SSL Server setup DH/ECDH
matt at openssl.org
Tue Aug 6 10:23:24 UTC 2019
On 06/08/2019 11:21, Chitrang Srivastava wrote:
> Yes , since in my case mostly browser will be used to access webserver running
> on embedded platform.
> Another question, since my webserver is running on embedded platform and it has
> limited memory , I have disabled
> ARIA/CAMELLIA and few others, is that OK ? because I don't see any ciphers
> suites which is used in practice.
Yes, that should be fine.
> On Tue, Aug 6, 2019 at 3:42 PM Matt Caswell <matt at openssl.org
> <mailto:matt at openssl.org>> wrote:
> On 06/08/2019 11:07, Chitrang Srivastava wrote:
> > Thanks Matt,
> > So now I have, which i believe is enough ?
> > SSL_CTX_set_options(s_ctx, SSL_OP_NO_RENEGOTIATION |
> > SSL_OP_CIPHER_SERVER_PREFERENCE);
> > SSL_CTX_set_min_proto_version(s_ctx, TLS1_2_VERSION);
> This is fine although it obviously prevents connections from very old clients
> that don't support TLSv1.2. This might not be a problem for you depending on
> your situation.
> > On Tue, Aug 6, 2019 at 3:04 PM Matt Caswell <matt at openssl.org
> <mailto:matt at openssl.org>
> > <mailto:matt at openssl.org <mailto:matt at openssl.org>>> wrote:
> > On 06/08/2019 09:42, Chitrang Srivastava wrote:
> > > Hi,
> > >
> > > I am implementing HTTPs server using openssl 1.1.1b.
> > > Is it mandatory to setup these API's while creating ssl context ?
> > >
> > > SSL_CTX_set_tmp_ecdh
> > >
> > > SSL_CTX_set_tmp_dh
> > By default OpenSSL will automatically use ECDH if appropriate and choose a
> > suitable group so there is no need to call SSL_CTX_set_tmp_ecdh()
> unless you
> > want more control over which specific group is used.
> > OpenSSL will not use DH unless you specifically configure it. If you
> want to
> > make use of DH based ciphersuites then you must either call
> > or SSL_CTX_set_dh_auto() (or the SSL_* equivalents). Calling the
> former enables
> > you to configure any arbitrary DH group that you choose. Calling the
> latter will
> > enable the built-in DH groups.
> > It is not mandatory to call any of the above.
> > >
> > > Also any suggestion what all options one should set while setting up
> > server like
> > > SSL_CTX_set_options like SSL_OP_NO_SSLv2 |SSL_OP_NO_SSLv3
> > Don't use the protocol version specific options at all. Use
> > SSL_CTX_set_min_proto_version() if you want to specify a minimum protocol
> > version. SSLv2 is no longer supported at all. SSLv3 is compiled out by
> > Other options that are worth considering are SSL_OP_NO_RENEGOTIATION and
> > (possibly) SSL_OP_CIPHER_SERVER_PREFERENCE. Generally you don't need
> the others
> > unless there is a specific problem you are trying to solve.
> > Matt
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