Google Security Engineer interview questions

I was first contacted by a Google technical recruiter from my resume in Dice.com. After the initial screening a technical phone interview was scheduled. The technical interview consisted of a number of CS questions (describe a TCP handshake, what is sorting algorithm X) followed by security-related questions (what is a buffer overflow, what is an HMAC, what are common web site vulnerabilities). I answered every question well, but blanked on the finer details of HMAC and was not moved on to the next round.