feat(group): make Oprf.Group pluggable

bench/group.bench.ts

@@ -4,7 +4,7 @@
 // at https://opensource.org/licenses/BSD-3-Clause
 
 import Benchmark from 'benchmark'
-import { Group } from '../src/index.js'
+import { Oprf } from '../src/index.js'
 
 function asyncFn(call: CallableFunction) {
     return {
@@ -21,8 +21,8 @@ export async function benchGroup(bs: Benchmark.Suite) {
     const msg = te.encode('msg')
     const dst = te.encode('dst')
 
-    for (const id of Object.values(Group.ID)) {
-        const gg = new Group(id)
+    for (const id of Object.values(Oprf.Group.ID)) {
+        const gg = new Oprf.Group(id)
         const k = await gg.randomScalar()
         const P = gg.mulGen(k)
         const Q = P.mul(k)

package.json

@@ -40,7 +40,8 @@
         "eslint-plugin-security": "1.5.0",
         "jest": "29.3.1",
         "prettier": "2.7.1",
-        "typescript": "4.8.4"
+        "typescript": "4.8.4",
+        "sjcl": "1.0.8"
     },
     "scripts": {
         "prepack": "tsc -b",
@@ -52,8 +53,5 @@
         "lint": "eslint .",
         "bench": "tsc -b bench && node ./lib/bench/index.js",
         "format": "prettier './(src|test|bench|examples)/*.ts' --write"
-    },
-    "dependencies": {
-        "sjcl": "1.0.8"
     }
 }

src/client.ts

@@ -3,7 +3,7 @@
 // Licensed under the BSD-3-Clause license found in the LICENSE file or
 // at https://opensource.org/licenses/BSD-3-Clause
 
-import { Elt, Scalar } from './group.js'
+import { Elt, Scalar } from './groupTypes.js'
 import { Evaluation, EvaluationRequest, FinalizeData, ModeID, Oprf, SuiteID } from './oprf.js'
 
 import { zip } from './util.js'
@@ -76,7 +76,7 @@ export class VOPRFClient extends baseClient {
         if (!evaluation.proof) {
             throw new Error('no proof provided')
         }
-        const pkS = Elt.deserialize(this.gg, this.pubKeyServer)
+        const pkS = this.gg.desElt(this.pubKeyServer)
 
         const n = finData.inputs.length
         if (evaluation.evaluated.length !== n) {
@@ -104,7 +104,7 @@ export class POPRFClient extends baseClient {
     private async pointFromInfo(info: Uint8Array): Promise<Elt> {
         const m = await this.scalarFromInfo(info)
         const T = this.gg.mulGen(m)
-        const pkS = Elt.deserialize(this.gg, this.pubKeyServer)
+        const pkS = this.gg.desElt(this.pubKeyServer)
         const tw = pkS.add(T)
         if (tw.isIdentity()) {
             throw new Error('invalid info')

src/dleq.ts

@@ -5,7 +5,7 @@
 //
 // Implementation of batched discrete log equivalents proofs (DLEQ) as
 // described in https://www.ietf.org/id/draft-irtf-cfrg-voprf-09.html#name-discrete-log-equivalence-pr.
-import { Elt, Group, Scalar } from './group.js'
+import { Elt, Group, Scalar } from './groupTypes.js'
 import { checkSize, joinAll, to16bits, toU16LenPrefix } from './util.js'
 
 export interface DLEQParams {
@@ -121,14 +121,15 @@ export class DLEQProof {
     }
 
     static size(params: DLEQParams): number {
-        return 2 * Scalar.size(params.gg)
+        return 2 * params.gg.scalarSize()
     }
 
     static deserialize(params: Required<DLEQParams>, bytes: Uint8Array): DLEQProof {
         checkSize(bytes, DLEQProof, params)
-        const n = Scalar.size(params.gg)
-        const c = Scalar.deserialize(params.gg, bytes.subarray(0, n))
-        const s = Scalar.deserialize(params.gg, bytes.subarray(n, 2 * n))
+        const group = params.gg
+        const n = group.scalarSize()
+        const c = group.desScalar(bytes.subarray(0, n))
+        const s = group.desScalar(bytes.subarray(n, 2 * n))
         return new DLEQProof(params, c, s)
     }
 }