Which one is more general, attribute based encryption or inner product predicate encryption?

Question

1. If we have a scheme for inner product predicate encryption (IPPE), then can we claim that we already have designed an attribute based encryption (ABE) scheme; So we do not need to design an ABE again. I mean, is IPPE more general than ABE?
2. What about predicate encryption (PE)? I think PE is more general than ABE, Right?

Answer 1

We should consider two things:

• public/private index (attribute)
• expressiveness of the access strucrure

We can look at IPPE as ABE with hidden indices for access structures represented by inner product of two vectors. So IPPE is a special case of ABE with hidden indices.

In PE, indices (i.e. attributes) are hidden, and we also need different security model; simulation-based security instead of indistinguishability-based security. (It can be shown that there are PE schemes which are IND-secure but aren't SIM-secure)

So, IPPE is a subclass of ABE with hidden indices, and ABE is a subclass of PE.