BLS12381 scheme lacks subgroup check in v1.13.15

[txhsl]

Rationale

The current Geth version v1.13.15 we are using doesn't perform subgroup check, only expect before bls12381Pairing. Ethereum introduced this fix through ethereum/EIPs#8456, and finally implemented in v1.14.2 through ethereum/go-ethereum#29637.

Implementation

Since we are using Consensys/gnark-crypto for most of the encoding/decoding, the BLS signature and Envelope transaction are well-checked, so that no need to update.

But the EVM format related decoding only checks IsOnCurve(). This happens in decodePointG1() and decodePointG2() of both EVM precompiles and DKG.

I'm going to add BLS12381 subgroup check to our crypto/tpke, but leave the code in core/vm/contracts.go for v1.14.2 upgrade.

[dusmart]

Thank you for the detailed description of the issue! Please keep this issue open until we merge v1.14.2, after which we can close it. I truly appreciate the effort you put into outlining the details.

[txhsl]

Fixed in #495.