Add support for evmnet

lib/beacon-verification.ts

@@ -1,5 +1,8 @@
 import { bls12_381 as bls } from '@noble/curves/bls12-381'
+import { bn254 } from '@kevincharm/noble-bn254-drand'
+import type { CHash } from '@noble/curves/abstract/utils'
 import { sha256 } from '@noble/hashes/sha256'
+import { keccak_256 } from '@noble/hashes/sha3'
 import { ensureBytes }  from '@noble/curves/abstract/utils'
 import {Buffer} from 'buffer'
 import {
@@ -11,7 +14,8 @@ import {
     G2UnchainedBeacon,
     isG1G2SwappedBeacon,
     G1UnchainedBeacon,
-    isG1Rfc9380
+    isG1Rfc9380,
+    isBn254OnG1
 } from './index'
 
 type PointG1 = typeof bls.G1.ProjectivePoint.ZERO
@@ -46,6 +50,12 @@ async function verifyBeacon(chainInfo: ChainInfo, beacon: RandomnessBeacon, expe
         return verifySigOnG1(beacon.signature, await unchainedBeaconMessage(beacon), publicKey, 'BLS_SIG_BLS12381G1_XMD:SHA-256_SSWU_RO_NUL_')
     }
 
+    if (isBn254OnG1(beacon, chainInfo)) {
+        return bn254.verifyShortSignature(beacon.signature, await unchainedBeaconMessage(beacon, keccak_256), publicKey, {
+            DST: 'BLS_SIG_BN254G1_XMD:KECCAK-256_SVDW_RO_NUL_'
+        })
+    }
+
     console.error(`Beacon type ${chainInfo.schemeID} was not supported or the beacon was not of the purported type`)
     return false
 
@@ -93,8 +103,8 @@ async function chainedBeaconMessage(beacon: G2ChainedBeacon): Promise<Uint8Array
     return sha256(message)
 }
 
-async function unchainedBeaconMessage(beacon: G2UnchainedBeacon | G1UnchainedBeacon): Promise<Uint8Array> {
-    return sha256(roundBuffer(beacon.round))
+async function unchainedBeaconMessage(beacon: G2UnchainedBeacon | G1UnchainedBeacon, hashFn: CHash = sha256): Promise<Uint8Array> {
+    return hashFn(roundBuffer(beacon.round))
 }
 
 function signatureBuffer(sig: string) {

lib/index.ts

@@ -144,7 +144,7 @@ export type ChainInfo = {
 }
 
 // currently drand supports chained and unchained randomness - read more here: https://drand.love/docs/cryptography/#randomness
-export type RandomnessBeacon = G2ChainedBeacon | G2UnchainedBeacon | G1UnchainedBeacon | G1RFC9380Beacon
+export type RandomnessBeacon = G2ChainedBeacon | G2UnchainedBeacon | G1UnchainedBeacon | G1RFC9380Beacon | Bn254OnG1Beacon
 
 export type G2ChainedBeacon = {
     round: number
@@ -177,6 +177,14 @@ export type G1RFC9380Beacon = {
     _phantomg19380?: never
 }
 
+export type Bn254OnG1Beacon = {
+    round: number
+    randomness: string
+    signature: string
+    // this distinguishes it from the other unchained beacons so the type guard works correctly
+    _phantombn254ong1?: never
+}
+
 // eslint-disable-next-line  @typescript-eslint/no-explicit-any
 export function isChainedBeacon(value: any, info: ChainInfo): value is G2ChainedBeacon {
     return info.schemeID === 'pedersen-bls-chained' &&
@@ -214,6 +222,15 @@ export function isG1Rfc9380(value: any, info: ChainInfo): value is G1RFC9380Beac
         value.round > 0
 }
 
+// eslint-disable-next-line  @typescript-eslint/no-explicit-any
+export function isBn254OnG1(value: any, info: ChainInfo): value is Bn254OnG1Beacon {
+    return info.schemeID === 'bls-bn254-unchained-on-g1' &&
+        !!value.randomness &&
+        !!value.signature &&
+        value.previous_signature === undefined &&
+        value.round > 0
+}
+
 // exports some default implementations of the above interfaces and other utility functions that could be used with them
 export {
     HttpChain,

package.json

@@ -31,7 +31,8 @@
   },
   "dependencies": {
     "@babel/traverse": "^7.23.2",
-    "@noble/curves": "^1.4.0",
+    "@kevincharm/noble-bn254-drand": "^0.0.1",
+    "@noble/curves": "^1.6.0",
     "buffer": "^6.0.3"
   },
   "repository": {

test/beacon-verification.test.ts

@@ -207,4 +207,29 @@ describe('verifyBeacon', () => {
             await expect(verifyBeacon(chainInfo, validBeacon, 2)).resolves.toEqual(false)
         })
     })
+
+    describe('signatures on BN254 G1', () => {
+        // TODO: Replace data with evmnet when it's live
+        const validBeacon = {
+            round: 10,
+            signature:
+                '0fd919ec1490bf01935f348837bd20f49f539c5adfd60ce29648fe16f8dbed8803bf3e8fb4c3cbce5dcb642333d81260a811cc432b2f7a687b9b7c2305ad01ee',
+            randomness: 'a62a0e81920b40fb361f9106efb34199af1fbdb0c53db51f7acbad73e0d9d0bf',
+        }
+
+        const chainInfo = {
+            public_key:
+                '14018a8127d0cd185f0d0cd168bec330c584581d46f77f41e8ee33ad600588e104961f20efbcec8ce5e176aa182bf141f7059cfb467e3b508bc6f36f227d5cf31c7baa2a010677e813ffca24b4ff5faf3348b2750201c85b126a480118b149f514d3e7aba46a99f40aac6507a2c6d6f3c7a6b38038786831e3e6b5b0adf5894b',
+            period: 3,
+            genesis_time: 1726958055,
+            hash: 'f50064cd5f71a2e2de647940ac7fa2fd9f6128129ada163e971625ec9f082db2',
+            groupHash: '3a7cd8aa1864ff0cf8837e1bf77dad871aaaa8f046041ccecce74ab4e029f30c',
+            schemeID: 'bls-bn254-unchained-on-g1',
+            metadata: { beaconID: 'default' },
+        }
+
+        it('should verify a valid signature', async () => {
+            await expect(verifyBeacon(chainInfo, validBeacon, validBeacon.round)).resolves.toEqual(true)
+        })
+    })
 })