BLS12-381 syscalls (SIMD-0388) activate at epoch 413 (FG 07)

SIMD-0388 activated at the start of epoch 413 (slot 86,662,112, 18:48 UTC on 17 October). X1 programs now have native support for the BLS12-381 curve: group operations, point checks, decompression and pairings.

What it is

BLS12-381 is a pairing-friendly curve with 128-bit security, a step up from BN254. It is the standard curve for BLS signatures and is used by Ethereum's consensus, Zcash and Filecoin; Ethereum added precompiles for it in 2025. Until now X1 programs could only use BN254 for this kind of cryptography.

Why it's good for X1

• Signatures that combine: BLS lets thousands of signatures merge into one that is checked in a single step. Large signer sets, such as multisigs, oracle networks and committees, become cheap to verify on chain.
• Bridges that check for themselves: Ethereum's sync committee signs block headers with BLS12-381, so an X1 program can verify those headers directly. That is the building block of a light-client bridge that does not depend on a guardian set.
• Stronger zk proofs: systems built on BLS12-381 can now be verified on X1.
• Future consensus work: on Solana this curve underpins the Alpenglow consensus upgrade, where validators register BLS keys with a proof of possession. X1 has not announced Alpenglow, but the groundwork is now in place.

Together with the two BN254 gates before it, this gives X1 the full toolkit for zero-knowledge and signature cryptography that Solana programs have, so that code carries over.

What to watch

It only adds functionality. Existing programs are unaffected and validators on v4.0.3 have nothing to do.

Sources

• The X1 Labs announcement (below)
• SIMD-0388: https://github.com/solana-foundation/solana-improvement-documents/blob/main/proposals/0388-bls12-381-syscalls.md
• Feature account 6omPdxUbzYBosMxYKa9dNUjLxdRkCi3MvHto3NhVcacW, activation slot read from mainnet