REST Service design for Authentication
===

I want to design REST service for authentication and account management. Please let me know whether the following satisfies the REST style.

    POST http://server/security/authenticate?username=xxx&password=yyy
    POST http://server/security/forgotPassword?username=xxx&email=yyy
    PUT  http://server/security/changePassword?oldPassword=xxx&newPassword=yyy

Whether HTTP methods POST & PUT are right here? Since authentication doesn't modify anything, is it better to use GET here? I am confused.