Efficient Circuits for Permuting and Mapping Packed Values Across Leveled Homomorphic Ciphertexts

Cloud services are an essential part of our digital infrastructure as organizations outsource large amounts of data storage and computations. While organizations typically keep sensitive data in encrypted form at rest, they decrypt it when performing computations, leaving the cloud provider free to observe the data. Unfortunately, access to...

Lighter is Better: A Lighter Multi-client Verifiable Outsourced Computation with Hybrid Homomorphic Encryption

Gordon et al. (TCC 2015) systematically studied the security of Multi-client Verifiable Computation (MVC), in which a set of computationally-weak clients outsource the computation of a general function f over their private inputs to an untrusted server. They introduced the universally composable (UC) security of MVC and proposed a scheme...

For Your Voice Only: Exploiting Side Channels in Voice Messaging for Environment Detection

Voice messages are an increasingly popular method of communication, accounting for more than 200 million messages a day. Sending audio messages requires a user to invest lesser effort than texting while enhancing the message’s meaning by adding an emotional context (e.g., irony). Unfortunately, we suspect that voice messages might provide...

VAL: Volume and Access Pattern Leakage-Abuse Attack with Leaked Documents

Searchable Encryption schemes provide secure search over encrypted databases while allowing admitted information leakages. Generally, the leakages can be categorized into access and volume pattern. In most existing SE schemes, these leakages are caused by practical designs but are considered an acceptable price to achieve high search...

DEKS: A Secure Cloud-Based Searchable Service Can Make Attackers Pay

Many practical secure systems have been designed to prevent real-world attacks via maximizing the attacking cost so as to reduce attack intentions. Inspired by this philosophy, we propose a new concept named delay encryption with keyword search (DEKS) to resist the notorious keyword guessing attack (KGA), in the context of secure cloud-based...

No-Directional and Backward-Leak Uni-Directional Updatable Encryption Are Equivalent

Updatable encryption (UE) enables the cloud server to update the previously sourced encrypted data to a new key with only an update token received from the client. Two interesting works have been proposed to clarify the relationships among various UE security notions. Jiang (ASIACRYPT 2020) proved the equivalence of every security notion in...