| Cryptography and Information Security Group Research Project: Self-Delegation With Controlled Propagation |
Self-Delegation
with Controlled Propagation, by Oded Goldreich, Birgit Pfitzmann, and
Ronald L. Rivest, introduce delegation schemes wherein a user may delegate
rights to himself, i.e., to other public keys he owns, but may not safely
delegate those rights to others, i.e., to their public keys. In the motivating
application, a user has a primary (long-term) key that receives rights,
such as access privileges, that may not be delegated to others, yet the
user may reasonably wish to delegate these rights to new secondary (short-term)
keys he creates to use on his laptop when traveling, to avoid having to
store his primary secret key on the vulnerable laptop. We propose several
cryptographic schemes, both generic and practical, that allow such self-delegation
while providing strong motivation for the user not to delegate rights that
he only obtained for personal use to other parties.