Area authentication should be translated to JunOS interface configuration. In this IOS configuration, under the ospf hierarchy, the area 188.8.131.52 authentication apply to all interfaces in that area. There is no ospf authentication configuration under the interfaces.
interface FastEthernet0/0 ip address 172.16.23.2 255.255.255.0
ip ospf authentication-key ospf
router ospf 1
area 184.108.40.206 authentication
interface FastEthernet0/0 ip address 172.16.12.1 255.255.255.0 ip ospf message-digest-key 1 md5 ospf
Under JunOS, for md5 authentication there is a start-time option, in case you want to swap your authentication key, you could configure the start time that key will be used. Easy.
Under IOS have to be carefull. All keys are immediately used, so router send a hello for every configured key. Routers will prefer the youngest key (last configured), but it the youngest key dont match, will use all keys until this match.
If there is a configuration mismatch will be lot of authentication and key mismatch syslogs errors, for every key not configured on both sides, or not configured in the same order.
As soon the same key is configured last under the interface configuration, adjacency will become established, will prefer that key so will not use the oldest keys. But if the same youngest key is not configured in the same order, routers will use all keys, lots of syslogs msg, etc, etc.
This is the way to configure this under JunOS :
set protocols ospf area 0.0.0.0 interface ge-0/0/0.0 authentication md5 10 start-time 2012-01-21.09:00 key ospf