First Post-Quantum Transaction Confirmed on Marsqnet
A Transaction Unlike Any Before It
On April 20, 2026, the Marscoin network confirmed its first post-quantum transaction on the marsqnet development network. Transaction a959d518... carried a SPHINCS+ digital signature — a hash-based cryptographic proof that no quantum computer, present or future, can forge.
The transaction moved testnet coins from one quantum-resistant address (mqt1z...) to another, making it the first PQ-to-PQ transfer on a Bitcoin-derived chain. Every byte of the cryptographic proof relies solely on SHA-256 — the same primitive that secures proof-of-work mining. No elliptic curves. No lattice assumptions. Just hash functions.
What Made This Transaction Different
A standard Marscoin transaction carries an ECDSA signature of roughly 72 bytes. This transaction carried a SPHINCS+ signature of 7,857 bytes — over 100 times larger — packed into a witness v2 data structure that the network validated and confirmed in a single block.
| Property | Standard Transaction | Quantum Transaction |
|---|---|---|
| Signature scheme | ECDSA (secp256k1) | SPHINCS+ (SLH-DSA-SHA2-128s) |
| Signature size | ~72 bytes | 7,857 bytes |
| Transaction size | ~234 vBytes | 2,103 vBytes |
| Security basis | Elliptic curve (Shor-vulnerable) | SHA-256 only (quantum-safe) |
| Address format | mars1q... | mars1z... (witness v2) |
| NIST standard | — | FIPS 205 |
The larger signature is accommodated by Marscoin’s adaptive block weight limit (ABWL), which dynamically adjusts block capacity based on network demand — technology adapted from Bitcoin Cash’s production-proven ABLA algorithm.
The Technical Stack
This transaction exercised a complete post-quantum infrastructure built over the preceding weeks:
Consensus layer: A new witness version (v2) was added to the script interpreter, enabling nodes to verify SPHINCS+ signatures as part of block validation. The output format — OP_2 <SHA256(parameter_set_id || public_key)> — hides the public key until spend time, providing quantum protection for coins at rest.
Wallet layer: A new RPC command (getnewpqaddress) generates SPHINCS+ keypairs via the vendored liboqs backend, stores them in the wallet database, and returns mars1z... addresses encoded in bech32m format.
Signing layer: When spending from a quantum address, the wallet constructs a three-element witness stack — the 7,857-byte signature payload, the parameter set identifier, and the 32-byte public key — signed using the NIST-standardized SLH-DSA-SHA2-128s algorithm.
Mining layer: The marsqnet development network uses RandomX proof-of-work for CPU-egalitarian block production, with an adaptive block weight limit that scales capacity as post-quantum transactions enter the network.
What This Means
Marscoin is now among the first Bitcoin-derived cryptocurrencies to execute a native, consensus-level post-quantum transaction. This is not a sidechain, not a smart contract, not a theoretical proposal — it is a confirmed transaction on a live network, validated by every node.
The quantum threat to elliptic curve cryptography is no longer hypothetical. Google’s March 2026 research demonstrated private key derivation from exposed public keys in approximately nine minutes. NIST has finalized post-quantum standards and federal agencies are submitting migration plans.
Marscoin’s response: working code, running on a testnet, producing real quantum-resistant transactions.
Try It Yourself
The marsqnet quantum faucet is live. Visit the marsqnet explorer to request testnet coins sent to a quantum-resistant address.
The full Quantum Upgrade Proposal details the roadmap, and the technical comparison explains why Marscoin chose SPHINCS+ over alternatives like Bitcoin Cash’s Quantumroot.
All code is open source on the feature/quantum-upgrade branch.
This milestone was achieved on the marsqnet development network. Mainnet activation will follow community review, external audit, and a coordinated hard fork. Testnet coins carry no real value.
