Spit out a random e-mail address and record which e-mail address was given to each IP.
The author mentions it’s a violation of GDPR to record visitors’ IP addresses. I’m not sure that’s correct, but even so, it could be possible to make a custom encoding of literally every ipv4 address through some kind of lookup table with 256 entries, and just string together 4 of those random words to represent the entire 32-bit address space, such that “correct horse battery staple” corresponds to 192.168.1.100 or whatever.
The author mentions it’s a violation of GDPR to record visitors’ IP addresses. I’m not sure that’s correct, but even so, it could be possible to make a custom encoding of literally every ipv4 address through some kind of lookup table with 256 entries, and just string together 4 of those random words to represent the entire 32-bit address space, such that “correct horse battery staple” corresponds to 192.168.1.100 or whatever.
What you’ve described is often referred to as a rainbow table and is generally not considered to be GDPR compliant:
https://skymonitor.com/why-hash-dont-anonimize-an-ip-address-and-what-this-affects-gdpr/