eprint.iacr.orgpaperOff-Key: Inconsistent MAC Keys Compromise Privacy in SPDZ-Family MPC
Off-Key is a privacy attack on SPDZ-family maliciously secure MPC protocols that exploits inconsistent MAC keys. Depending on the MAC check protocol, a corrupted party recovers a shared secret from one authentication check or tests guesses through selective failure. The authors show it in MP-SPDZ, SCALE-MAMBA and FANNG-MPC, where a corrupted party can use different keys across batches, threads or runs, and describe the preprocessing state that enforces key consistency.
TL;DR Shows implementations of SPDZ-family MPC that allow differing MAC keys let a corrupted party leak secrets or test guesses, and how to prevent it.
Organisations named here
- MAC key inconsistency
- Off-Key
- selective failure
- SPDZ
Technologies named here
- SCALE-MAMBA
- FANNG-MPC
- MP-SPDZ
Techniques named here
- Selective failure guess testing
Related in other
eprint.iacr.orgpaperRerandomizable Garbling for Arithmetic Circuits
aseemshrey.inarticle