external Login and password challenge

i'm looking for a module that would allow me to do 2 things.

- verify a username/password combination is true or false (eg verify a password)
response as json
- external logon (create session for client via API (eg. log on a user) and redirect to a token-url if successful

I would also like a saml or openid logon option.
I find that this is a security risk and a weakness in my setup, and accounting details are very important and critical. If an account was compromised this would hurt a lot.