Hey guys, I want to present you my vision of generic signature dispatch, enhanced with BCA’s proposal to support hybrid signatures.
This proposal lets the Bitcoin Cash check-signature opcodes verify signatures from more than one scheme, and uses that to add post-quantum (PQ) and hybrid signatures to the VM. A public key’s first byte selects its scheme from a registry: secp256k1 today, with PQ schemes (Falcon-512, SPHINCS+) and others added over time. A compound key binds two schemes under one signer with AND semantics, so a hybrid spend such as secp256k1 + Falcon is valid only if every leg verifies.
No new opcode or output type is added. PQ and hybrid keys spend from ordinary p2pkh outputs committing to HASH160(public-key element), so they work with existing address tooling and keep Double-Spend Proof (DSP) coverage that a script-vault PQ scheme would have to re-earn with extra protocol work.
Which scheme(s) to enable is secondary to the dispatch mechanism. And should be discussed in a follow up topic. However, we want to propose to start with SPHINCS+ (being hash-based) and the hybrid variant, while we await some clarity on lattice schemes.
See full text https://gitlab.com/mainnet-pat/chip-2026-06-generic-sigs