REPUTRANS

Prove things about yourself without revealing the underlying data.

A university signs your degree. You want to prove you studied Computer Science - but not reveal your name, GPA, or graduation year. REPUTRANS lets you do exactly that: generate a cryptographic proof that discloses only the fields you choose, and a verifier can check it without ever seeing the original credential.

You can also prove things about hidden values. "My GPA is at least 3.0" - the verifier sees that the statement is true, but never learns the actual number.

Two proof types:

• Selective disclosure - reveal specific fields, hide the rest
• Range proofs - prove a numeric field meets a threshold (>= or <=) without revealing the value

Everything runs locally on your machine. No blockchain, no server, no accounts. Real cryptography built on Noir zero-knowledge circuits with Barretenberg UltraHonk proofs.

Quick Start

Prerequisites: Node.js 18+

npx reputrans keygen
npx reputrans issue
npx reputrans inspect
npx reputrans prove --disclose field_of_study
npx reputrans verify

Five commands, zero config. Each command auto-detects output files from the previous step, so you don't need to pass file paths.

| Command | What it does | |---|---| | keygen | Generate an issuer keypair (e.g. a university or employer) | | issue | Sign claims into a verifiable credential. Without --claims, uses an example | | inspect | Show credential fields and what proof types each supports | | prove | Generate a zero-knowledge proof (see syntax below) | | verify | Check a proof mathematically - no trust, no credential needed |

Prove syntax

The prove command supports two flags:

--disclose - reveal specific fields, hide the rest:

npx reputrans prove --disclose field_of_study
# Verifier sees: field_of_study = "Computer Science"
# Verifier does NOT see: name, gpa, graduation_year

--range - prove a numeric value meets a threshold without revealing it:

npx reputrans prove --range gpa:gte:3.0
# Verifier sees: gpa >= 3.0 (TRUE)
# Verifier does NOT see: the actual GPA value

Range format is field:operator:threshold where:

• gte = greater than or equal to (>=)
• lte = less than or equal to (<=)

Combine both in a single proof:

npx reputrans prove --disclose department --range clearance:gte:2
# Verifier sees: department = "R&D", clearance >= 2
# Verifier does NOT see: the actual clearance level, role, or any other fields

Custom Credentials

Create a claims.json with any fields you want:

{
  "role": "engineer",
  "clearance": "3",
  "department": "R&D",
  "years_experience": "7"
}

Then:

npx reputrans keygen --name "Acme Corp"
npx reputrans issue --key acme-corp-key.json --claims claims.json
npx reputrans inspect
npx reputrans prove --disclose department --range clearance:gte:2
npx reputrans verify

Numeric fields (like clearance and years_experience) automatically support range proofs. String fields support selective disclosure.

Install Globally (optional)

npm install -g reputrans
reputrans keygen

How It Works

REPUTRANS uses three roles:

1. Issuer - generates a keypair and signs claims into a credential. The credential is a Poseidon Merkle tree of field hashes, signed with an EdDSA signature over BabyJubjub
2. Provar (credential holder) - generates a ZK proof revealing only selected fields. The proof is computed inside a Noir circuit that verifies the issuer's signature, validates Merkle paths for disclosed fields, and checks range constraints - all in zero knowledge
3. Arbiter (verifier) - checks the proof. This is pure math - no trust required, no contact with the issuer, no access to the original credential

The proof is portable. Verify it on any machine, via the included REST API, or on-chain. No blockchain required for the basic flow.

Architecture

reputrans/
  circuits/     7 Noir circuits (compiled to Barretenberg UltraHonk)
  sdk/src/      TypeScript SDK (poseidon, eddsa, encoder, identity, prover, verifier)
  cli/src/      CLI commands (keygen, issue, inspect, prove, verify)
  verifier/     REST verifier service with DID resolution

Circuits

| Circuit | Purpose | Used by CLI | |---|---|---| | composite | EdDSA signature verify + Merkle selective disclosure + range proof | Yes - the main circuit | | field_disclosure | Standalone selective disclosure | No | | range_proof | Standalone range check | No | | set_membership | Merkle tree membership proof | No | | signature_verify | Standalone EdDSA verification | No | | poseidon_compat | Cross-boundary hash validation | Testing only | | map_to_curve | BabyJubjub point mapping | Optimization, not required |

The CLI uses the composite circuit for everything. The standalone circuits exist for modularity and testing.

CLI Reference

| Command | Required args | Optional args | Auto-detects | |---|---|---|---| | keygen | none | --name, --out | - | | issue | none | --key, --claims, --out | *-key.json | | inspect | none | --credential | credential-*.json | | prove | --disclose or --range | --credential, --out | credential-*.json | | verify | none | --proof | proof-*.json |

Range format: field:operator:threshold

• gte = greater than or equal to (>=)
• lte = less than or equal to (<=)
• Examples: gpa:gte:3 (GPA is at least 3), age:lte:65 (age is at most 65)

Development

git clone https://github.com/danielabrahamx/reputrans-core.git
cd reputrans-core
npm install
npm run build
npm test         # 91 tests, including real ZK proof generation
npm run test:e2e # full CLI lifecycle test

Protocol Roles

• Provar - the credential holder who generates proofs
• Arbiter - the verifier who checks proofs

Anyone can be an issuer. The Provar does not need their own keys - the credential file contains everything needed for proof generation. Anonymous identity (master secret, nullifiers) is available in the Enterprise product.

License

MIT