Once upon a time, there was a Solaris 10 box where I wasn't able to use ssh keys to login.

Thankfully, that time has now passed. The problem was because PAM was denying access with public keys.

Running sshd in debug mode (-ddd) I would see this:

Found matching DSA key: 80:aa:32:03:ef:51:9c:7b:0f:1d:ac:37:17:d5:fd:2b
debug1: restore_uid: 0/0
debug1: ssh_dss_verify: signature correct
debug2: Starting PAM service sshd-pubkey for method publickey
debug3: Trying to reverse map address 69.181.132.53.
debug2: userauth_pubkey: authenticated 0 pkalg ssh-dss
Failed publickey for psionic from 69.181.132.53 port 55957 ssh2

Clearly indicated here, is the fact that it accepted my ssh-dss key, but I failed for some other reason. Listed here, is: Starting PAM service sshd-pubkey for method publickey. Solaris 10's manpage for sshd shows that it uses different PAM service names for each type of authentication.

The solution involved adding a simple service entry in /etc/pam.conf:

sshd-pubkey    auth required           pam_unix_cred.so.1

It works now. This takes effect immediately as the pam config is invoked any time sshd uses pam, so you don't have to restart sshd.