{"document_id":"BLC-STUDY-0110","slug":"semaphore","title":"Semaphore: Zero-Knowledge Signaling on Ethereum","authors":"Kobi Gurkan, Koh Wei Jie and Barry Whitehat","year":2020,"date_label":"2020","publisher":"Kobi Gurkan, Koh Wei Jie and Barry Whitehat","paper_type":"Design paper","category":"Privacy","topics":["Privacy"],"source_url":"https://semaphore.pse.dev/whitepaper-v1.pdf","source_label":"Semaphore proposal, 2020","legacy_pdf_path":null,"sha256":null,"sha256_note":"No hash is published. This build does not store those PDF bytes, so a checksum would be invented. Where a legacy path exists, it points at the Internet Archive copy of the old library.","version":"Source cited by the 2020 study. The study is the reading. This page does not add a second essay.","doi":null,"rights_status":"Official external source only","source_status":"Official source","use_status":"Metadata and commentary only. The reading is the study page.","licence":null,"licence_label":"No licence recorded. Rights status under review.","full_text":null,"full_text_reason":"Full text is not published on this page. Public availability is not a licence to republish a document. Blockchain Lab has not recorded a licence that permits an HTML transcription, a training set, or a retrieval corpus of the paper. Text on this page is Blockchain Lab's own wording, or a pointer to a study that is also Blockchain Lab's wording.","editorial_line":"A member of a group proves they are some member, and posts a signal, without showing which member. A nullifier stops the same member signalling twice in the same context. The 2020 proposal is a base layer for voting and similar uses. It is not itself a mixer, and later versions changed the circuits.","canonical_url":"https://blockchainlab.com/whitepaper/semaphore","record_url":"https://blockchainlab.com/research/corpus/papers/semaphore","study_url":"https://blockchainlab.com/whitepaper/semaphore","last_reviewed":"2026-10-01","last_checked":"2026-10-01","relationships":[{"rel":"Canonical reading","label":"Semaphore study","href":"/whitepaper/semaphore"},{"rel":"Related paper","label":"Zerocoin","href":"/whitepaper/zerocoin"},{"rel":"Related paper","label":"Groth16","href":"/whitepaper/groth16"},{"rel":"Related paper","label":"Zexe","href":"/whitepaper/zexe"}]}