tree af037279e26f0c7ff4ac438b5cc760709e93970f
parent 71b5226ff73902d121cd9dbbdfdb67045a805845
author Eric Brown <browne@vmware.com> 1531408075 -0700
committer Han-Wen Nienhuys <hanwen@google.com> 1568020679 +0000

ssh: drop dh-group1-sha1 from default key exchanges

This removes diffie-hellman-group1-sha1 from the list of default
key exchange algorithms. This kex is considered weak and potentially
vulnerable to the Logjam attack.

Note: This is a backwards incompatible change: if you connect to ssh
servers that do not support any key exchanges except for dh-group1-sha1,
you must now specify config.KeyExchanges explicity.

See also:
https://www.openssh.com/legacy.html
https://blog.gdssecurity.com/labs/2015/8/3/ssh-weak-diffie-hellman-group-identification-tool.html

Fixes golang/go#12955

Change-Id: I032d5175d63ab5d1912de72957a80200eb396bc9
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/123595
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>