Welcome to the resource topic for
**2001/059**

**Title:**

Revocation and Tracing Schemes for Stateless Receivers

**Authors:**
Dalit Naor, Moni Naor, Jeff Lotspiech

**Abstract:**

We deal with the problem of a center sending a message to a group

of users such that some subset of the users is considered revoked

and should not be able to obtain the content of the message. We

concentrate on the stateless receiver case, where the users

do not (necessarily) update their state from session to session.

We present a framework called the Subset-Cover framework,

which abstracts a variety of revocation schemes including some

previously known ones. We provide sufficient conditions that

guarantee the security of a revocation algorithm in this class.

We describe two explicit Subset-Cover revocation algorithms; these

algorithms are very flexible and work for any number of revoked

users. The schemes require storage at the receiver of \log N and

\frac{1}{2} \log^2 N keys respectively (N is the total number

of users), and in order to revoke r users the required message

lengths are of r \log N and 2r keys respectively. We also

provide a general traitor tracing mechanism that can be

integrated with any Subset-Cover revocation scheme that satisfies

a ``bifurcation property’'. This mechanism does not need an a

priori bound on the number of traitors and does not expand the

message length by much compared to the revocation of the same set

of traitors.

The main improvements of these methods over previously suggested

methods, when adapted to the stateless scenario, are: (1) reducing

the message length to O(r) regardless of the coalition

size while maintaining a single decryption at the user’s end (2)

provide a seamless integration between the revocation and

tracing so that the tracing mechanisms does not require any change

to the revocation algorithm.

**ePrint:**
https://eprint.iacr.org/2001/059

See all topics related to this paper.

Feel free to post resources that are related to this paper below.

**Example resources include:**
implementations, explanation materials, talks, slides, links to previous discussions on other websites.

For more information, see the rules for Resource Topics .