NEC's Augmented Zero-Knowledge Patent: Proving Something About a Set You Can't See

Zero-knowledge proofs prove statements without revealing why they are true. Private membership tests answer a narrower question: is this element in that set? Each is useful alone, but many real problems need both at once — proving, privately, that a hidden value is or is not a member of some set. Is this credential on the revocation list? Is this user not on the sanctions list? Without revealing the value or scanning the list in the open.

US12395341B2, “Augmented zero-knowledge proof with private membership test,” granted to NEC Corporation on August 19, 2025, fuses the two. Classified under H04L 9/3218 (zero-knowledge protocols) with H04L 9/0618 and H04L 9/0656, it claims a proof augmented with a membership test that stays private.

The word “augmented” is the substance. A plain zero-knowledge proof attests to a statement; augmenting it with a private membership test lets the same proof also establish a relationship between a secret value and a set — without leaking the value, and without the verifier having to learn or hold the set in a way that breaks its privacy. Composing primitives cleanly, so the combination still proves what you want and leaks nothing extra, is genuinely hard, which is why it is worth a claim.

The applications are concrete and current. Privacy-preserving compliance — proving you are not on a blocklist — anonymous credentials with revocation, and private set intersection all want this exact shape: a verifiable statement about membership that reveals neither the member nor more of the set than intended. The inventor team includes Karame and Marson, names tied to applied cryptography research, which supports reading this as a real composition rather than a buzzword stack.

Per the desk's discipline: issued grant (B2), not an application; a protocol-method claim, not a deployed product. The composition of two well-studied primitives is the contribution.

For the reader following the zero-knowledge frontier, the 2025 grants increasingly read like this — not new proof systems from scratch, but careful compositions of zero-knowledge with membership tests, query verification, and set operations. That compositional phase is how a cryptographic primitive becomes a toolkit: once the pieces are sound, the value moves to combining them correctly for real problems.