SECURITY SEMINAR SERIES
| Title: |
Questioning the Usefulness of Identity-based Key Cryptography |
| Speaker: |
Yvo Desmedt, UCL |
| Date: |
Tuesday, 23 November 2004, 16:15 |
| Place: |
Lecture Theatre 2, William
Gates Building |
Abstract:
Since Boneh-Franklin's 2001 paper on "Identity based encryption from the Weil
pairing," the research on identity based cryptography and the work on
applying bilinear maps to cryptography are both flourishing. Shamir, in 1984,
proposed the idea of "identity-based" cryptography to avoid a Public Key
Infrastructure. Instead of having the users have their own public key, the
identity of the user is the "public key," and a trusted center provides each
party with a secret key.
We critically analyze whether Shamir's identity-based concept allows us to
avoid a public key infrastructure. We argue the need for at least a
registration infrastructure, which we call a "basic Identity-based Key
Infrastructure." Moreover, we demonstrate that, if secret keys of users can
be stolen or lost, the infrastructure required to deal with this is as complex
as the one of PKI. Our discussion extends to the case the traditional PKI is
replaced by an on-line PKI, as introduced by Rivest (1998).
We conclude by surveying possible useful applications of identity-based
cryptography. Note: no number theory will be used in this lecture.
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