semaphore:prove

Prove membership in a Semaphore group anonymously, signaling a message nullified per scope, and bind the proof JSON to . Uses the production ceremony artifacts for the group's tree depth. Requires an identity derived this session (semaphore:identity).

⚗️ Experimental — available at next.evmcrispr.com.

Syntax

semaphore:prove <variable>

Arguments

Name	Type	Description
`variable`	`variable`	Variable to bind the proof JSON to

Options

Name	Type	Description
`--group`	`number`	Group id to prove membership in
`--message`	`any`	Message (number, hex or string) the proof signals
`--scope`	`any`	Scope (external nullifier) — one accepted proof per identity per scope
`--identity`	`number`	Identity commitment to prove with (default: the only identity of this session)

Signals and scopes

--message is the value your proof signals; --scope is the external nullifier — the contract accepts one proof per identity per scope, so scope a poll id, an epoch, or any replay boundary. Values may be numbers, hex, or strings (a string becomes its UTF-8 bytes as a number, matching the Semaphore SDK). Raw values ride in the proof JSON; the circuit sees them keccak-hashed, exactly as the contract re-hashes them on verification.

Artifacts

Proving uses the real Semaphore ceremony artifacts for the group's tree depth, fetched from snark-artifacts.pse.dev on first use and cached for the session. There is no dev-mode setup: these proofs are production-grade.

Examples

load semaphore

# One-time: derive your identity (the wallet signs a fixed message)
semaphore:identity $me

# Group admin
semaphore:create-group $group
semaphore:add-member $me to $group

# Anonymous signal: prove membership, nullified per scope
semaphore:prove $proof --group $group --message "approve proposal 42" --scope 42
semaphore:validate $proof for $group