Re: New function: secure-random-bytes

[Ted Zlatanov <tzz@lifelogs.com>]

On Fri, 24 Jun 2011 15:50:06 +0800 Leo <sdl.web@gmail.com> wrote: 

L> It seems useful to provide a way to get some cryptographically strong
L> random bytes (e.g. for uuid generation or passwords).

L> See discussion: http://thread.gmane.org/gmane.emacs.devel/138494

L> The attached preliminary patch does this. Comments are welcome. Thanks.

Do you think you could you provide three functions,
`secure-random-bytes-{urandom,gnutls,openssl}' instead of three versions
with the same name?  Then there can be a `secure-random-bytes' in
simple.el or wherever:

(secure-random-bytes) ; auto, checking with fboundp
(secure-random-bytes 'gnutls) ; try the GnuTLS version first

The nice part is that you can put `secure-random-bytes-gnutls' in
gnutls.c; make openssl.c for `secure-random-bytes-openssl' and use a
HAVE_OPENSSL ifdef; and put `secure-random-bytes-urandom' in fileio.c
inside a HAVE_URANDOM ifdef.  That will avoid making up numeric
constants for SECURE_RANDOM_TYPE in favor of more meaningful constants
and puts all the new functions in the right place.

I can imagine other uses for the OpenSSL functions, so at least the
HAVE_OPENSSL macro makes a lot of sense.

I'm not sure what the auto priority should be.  Are the GnuTLS/OpenSSL
functions better than /dev/urandom?  They are certainly slower.

Thanks
Ted