Anonymous credentials (AC) offer privacy in user-centric identity management. They enable users to authenticate anonymously, revealing only necessary attributes. With the rise of decentralized systems like self-sovereign identity, the demand for efficient AC systems in a decentralized setting has grown. Relying on conventional AC systems, however, require users to present independent credentials when obtaining them from different issuers, leading to increased complexity. AC systems should ideally support being multi-authority for efficient presentation of multiple credentials from various issuers. Another vital property is issuer hiding, ensuring that the issuer's identity remains concealed, revealing only compliance with the verifier's policy. This prevents unique identification based on the sole combination of credential issuers. To date, there exists no AC scheme satisfying both properties simultaneously.

Efficiently searchable and easily deployable encryption schemes enable an untrusted, legacy service such as a relational database engine to perform searches over encrypted data. The ease with which such schemes can be deployed on top of existing services makes them especially appealing in operational environments where encryption is needed but it is not feasible to replace large infrastructure components like databases or document management systems. Unfortunately all previously known approaches for efficiently searchable and easily deployable encryption are vulnerable to inference attacks where an adversary can use knowledge of the distribution of the data to recover the plaintext with high probability. We present a new efficiently searchable, easily deployable database encryption scheme that is provably secure against inference attacks even when used with real, low-entropy data. We implemented our constructions in Haskell and tested databases up to 10 million records showing our construction properly balances security, deployability and performance.