diff --git a/src/functional.ts b/src/functional.ts index aac05ca..e59d0b4 100644 --- a/src/functional.ts +++ b/src/functional.ts @@ -108,8 +108,12 @@ export function functionalInterfaceFactory({ /** * Verifies multiple signatures at once returning true if all valid or false - * if at least one is not. Optimized method when knowing which signature is - * wrong is not relevant, i.e. verifying an Eth2.0 block. + * if at least one is not. Optimization useful when knowing which signature is + * wrong is not relevant, i.e. verifying an entire Eth2.0 block. + * + * This method provides a safe way to do so by multiplying each signature by + * a random number so an attacker cannot craft a malicious signature that won't + * verify on its own but will if it's added to a specific predictable signature * https://ethresear.ch/t/fast-verification-of-multiple-bls-signatures/5407 */ function verifyMultipleSignatures( diff --git a/test/unit/index.test.ts b/test/unit/index.test.ts index cf50d4a..627919f 100644 --- a/test/unit/index.test.ts +++ b/test/unit/index.test.ts @@ -1,6 +1,7 @@ import {expect} from "chai"; import {IBls} from "../../src/interface"; import {getN, randomMessage} from "../util"; +import {hexToBytes} from "../../src/helpers"; export function runIndexTests(bls: IBls): void { // eslint-disable-next-line @typescript-eslint/explicit-function-return-type @@ -90,4 +91,85 @@ export function runIndexTests(bls: IBls): void { expect(isValid).to.be.false; }); }); + + describe("verifyMultipleSignatures", () => { + it("Should verify multiple signatures", () => { + const n = 4; + const dataArr = getN(n, () => { + const sk = bls.SecretKey.fromKeygen(); + const pk = sk.toPublicKey(); + const msg = randomMessage(); + const sig = sk.sign(msg); + return {pk, msg, sig}; + }); + const pks = dataArr.map((data) => data.pk); + const msgs = dataArr.map((data) => data.msg); + const sigs = dataArr.map((data) => data.sig); + + expect( + bls.verifyMultipleSignatures( + pks.map((pk) => pk.toBytes()), + msgs, + sigs.map((sig) => sig.toBytes()) + ) + ).to.equal(true, "functional (bytes serialized) interface failed"); + + expect(bls.Signature.verifyMultipleSignatures(pks, msgs, sigs)).to.equal(true, "class interface failed"); + }); + + it("Test fails correctly against a malicous signature", async () => { + // Data computed with lower level BLS primitives + // https://github.com/dapplion/eth2-bls-wasm/blob/2d2f3e6a0487e96706bfd8a1b8039c7d6c79f71f/verifyMultipleSignatures.test.js#L40 + // It creates N valid signatures + // It messes with the last 2 signatures, modifying their values + // such that they wqould not fail in aggregate signature verification. + // Creates a random G2 point with is added to the last signature + // and substracted to the second to last signature + const maliciousSignatureTestData = { + pks: [ + "b836ccf44fa01e46745ccc3a47855e959783ef5df5cdcc607354b98d52c16b6613761339bfb833fd525cdca7c8071c6b", + "a317ce36dcf2bf6fd262dbad80427f890bc166152682cb6c600a66eb7d525f200839ab798ca4877c3143a31201905de4", + "b9b7b4f4a88d98f34b4c9ba8ae10e935ba51164ddc045d6ae26b403c87a6934e6c75f9fb5cc4b3b29a1255b316d08de5", + "a386a2bc7e9d13cf9b4ad3c819547534c768aeae6a2414bfcebee50f38aaf85a9d610974db931278c08fe86a91eb2999", + ], + msgs: [ + "690a91fc0a7a49bbc5afe9516c1831ca8845f281ef2e414f7dfeb71b5e91a902", + "3829d4fc2332afc2634079823b89598f3674be5da324b1092b3d8aeb7af5e164", + "9a9406647ed6af16b5ce3e828c5f5ef35f1221ed10476209476c12776ce417ac", + "3e8e4bcb78fda59a43ebfb90970cc6036ce18dc3d3a1b714cc4c1bfc00b8258e", + ], + sigs: [ + "864ed65f224cf4e49e9bbf313d3dc243649885d9bd432a15e6c1259f2e4c29fcefa7a4c3aafaac01519f7c92239702d7096df2971b1801cd26d0ca0d5e7743ccb0abe79d8c383f9bb04ebe553a3094e84d55bc79be7eff5ffdb9b322205acfd1", + "90efd8c82c356956fc170bec2aed874d14cea079625dfe69d8bc375e10fcd96e2c0348dfeb713f1889629ccb9ec95fee0e0c9cc7a728d8a7068701a04192ed585ec761edf6e2c1e44ceaaa61732052af81a6033fa7d375d7f7157909549322da", + "9023f43cc8e05a3e842b242b9f6781a9e2eadbfcbebd1242563e56bb47cd273ef20fc0c5099e05e83093581907bfd02915b5ef8c553918d4524c274a8856950c87c6314a2c003a2ed28e5fb56ddfdb233a2b895c2397bd15629325d95ca43b83", + "82c8fedc6ad43e945bbf7529d55b73d7ce593bc9ea94dfaf91d720b2ab0e51ce551f7fcda96d428b627ff776c94d6f360af425fe7fb4e4469b893071149db747f27a8bd488af7ba7f0edf86c7e551af89d7a55d4fc86968e10f91ed76e68e373", + ], + manipulated: [false, false, true, true], + }; + + const pks = maliciousSignatureTestData.pks.map(hexToBytes); + const msgs = maliciousSignatureTestData.msgs.map(hexToBytes); + const sigs = maliciousSignatureTestData.sigs.map(hexToBytes); + + maliciousSignatureTestData.manipulated.forEach((isManipulated, i) => { + expect(bls.verify(pks[i], msgs[i], sigs[i])).to.equal( + !isManipulated, + isManipulated ? "Manipulated signature should not verify" : "Ok signature should verify" + ); + }); + + // This method (AggregateVerify in BLS spec lingo) should verify + const dangerousAggSig = bls.aggregateSignatures(sigs); + expect(bls.verifyMultiple(pks, msgs, dangerousAggSig)).to.equal( + true, + "Malicious signature should be validated with bls.verifyMultiple" + ); + + // This method is expected to catch the malicious signature and not verify + expect(bls.verifyMultipleSignatures(pks, msgs, sigs)).to.equal( + false, + "Malicous signature should not validate with bls.verifyMultipleSignatures" + ); + }); + }); }