Re: Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
On 29/08/2019 17:05, Hubert Kario wrote: On Wednesday, 28 August 2019 23:20:49 CEST Marcelo Lauxen wrote: ... that server is willing to negotiate ECDHE_RSA ciphers, you'd be better off disabling ciphers that use DHE and RSA key exchange and using ECDHE_RSA instead of trying to make 1024 bit work – it really is weak and should not be used (see also: LOGJAM) Where in the LOGJAM papers does it say that 1024 bit DH is too little, provided the group is not shared among millions of servers? Where, does it reliably say that ECDH with a choice of very few published groups is more secure than DH with random group parameters shared among a much smaller number of connections and servers? Also note that the following factors make it necessary to support traditional DHE for compatibility: 1. Red Hat OpenSSL builds until a few years ago disabled EC support. 2. Microsoft (and the TLS protocol specs themselves) until fairly recently allowed ECDHE only with (EC)DSA server certificates, which are not as easily available as RSA certs. 3. The "supported groups" TLS extension cannot be used without jamming the TLS clients into a short list of fixed DH groups. Thus servers have to ignore that extension and use heuristic guesses to choose the DH strength. Enjoy Jakob -- Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10 This public discussion message is non-binding and may contain errors. WiseMo - Remote Service Management for PCs, Phones and Embedded
Re: Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
* I've another question, based on your suggestion Salz Rich, this config @SECLEVEL can be set per host/domain, or is it impossible? It totally depends on which webserver you are running and what it’s configuration allows. I’m not able to answer webserver config questions BTW.
Re: Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
Thank you guys for the answers! I've another question, based on your suggestion Salz Rich, this config @SECLEVEL can be set per host/domain, or is it impossible? On Thu, Aug 29, 2019 at 12:38 PM Salz, Rich wrote: > >- We haven't control of the server who are using DH key size of 1048 >bits. > > In order to work with this kind of server (terribly poor security > characteristics), you need to add “@SECLEVEL=0” to your OpenSSL > configuration. > > >
Re: Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
On Wednesday, 28 August 2019 23:20:49 CEST Marcelo Lauxen wrote: > Our server runs with DH key size of 2048 bits and we are trying to make > requests with httparty(https://github.com/jnunemaker/httparty) to a server > that uses DH key size of 1024 bits, i want to now for what reason we are > getting this error SSL_connect returned=1 errno=0 state=error: dh key too > small, it's because different DH key sizes? 樂 > > We haven't control of the server who are using DH key size of 1048 bits. > > I've opened the same issue on httparty > https://github.com/jnunemaker/httparty/issues/664, but seems not a problem > with httparty and something with OpenSSL. > > Currently our server is using *OpenSSL 1.1.1c*, but before we was > using *OpenSSL > 1.1.0j* and this error doesn't happen. Is OpenSSL blocking the > communication between our server who uses DH 2048 bits and the other server > who uses DH 1024 bits (weak Diffie-Hellman)? If yes, is it reported in > somewhere? > > Our server SSL Labs results: > https://www.ssllabs.com/ssltest/analyze.html?d=web.monde.com.br > > Server who we are trying make requests: > https://www.ssllabs.com/ssltest/analyze.html?d=webservices.voeazul.com.br > test that server is willing to negotiate ECDHE_RSA ciphers, you'd be better off disabling ciphers that use DHE and RSA key exchange and using ECDHE_RSA instead of trying to make 1024 bit work – it really is weak and should not be used (see also: LOGJAM) -- Regards, Hubert Kario Senior Quality Engineer, QE BaseOS Security team Web: www.cz.redhat.com Red Hat Czech s.r.o., Purkyňova 115, 612 00 Brno, Czech Republic signature.asc Description: This is a digitally signed message part.
Re: Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
* We haven't control of the server who are using DH key size of 1048 bits. In order to work with this kind of server (terribly poor security characteristics), you need to add “@SECLEVEL=0” to your OpenSSL configuration.
