How to Implement security in wcf rest service?

Inherit UserNamePasswordValidator class to your own class and override the "Validate" method. Some configuration will be required in web.config.

Please follow the link below. http://www.c-sharpcorner.com/UploadFile/vendettamit/create-secure-wcf-rest-api-with-custom-basic-authentication/

Use Token based authentication by using encryption and decryption like AES , RSA Etc. It Basically message level security there is another type of security IE: transport level