According to Wikipedia:
TLS has a variety of security measures:
Using a message digest enhanced with a key (so only a key-holder can check the MAC). The HMAC construction used by most TLS cipher suites is specified in RFC 2104 (SSL 3.0 used a different hash-based MAC).
What hash-based MAC did SSLv3.0 use? How does it compare to the ubiquitous HMAC that is used everywhere else today?