On 22/05/15 11:11, Nayna Jain wrote: > Hi, > > With the latest logjam attack, as I was trying to verify if my server > (lighttpd) accepts DHE_xxx ciphers, I saw that it accepted and I > didn't do any configuration setting done for DH parameters explicitly. > > But I couldn't verify what is the key length did it use by default > 512/1024/2048 ? > > Eg. the one it negotiated was DHE-RSA-AES128-SHA256 and for TLSv1.2 > protocol ? > > Will the key length be different for different protocols like > SSLv3/TLSv1.0/TLSv1.1/TLSv1.2? If yes , then what for each of them. How that is configured depends on the application that is using OpenSSL. A quick google search throws up this: http://redmine.lighttpd.net/projects/1/wiki/docs_ssl 'Diffie-Hellman and Elliptic-Curve Diffie-Hellman parameters Diffie-Hellman and Elliptic-Curve Diffie-Hellman key agreement protocols will be supported in lighttpd 1.4.29. By default, Diffie-Hellman and Elliptic-Curve Diffie-Hellman key agreement protocols use, respectively, the 1024-bit MODP Group with 160-bit prime order subgroup from RFC 5114 and "prime256v1" (also known as "secp256r1") elliptic curve from RFC 4492. The Elliptic-Curve Diffie-Hellman key agreement protocol is supported in OpenSSL from 0.9.8f version onwards. For maximum interoperability, OpenSSL only supports the "named curves" from RFC 4492. Using the ssl.dh-file and ssl.ec-curve configuration variables, you can define your own set of Diffie-Hellman domain parameters. For example: ssl.dh-file = "/etc/lighttpd/ssl/dh2048.pem" ssl.ec-curve = "secp384r1"' Matt
