This was part of #558 (for 20 months) to demonstrate the advantages of batch verification (see graph), but then removed to simplify #558 because there are still ongoing discussions:
- there’s @real-or-random’s proposal to add synthetic randomness for batch verification (https://github.com/sipa/bips/issues/204)
- batch verification fairly well tested, but still wouldn’t be comfortable with using this in Bitcoin Core for consensus in its current state because it relies on parts of the lib that are otherwise unused such as scratch spaces and ecmult_multi. Ideally we would have comprehensive fuzz tests for batch verification.
- adding chacha20 may not be worth it, because it may only provide a negligible speedup over SHA256 (TODO: test this), plus we’re planning to allow overriding the SHA256 implementation at compile time (https://github.com/bitcoin-core/secp256k1/pull/558#issuecomment-619579991).