# How to set Elliptic-curve Diffie–Hellman curve?

**URL:** <https://discuss.elastic.co/t/how-to-set-elliptic-curve-diffie-hellman-curve/197736>\
**Category:** Elasticsearch\
**Tags:** elastic-stack-security\
**Created:** [September 2, 2019, 8:03pm UTC](https://discuss.elastic.co/t/how-to-set-elliptic-curve-diffie-hellman-curve/197736 "2019-09-02T20:03:47Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![vklimovs](https://avatars.discourse-cdn.com/v4/letter/v/c2a13f/32.png) [@vklimovs](https://discuss.elastic.co/u/vklimovs)\
**Post date:** [September 2, 2019, 8:03pm UTC](https://discuss.elastic.co/t/how-to-set-elliptic-curve-diffie-hellman-curve/197736/1 "2019-09-02T20:03:47Z")

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Setting cipher suite is possible using xpack.security.transport.ssl.cipher\_suites, for example:  
xpack.security.transport.ssl.cipher\_suites: TLS\_ECDHE\_ECDSA\_WITH\_AES\_128\_GCM\_SHA256

but there appears to be no setting to control the elliptic curve used for ephemeral Diffie–Hellman exchange. Is that correct or I am missing something?

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**Author:** ![ikakavas](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ikakavas/32/34430_2.png) [@ikakavas](https://discuss.elastic.co/u/ikakavas)\
**Post date:** [September 9, 2019, 2:31pm UTC](https://discuss.elastic.co/t/how-to-set-elliptic-curve-diffie-hellman-curve/197736/2 "2019-09-09T14:31:00Z")

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Hello,

As far as I know, there is no way in JSSE to set the preferred values for the `supported_groups` extension that is used in the TLS 1.3 ( or `elliptic_curves` as it used to be called in TLS 1.2 ) handshake to denote this.

You can probably set this as a JVM property in `jvm.properties` using the `jdk.tls.namedGroups` system property that is available since 8u21. Note that setting this will not only affect ECDHE but also ECDSA too.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [October 7, 2019, 2:35pm UTC](https://discuss.elastic.co/t/how-to-set-elliptic-curve-diffie-hellman-curve/197736/3 "2019-10-07T14:35:59Z")

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