Subject: SSL_connect returned=1 errno=0 state=error: dh key too small
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? 🤔
We haven't control of the server who are using DH key size of 1048 bits.
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?
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)
Senior Quality Engineer, QE BaseOS Security team
Red Hat Czech s.r.o., Purkyňova 115, 612 00 Brno, Czech Republic
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
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