Fix a bug about duplicate validator key

[gguoss]

Thank you for your Pull Request!

Before you submitting, please check that:

• You added a brief description of the PR, e.g.:
  • What does it do?
  • What important points reviewers should know?
  • Is there something left for follow-up PRs?
• You labeled the PR with appropriate labels if you have permissions to do so.
• You mentioned a related issue if this PR related to it, e.g. Fixes #228 or Related #1337.
• You asked any particular reviewers to review. If you aren't sure, start with GH suggestions.
• Your PR adheres the style guide
  • In particular, mind the maximal line length.
  • There is no commented code checked in unless necessary.
  • Any panickers have a proof or removed.
• You bumped the runtime version if there are breaking changes in the runtime.
• You updated any rustdocs which may have changed

After you've read this notice feel free to remove it.
Thank you!

✄ -----------------------------------------------------------------------------

[gavofyork]

what bug is this meant to fix?

[gguoss]

what bug is this meant to fix?

Validator (A, B ).

• A: AuthorityKey ( authA )
• B: also set AuthorityKey ( authA), then B can't run a node.

Validator's key will be two same AuthorityKey.

[gavofyork]

please explain further.

[bkchr]

@gguoss ping

[gguoss]

Registering the authority node does not require any physical machine to run the node. Because I just need to set my authority key to the existing authority key of the running node. This way I can get dividends as usual.

[gguoss]

Registering the authority node does not require any physical machine to run the node. Because I just need to set my authority key to the existing authority key of the running node. This way I can get dividends as usual.

The reason for doing evil is: A duplicate authority key can be added to the aura consensus.

[gavofyork]

it should remove the current entry for NextKeyFor(who) in KeyFilterMap.

[gavofyork]

so this is to prevent two validators assigning themselves the same session key?

[gguoss]

so this is to prevent two validators assigning themselves the same session key?

yes

[gavofyork]

This is superseded now.