how secure authentication model?

i have user comment 'member center' shows customer's subscriptions memberships have company. during .

i have another site tangible member site. during . ( any site opposite domain, nonetheless same dedicated server.

i wish yield easy login membership site, but including user's username evidence link.

so i've adult this:

when user clicks 'login' couple membership, i emanate an md5 crush userid + unix timestamp, supplement database list along userid timestamp.

i following route hash).

the login book example2 takes crush looks adult same table. crush present, i collect username evidence fan database controlling userid stored hash, pass site's pre-existing login function, logged in.

when crush login book runs, initial deletes any rows comparison 5 minutes, following checks crush value passed. finds hash, logs user in, following deletes crush used table. means there never any hashes list comparison 5 minutes. wholly there (should) any hashes left over list user somehow doesnt secure.example1.com www.example2.com after clicking couple ( say, internet goes down during only right second, dns problems solution example2.com, etc ). 5 footnote genocide means lay there reload redirected url until in, until 5 mins have left by.

when user redirected, crush value.

every login couple clicked secure.example2.com, new crush value distributed stored.

my doubt is... am i blank something obvious? smack penetrate this? i only emanate gaping confidence hole site(s)?

thanks hive mind!

edit: offer normal denote opening www.example2.com logging form controlling your username / password.

edit2: response tobyhede re: sniffing hash. assailant have also stop user reaching login book www.example2.com crush deleted once used. means stop that, following also have crush within 5 mins automatically deleted.

edit3: re: assailant generating possess hashes: hacker have insert those hashes database consolidate current userid ( users know userid ). that? given crush used wholly once following deleted immediately, i'm positive any next attacks work.