PVC Implementation

Groth16 proving flows for ID-related circuits, with proof posting to XRPL and on-chain verification.

Circuits

• Allowed: age ≥ 16 check from DOB.
• VerifySign: ECDSA P‑256 signature verification (6×43-bit limb encoding).
• Freshness: nonce + expiration freshness check.
• Full: composite of Allowed + VerifySign + Freshness.

Benchmarks

Module	# Constraints	# Wires	Prover runtime (s)	Proof JSON size (bytes)	Max RSS (MB)
Allowed	121	124	4.82	806	63.75
Freshness	74	75	4.37	803	61.98c
VerifySign	2,205,407	2,190,922	115.89	803	57.25
Full	2,205,606	2,191,121	113.21	806	60.88

Prerequisites

• Circom, SnarkJS, circomlib.
• circom-ecdsa-p256 cloned in the repo root (with its circom-pairing submodule installed).
• Python 3; xrpl-py (see requirements.txt). For key-based signing in VerifySign/Full, install cryptography.

Setup (env + deps)

git submodule update --init --recursive
pip3 install -r requirements.txt

# Create node_modules symlink for circomlib (required for circom-ecdsa-p256)
mkdir -p node_modules
ln -sf ../circomlib node_modules/circomlib

cd circom-ecdsa-p256/circuits
yarn

Build (compile + Groth16 setup)

Use build_setup_multi.py to compile a circuit and produce setup/<Circuit>/ artifacts:

python3 build_setup_multi.py -c Allowed
python3 build_setup_multi.py -c VerifySign
python3 build_setup_multi.py -c Freshness
python3 build_setup_multi.py -c Full

Artifacts: <Circuit>_js/<Circuit>.wasm, <Circuit>_final.zkey, <Circuit>_verification_key.json under setup/<Circuit>/.

Proving and posting to XRPL

prover.py builds the witness, proves with Groth16, compresses proof/public, and posts them as XRPL memos.

Common inputs:

• --raw-id: raw ID JSON (for Allowed and Full).
• --vs-json: optional prebuilt VerifySign witness JSON. If omitted, --vs-priv/--vs-pub + --raw-id are used to sign and build VerifySign witness.
• --fresh-json: freshness input JSON (expectedNonce/nonce/holderTimestamp/validUntil).
• Paths (--wasm/--zkey/--winput/--wtns/--proof/--public) default to setup/<Circuit>/....
• --label: memo label (default Groth16-Proof).

Example:

python3 prover.py -c AllowedOnly
python3 prover.py -c VerifySignOnly

# For Freshness, use a future timestamp for validUntil (e.g., current time + 24 hours)
# Calculate timestamp: python3 -c "import time; print(int(time.time()) + 86400)"
python3 prover.py -c FreshnessOnly --fresh-nonce 123456789 --fresh-valid-until $(python3 -c "import time; print(int(time.time()) + 86400)")
python3 prover.py -c Full --fresh-nonce 123456789 --fresh-valid-until $(python3 -c "import time; print(int(time.time()) + 86400)")

Verifying from XRPL

verifier.py fetches memos by tx hash, reconstructs proof/public, and runs snarkjs groth16 verify.

python3 verifier.py --module Allowed <tx_hash>
python3 verifier.py --module VerifySign <tx_hash>
python3 verifier.py --module Freshness <tx_hash>
python3 verifier.py --module Full <tx_hash>

Key helper

util/make_dummy_id_and_signature.py generates a fresh P‑256 keypair (private.pem, public.pem) under test_inputs/dummy_id1/.