Protocol / Security boundary
Post-quantum blockchain architecture from genesis
SOS was designed so that every security-bearing primitive on the SOS side of each trust boundary has a post-quantum construction. This is broader than replacing a transaction signature: consensus, private notes, commitments, nullifiers, and proof verification all belong to the same threat model.
Implemented on the public testnet; pre-mainnet hardening continues.
Signatures
ML-DSA-65 / FIPS 204
Key encapsulation
ML-KEM-1024 / FIPS 203
Hashing
SHA3-256 and SHAKE-256
Proofs
Transparent hash-based STARKs
Why a signature swap is insufficient
A blockchain depends on signatures in more places than wallet authorization. Validators sign votes, state transitions bind commitments and Merkle roots, private balances depend on encryption, and bridges verify the finality rules of two networks. Leaving any of those paths on a quantum-vulnerable primitive creates a weaker link.
SOS therefore treats post-quantum security as a protocol boundary. Transaction and consensus signatures use ML-DSA-65; note delivery uses ML-KEM-1024 with a SHAKE-derived authenticated-encryption key; commitments and nullifiers are hash based; and proofs verified by SOS are transparent STARKs with no trusted setup or pairings.
What the claim includes
The claim applies to the SOS-native side of the system. Canonical byte layouts and versioned domain tags keep signatures and hashes bound to one purpose. The active validator set is committed into the signed block hash, and the application state root binds transparent and shielded state.
- Wallet authorization and validator votes use ML-DSA-65.
- Shielded-note recovery uses ML-KEM-1024 sealed notes and view tags.
- SHA3-256 and SHAKE-256 provide hashing, commitments, nullifiers, and derivation.
- RISC Zero receipts carry proof results without exposing private witnesses.
The explicit external boundary
Ethereum compatibility is not described as post-quantum. Ethereum light-client verification and the EVM verifier necessarily follow the cryptography accepted by Ethereum. SOS isolates that compatibility boundary, documents it, and proves the state transition on each side rather than silently extending the Layer-1 claim across another chain.
The public testnet demonstrates the implemented architecture. It is evidence of integration and operability, not a substitute for independent review, long-running adversarial testing, or a mainnet security claim.
Questions
Common questions
Is Soul of Satoshi quantum-proof?
SOS is designed to be post-quantum across its native security boundary. The project uses the more precise term post-quantum because no implementation can promise immunity to every future cryptanalytic or software failure.
Does ML-DSA alone make a blockchain post-quantum?
No. Consensus votes, encryption, commitments, proof systems, key derivation, serialization, and external bridges must also be included in the threat model.
Is the Ethereum side post-quantum?
No. The bridge follows Ethereum's current verification rules at the external-chain boundary. That limitation is explicit and does not change the SOS-native construction.
Primary sources
Last reviewed: 2026-07-21