哪些请求标头可用于浏览器/客户端指纹？

For added security our server keeps track of the browser fingerprint. At the moment we use the following headers:

• 'HTTP_CLIENT_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR' (take the first non-empty as the client-IP)
• HTTP_ACCEPTxxxx
• HTTP_USER_AGENT

Are there any more (optional) headers that can be used?

What in general is the best 'algorithm' to calculate the client fingerprint?