Alex Dent

Identity Based Traitor Tracing

We consider the following natural situation: a user (with an identity) wishes to
watch an encrypted TV show being sent to a group (with a
group identity). Suppose that the user will have to pay a subscription to be
able to access the group. A trusted authority polices
membership of this group and only issues decryption keys to people who have
paid their subscription. We will show that we can easily
achieve this structure using identity-based encryption and wildcards.

However, we also want to prevent the user from selling his key off to other
people. While we cannot stop this directly, we can discourage
the user from selling his key by showing that we can trace any user who sells
his key. So if the users starts selling pirate TV boxes,
then we can recover his identity from the box and prosecute him. This is known
as a traitor tracing scheme.

In this talk we will present the first ever identity-based traitor tracing
scheme and discuss it's security results.