Qbit preserves the core proof-of-work UTXO model while redesigning the parts that post-quantum security changes: spend authorization, transaction weight, block limits, relay behavior, storage, mining, and wallet operations.
Key Specs
The active spend profile, block envelope, mining cadence, and monetary cap that shape Qbit.
Foundation
The base architecture separates Qbit from legacy balance migration and treats post-quantum costs as first-order consensus inputs.
Qbit is not a continuation of Bitcoin's chain, UTXO set, or balances. It is a new network with its own genesis block, monetary policy, consensus rules, and asset. Its implementation is derived from Bitcoin Core v30.2, giving Qbit a mature node foundation while applying new consensus and wallet architecture for post-quantum operation.
Post-quantum signatures are larger than classical signatures, and that affects the whole system. Qbit treats this as a base-layer design constraint rather than an afterthought.
Large signatures change transaction size. Transaction size changes fees, mempool pressure, propagation, block limits, storage, and wallet behavior. Qbit's architecture is built around those dependencies directly.
Spend Layer
P2MR outputs and hash-based authorization work together so unused spend paths are not exposed while funds remain at rest.
Qbit uses SLH-DSA-SHA2-128s-bounded30 as its active post-quantum spend profile. The active signature size is 3,680 bytes, making spend authorization resistant to the discrete-log attacks that threaten elliptic-curve signatures.
This gives Qbit a conservative hash-based signature path while keeping the base layer focused on simple, verifiable UTXO spends.
Qbit uses Pay-to-Merkle-Root, or P2MR, for spendable outputs. Instead of placing a public key or spend script directly on-chain, an output commits to a 32-byte Merkle root.
When funds are unspent, public spend keys and unused spending paths remain hidden. When funds are spent, only the selected spend path is revealed and verified through OP_CHECKSIGPQC.
Resource Model
The block envelope and witness accounting stay explicit, so validation and relay costs remain visible to users and node operators.
Qbit does not hide large post-quantum witnesses behind discounted accounting. Witness bytes are priced directly with WITNESS_SCALE_FACTOR = 1, meaning serialized size and block weight move together.
This keeps fees, validation cost, network propagation, and storage pressure aligned with the real cost of post-quantum transactions.
Qbit uses a 2,000,000-byte / 2,000,000-weight block envelope. This gives the network explicit limits for propagation, validation, and storage growth.
The result is a deliberate throughput model: Qbit prioritizes durable post-quantum security and practical node operation over pretending large signatures have no cost.
Mining And Supply
Native SHA-256 mining and AuxPoW blocks feed the same most-work chain while issuance remains deterministic and mining-only.
Qbit has one chain selected by most accumulated work. Blocks can come from two mining paths:
The permissionless lane keeps participation open. The AuxPoW lane allows Qbit to draw security from Bitcoin-linked SHA-256 hashrate without creating a separate ledger or fork-choice rule.
Qbit targets a one-minute aggregate block cadence through two lane schedules:
Difficulty adjusts continuously using ASERT with a two-hour halflife, allowing the network to respond smoothly to hashrate changes instead of waiting for long retargeting epochs.
Qbit uses deterministic issuance with a 210,000,000 QBT consensus cap. The initial subsidy is 210 QBT, with stepwise subsidy decay every 43,200 blocks.
Distribution is mining-only. There is no premine, no outside allocation, and no later legacy-balance migration required to move users into post-quantum-safe outputs.
Operations
The operational model makes witness storage, key rotation, and future spend-path upgrades visible instead of burying them in wallet assumptions.
Large witnesses make long-term node operation part of the architecture. Qbit supports archive-retaining nodes and explicit witness-pruned operation.
Archive nodes preserve historical witness data for deep replay and recovery. Witness-pruned nodes can validate the active chain and maintain current chainstate without storing every historical witness forever.
Post-quantum wallets have different operational requirements. Qbit wallets must track per-key usage, rotate keys before limits are reached, and handle watch-only workflows through explicit public-key export rather than classical public derivation.
For exchanges, custodians, and payment processors, confirmation policy should be based on Bitcoin-equivalent settlement security, not a fixed raw Qbit block count.
Qbit keeps the base layer narrow. Spendable outputs are restricted to the post-quantum transaction model, with reserved witness versions and P2MR leaf codes available for future soft-fork upgrades.
This allows Qbit to evolve as post-quantum signature technology improves without broadening the active spend surface unnecessarily.
Explore the full Qbit design, including post-quantum signatures, mining, supply, witness accounting, and long-term validation.
