[gnutls-devel] overall sec_param (weakest link) for a gnutls session?

[Matthias-Christian Ott]

On 01/03/14 22:03, Nikos Mavrogiannopoulos wrote:
> On 12/31/2013 12:52 AM, Matthias-Christian Ott wrote:
>> It required me to find, read and translate their documents into an OpenSSL
>> cipher list and to choose the key lengths accordingly. When new
>> recommendations are available, I would have to repeat this procedure. I
>> would prefer it if GnuTLS had a keyword BSI or something similar to
>> always conform to the latest recommendation (other systems
>> administrators I know who run TLS protected web sites don't even know
>> what a key length or a certain cipher is (sic!) and probably wouldn't
>> make any efforts to comply with the recommendations). keylength.com
>> lists other recommendations of other institutions that might be
>> relevant. Also GnuTLS already has some Suite B support.
> 
> Hello,
>  I don't know how practical it is to have priority strings for every
> possible jurisdiction. We can have though options for the major ones.

If I'm not mistaken, cipher suites only specify key lengths or symmetric
ciphers and GnuTLS security parameters are only used for key generation
not for connections. As Daniel correctly suggested, this is not enough.

At 30C3 BetterCrypto.org was presented and received some press attention
in Germany. Looking at their “Applied Crypto Hardening” document, which
targets system administrators, configuring TLS implementations is still
too hard and requires too much effort. Most administrators will never
bother.

I think we need security profiles for GnuTLS. A security profile covers
all parameters that are relevant for security including cipher suites,
key lengths and TLS extensions. GnuTLS could include some default
profiles, such as profiles based on recommendations of institutions like
NIST or ENISA. Security profiles are by default loaded from a
system-wide security profile registry (some directory consists of
security profile files) according to a system-wide security policy which
specifies the default profile. If the system administrator or
application software configures nothing else, GnuTLS uses the default
profile specified in the system-wide security policy. Configuring all
software thus in general reduces to changing a single profile name in
the system-wide security policy.

All paths for the registry, profiles and policy are of course changeable
and there will be an API to specify them programmatically instead of
loading them from files.

What you you think?

Regards,
Matthias-Christian