Bug: Some invalid signatures cause .verify to throw instead of returning false

[voltrevo]

This PR adds a failing test showing an example of the bug.

➜  hubble-bls git:(invalid-sig-bug) ✗ npm test

> @thehubbleproject/[email protected] test
> mocha -r ts-node/register test/**/*.test.ts



  Hash to Field
    ✓ expand message
    ✓ hash to point

  BLS raw API
    ✓ parse g1
    ✓ parse g2
    ✓ load and dumps Fr
    ✓ load and dumps G1
    ✓ load and dumps G2
    ✓ verify single signature
    ✓ verify aggregated signature

  BLS Signer
    ✓ verify single signature (78ms)
    ✓ verify aggregated signature (84ms)
    1) rejects invalid signature


  11 passing (396ms)
  1 failing

  1) BLS Signer
       rejects invalid signature:
     Error: err _wrapInput 1 0x059647ae964ea7a386767ab1e41aa47652265bf031ab9d05b70bf5ad1a770a3c 0x0d46b38b1f72d7df1f88786272f0b3fea1c79e1c8515a165fe19939e031ced9e
      at /Users/andrew/workspaces/ethf/hubble-bls/node_modules/mcl-wasm/src/mcl.js:145:22
      at exports.G1._setter (node_modules/mcl-wasm/src/mcl.js:274:19)
      at exports.G1.setStr (node_modules/mcl-wasm/src/mcl.js:484:14)
      at Object.parseG1 (src/mcl.ts:219:8)
      at BlsVerifier.verify (src/signer.ts:59:29)
      at Context.<anonymous> (test/signer.test.ts:68:33)
      at processImmediate (node:internal/timers:464:21)

[ChihChengLiang]

Sorry, haven't got the bandwidth to investigate this.

[jacque006]

@voltrevo mcl-wasm will throw the err _wrapInput with malformed hex values, or values that are out of the supported range. See:

• Format for deserializeHexStr herumi/mcl-wasm#3 (comment)
• Intermittent issue with GT.setStr() herumi/mcl-wasm#8 (comment)

I ran into this same issue and used an openssl generated hex to resolve, see https://github.com/jzaki/bls-wallet/pull/92/files#r787376021 . I am unfortunately not cryptographically experienced enough to provide a more robust explanation.

Two ways I can think of that we can address:

• Add more validation logic to values passed into this lib to throw more meaningful errors.
• Add validation logic in consuming code (such as in bls-wallet-clients) to handle it a layer up.

Thoughts?

[voltrevo]

Sorry, haven't got the bandwidth to investigate this.

👍😞