner