The best replacement for authentication is authorization.

The best alternatives to authentication are rated as following:
★★★★★  authorization
★★★  identification
★★★  authentification
★★★  notarization
★★  apostille
★★  encryption
★  sql server authentication
★  authenticity
★  authorisation
★  shared key
★  mixed mode
★  ntlm
★  windows authentication
★  verification
★  sql authentication
  access control
  non-repudiation
  authentication
  foundation
  chap authentication
  notarization application form
  shared
  validation
  mutual group authentication
  non repudiation
  authorization asp net
  authorization asp.net
  digital signature
  kerberos
  apostille certificate
  chap

Your alternative for authentication is not listed? Suggest!
Speaking about authentication, one probably shouldn't forget about ssl.

Other search terms related to authentication and their ratings are:
★★★★★ ssl
★★★★ session
★★★★ ldap
★★★★ encryption
★★★ curl
★★★ authorization
★★ login control
★★ https
★★ rest api
★★ web api
★★ username
★ apache
★ kerberos
★ pki
radius
server connection
membership provider
devise
You have in mind a companion for authentication and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of authentication in all years. Click on graph for more.
authentication
authorization
identification