vacp2p/semaphore-rs
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Merge pull request #1 from worldcoin/philsippl/extract_external_nullifier

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extract external_nullifier calculation
This commit is contained in:
Remco Bloemen 2022-03-10 13:23:00 -08:00 committed by GitHub
commit 9b8988419d
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3 changed files with 24 additions and 16 deletions
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13
README.md
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@ -32,21 +32,22 @@ let (_, leaf) = id.commitment().to_bytes_be();
tree.set(0, leaf.into());
let merkle_proof = tree.proof(0).expect("proof should exist");
let root = tree.root().into();
let root = tree.root();
// change signal and external_nullifier here
let signal = "hello".as_bytes();
let external_nullifier = "123".as_bytes();
let signal = "xxx".as_bytes();
let external_nullifier = "appId".as_bytes();
let nullifier_hash = generate_nullifier_hash(&id, external_nullifier);
let external_nullifier_hash = hash_external_nullifier(external_nullifier);
let nullifier_hash = generate_nullifier_hash(&id, &external_nullifier_hash);
let config = SnarkFileConfig {
zkey: "./semaphore/build/snark/semaphore_final.zkey".to_string(),
wasm: "./semaphore/build/snark/semaphore.wasm".to_string(),
};
let proof = generate_proof(&config, &id, &merkle_proof, external_nullifier, signal).unwrap();
let success = verify_proof(&config, &root, &nullifier_hash, signal, external_nullifier, &proof).unwrap();
let proof = generate_proof(&config, &id, &merkle_proof, &external_nullifier_hash, signal).unwrap();
let success = verify_proof(&config, &root.into(), &nullifier_hash, signal, &external_nullifier_hash, &proof).unwrap();
assert!(success);
```

7
src/lib.rs
View File

@ -43,7 +43,8 @@ mod test {
let signal = "xxx".as_bytes();
let external_nullifier = "appId".as_bytes();
let nullifier_hash = generate_nullifier_hash(&id, external_nullifier);
let external_nullifier_hash = hash_external_nullifier(external_nullifier);
let nullifier_hash = generate_nullifier_hash(&id, &external_nullifier_hash);
let config = SnarkFileConfig {
zkey: "./semaphore/build/snark/semaphore_final.zkey".to_string(),
@ -51,14 +52,14 @@ mod test {
};
let proof =
generate_proof(&config, &id, &merkle_proof, external_nullifier, signal).unwrap();
generate_proof(&config, &id, &merkle_proof, &external_nullifier_hash, signal).unwrap();
let success = verify_proof(
&config,
&root.into(),
&nullifier_hash,
signal,
external_nullifier,
&external_nullifier_hash,
&proof,
)
.unwrap();

20
src/protocol.rs
View File

@ -45,17 +45,23 @@ fn hash_signal(signal: &[u8]) -> BigInt {
}
/// Internal helper to hash the external nullifier
pub fn hash_external_nullifier(nullifier: &[u8]) -> BigInt {
let mut hash = keccak256(nullifier).to_vec();
hash.splice(..3, vec![0; 4]);
BigInt::from_bytes_be(Sign::Plus, &hash)
pub fn hash_external_nullifier(nullifier: &[u8]) -> [u8; 32] {
let mut hash = keccak256(nullifier);
hash[0] = 0;
hash[1] = 0;
hash[2] = 0;
hash[3] = 0;
hash
}
/// Generates the nullifier hash
pub fn generate_nullifier_hash(identity: &Identity, external_nullifier: &[u8]) -> BigInt {
let res = POSEIDON
.hash(vec![
bigint_to_fr(&hash_external_nullifier(external_nullifier)),
bigint_to_fr(&BigInt::from_bytes_be(
Sign::Plus,
external_nullifier,
)),
bigint_to_fr(&identity.nullifier),
])
.unwrap();
@ -90,7 +96,7 @@ pub fn generate_proof(
merkle_proof_to_vec(merkle_proof),
);
inputs.insert("externalNullifier".to_string(), vec![
hash_external_nullifier(external_nullifier),
BigInt::from_bytes_be(Sign::Plus, external_nullifier),
]);
inputs.insert("signalHash".to_string(), vec![hash_signal(signal)]);
@ -151,7 +157,7 @@ pub fn verify_proof(
Fp256::from(nullifier_hash.to_biguint().unwrap()),
Fp256::from(hash_signal(signal).to_biguint().unwrap()),
Fp256::from(
hash_external_nullifier(external_nullifier)
BigInt::from_bytes_be(Sign::Plus, external_nullifier)
.to_biguint()
.unwrap(),
),