[TS-2392] Enable elliptic curve ciphers to support forward secrecy

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Component/s: SSL
• Assignee: Unassigned
• Reporter: Jan-Frode Myklebust
• Created: 24/Nov/13 22:50
• Updated: 18/Dec/14 05:06
• Resolved: 24/Nov/13 23:12

Description

ATS does not seem to support the elliptic curve diffie hellman ephemeral key exchanges (ECDH) that are available in openssl. It seems these needs to be enabled explicitly to take advantage of them. Ref: the following commit for how this support was added to apache httpd v2.3.3:

http://mail-archives.apache.org/mod_mbox/httpd-cvs/200911.mbox/[e-mail]%3E

and for stud:

https://github.com/bumptech/stud/pull/61/files

Maybe both a DH key exchange needs to be set up, and then the various elliptic curves needs to be initialized..?

Checking the openssl docs, I see SSL_CTX_set_tmp_dh_callback() needs to be called to set up the ephemeral keys:

http://www.openssl.org/docs/ssl/SSL_CTX_set_tmp_dh_callback.html

https://tech.immerda.ch/2011/11/the-state-of-forward-secrecy-in-openssl/

http://wiki.openssl.org/index.php/Elliptic_Curve_Diffie_Hellman

And these are the named curves available with openssl-1.0.1e-16.el6_5.x86_64 on RHEL-6.5:

$ openssl ecparam -list_curves
  secp384r1 : NIST/SECG curve over a 384 bit prime field
  prime256v1: X9.62/SECG curve over a 256 bit prime field

Issue Links

• is duplicated by: TS-2372 Add forward secrecy support (SSL related)