[gnutls-help] 3.6.7 interoperability problems with earlier 3.6.x

Andreas Metzler ametzler at bebt.de
Mon Jun 10 15:02:38 CEST 2019

On 2019-06-10 Nikos Mavrogiannopoulos <nmav at gnutls.org> wrote:
> On Sun, Jun 9, 2019 at 11:39 AM Andreas Metzler <ametzler at bebt.de> wrote:

Hello Nikos,

>> If you can think of specific changes in 3.6.8 that you think I should
>> cherry-pick I would be very grateful. Perhaps #720 (IDNA)?

> On the important bugs bucket I'd put the streebog fix, and the
> gnutls_srp_set_server_credentials_function fix for 8192 parameters.
> These two can cause serious issues to applications that use this
> functionality but which were tested with the new release of gnutls,
> but run on debian.

That is c1441665abe761536b3ed67d36b12f2198be6b12 and

> The fix "Fixed bug preventing the use of gnutls_pubkey_verify_data2()
> and gnutls_pubkey_verify_hash2() with the
> GNUTLS_VERIFY_DISABLE_CA_SIGN flag (#754)", I think fits into the
> previous bucket as well though its impact may be lower (fewer
> applications using this flag).


BTW: Afaict the respective test in the followup patch
1d3452d69670e28edfcaa232847036f600bbe1e8 is never run,
tests/sign-verify-data-newapi.c tests/sign-verify-newapi.c does not seem
to be referenced in any Makefile.

> The "Apply STD3 ASCII rules in gnutls_idna_map() to prevent
> hostname/domain crafting via IDNA conversion (#720)" is a security
> hardening measure to prevent potential problematic hostnames. I'm not
> aware of any exploitation under TLS/PKIX, though that doesn't mean
> that it cannot.


> The "During Diffie-Hellman operations in TLS, verify that the peer's
> public key is on the right subgroup (y^q=1 mod p), when q is available
> (under    TLS 1.3 and under earlier versions when RFC7919 parameters
> are used)." is another security hardening measure that is due to NIST
> requirements (there is no IETF guidance afaik) however it makes sense

That would be 2555412f8982ec0a1bbbf6b3c10a0330fe848820 to
e07061b29a75ff94f0dbf85ec44f7ad6c04761fa? i.e. this would include
addition of gnutls_dh_params_import_raw3() and gnutls_ffdhe_????_group_q?

TIA, cu Andreas

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