About a month ago, I had to implement the KOS protocol for extending oblivious transfers. It took me a while to figure out how it worked, and a bit longer to develop an intuitive understanding. Hopefully, I can impart a bit of this intuition in this post.

Oblivious What?

Random OT

Extending OTs

Using a Seed

Correlated OT

Accounting for Cheating

Adding a Check

Conclusion