Hidding Attributes in ABE: DIPPE (Decentralized Inner-Product Predicate Encryption)

With Attribute-Based Encryption (ABE) [2], we allow users with certain attributes to decrypt data. This might relate to their location or their rights to log into a network. Two key features of this are to provide multiple authorities in providing the attributes (multi-authority — MA-ABE) and in hiding the access policy used. With DIPPE (Decentralized Inner-Product Predicate Encryption) [1], we can perform both multi-authority provided attributes, and also access policy hiding. This provides a decentralised approach to ABE.

For policy hiding, DIPPE uses a decentralized inner-product predicate encryption scheme, where we have a policy vector and a user vector that is orthogonal. For this, their inner product should be zero.

If we have two vectors of u and v, then they are orthogonal if their inner product is zero:

⟨u,v⟩=0

For example, if we have:

Thus:

⟨u,v⟩=(0×1)+(−1×1)+(1×1)+(0×−3)+(0×−4)=0

The basic steps are: