Grade Claim Proof

Once a user has obtained a credential, their grade commitment is added to the grade group. Similar to a Semaphore inclusion proof, they can signal anonymously with a zero-knowledge proof that proves that:

• they obtained a grade over a certain threshold, and

• the same user created the signal and the proof

Generating a Proof

You can use the @bq-core/lib library to generate such proofs, passing the following parameters to the generateGradeClaimProof function:

• identity: the Semaphore identity of the user generating the proof.

• gradeGroupOrMerkleProof: the grade group to which the user belongs, or the corresponding Merkle proof.

• gradeThreshold: the value the user claims to have a higher grade than.

• externalNullifier: the value that prevents double-signaling.

• signal: the signal the user wants to send anonymously.

• gradeCommitmentOrTestGradingVariables: this variable can either be:

  • The TestGradingVariables, composed of the multipleChoiceWeight and the nQuestions. If this value is provided, the grade the user obtained is brute forced from their identity and grade group by testing all the possible grades they could have obtained.

  • The FullGradeCommitment, composed of the value of the grade commitment (gradeCommitmentValue) as specified for the grade claim circuit, its index within the grade tree (gradeCommitmentIndex), and the grade obtained.

• snarkArtifacts: the zkey and wasm trusted setup files.

Verifying a Proof Off-Chain

You can use the @bq-core/lib library to verify a generated proof via the verifyGradeClaimProof function:

import { verifyGradeClaimProof } from "@bq-core/lib"

await verifyGradeClaimProof(gradeClaimProof) // true or false.

Which returns a promise that resolves to true or false.