keyring->pair->vrfVerify: possibly the wrong public key is used if the pair type is sr25519

[farwayer]

• I'm submitting a bug

  • [x] Bug report

• What is the current behavior and expected behavior?

Vrf signature should be checked agains remote public key (passed as signerPublic parameter). But if the pair type is sr25519 then the current pair publicKey is possibly misused for validation.

https://github.com/polkadot-js/common/blob/6971012f4af62f453ba25d83d0ebbfd12eaf5709/packages/keyring/src/pair/index.ts#L211

• Please tell us about your environment:

  • Version: 12.6.2

  • Environment:

  • [x] Node.js

  • [x] Browser

  • [x] Other (limited support for other environments)

  • Language:

  • [x] JavaScript

  • [x] TypeScript (include tsc --version)

[farwayer]

Since the verification uses a remote public key, it makes sense to make vrfVerify a utility-function rather than making it a pair method.