Searching Keywords with Wildcards on Encrypted Data


Sedghi, S. and Liesdonk, Peter van and Nikova, Svetla and Hartel, Pieter and Jonker, Willem (2010) Searching Keywords with Wildcards on Encrypted Data. [Report]

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Abstract:A hidden vector encryption scheme (HVE) is a derivation of identity-based encryption, where the public key is actually a vector over a certain alphabet.
The decryption key is also derived from such a vector, but this one is also allowed to have ``$\star$'' (or wildcard) entries. Decryption is possible as long as these tuples agree on every position except where a ``$\star$''

These schemes are useful for a variety of applications: they can be used as building block to construct attribute-based encryption schemes and sophisticated predicate encryption schemes (for e.g. range or subset queries).
Another interesting application -- and our main motivation -- is to create searchable encryption schemes that support queries for keywords containing wildcards.

Here we construct a new HVE scheme, based on bilinear groups of prime order, which supports vectors over any alphabet.
The resulting ciphertext length is equally shorter than existing schemes, depending on a trade-off. The length of the decryption key and the computational complexity of decryption are both constant, unlike existing schemes where these are both dependent on the amount of non-wildcard symbols associated to the decryption key.

Our construction hides both the plaintext and public key used for encryption.
We prove security in a selective model, under the decision linear assumption.

Item Type:Report
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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