ZKP Syscall (alt_bn128)

The alt_bn128 syscalls are native BPF VM system calls added to the Solana runtime (via SIMD-0041 and related proposals) that expose elliptic curve operations on the BN254 curve (also known as alt_bn128) — specifically point addition, scalar multiplication, and pairing checks — enabling on-chain programs to verify Groth16 zk-SNARK proofs within practical compute unit budgets. Without these syscalls, implementing the pairing-based verification of a Groth16 proof purely in BPF bytecode would require hundreds of millions of compute units, far exceeding the 1.4M per-transaction limit; with the syscalls, a full Groth16 verification costs on the order of 200,000–400,000 compute units. Light Protocol's on-chain verifier and Solana's Token-2022 Confidential Transfers both depend on the alt_bn128 syscalls, making them a critical piece of Solana's ZK infrastructure.