Frequently Asked Questions

QSBitcoin is a work-in-progress quantum-safe implementation of Bitcoin Core v28.0 that adds NIST-standardized post-quantum signatures while maintaining full backward compatibility. It protects against future quantum computer attacks using ML-DSA-65 and SLH-DSA-192f signature algorithms, implemented via a soft fork with unified opcodes (OP_CHECKSIG_EX and OP_CHECKSIGVERIFY_EX).

Traditional cryptocurrencies like Bitcoin use cryptographic algorithms (such as ECDSA for digital signatures) that are vulnerable to attacks from sufficiently powerful quantum computers. As quantum computing technology advances, these vulnerabilities become more concerning.

Specifically, quantum computers could potentially:

• Break the digital signature schemes used to secure transactions
• Derive private keys from public keys, allowing unauthorized access to funds
• Compromise the security of the blockchain as a whole

QSBitcoin addresses these concerns by implementing quantum-resistant cryptographic algorithms that are believed to be secure even against attacks from quantum computers.

QSBitcoin achieves quantum safety through:

• NIST-Standardized Algorithms: ML-DSA-65 (Module-Lattice Digital Signature Algorithm) for standard transactions and SLH-DSA-192f (Stateless Hash-Based Digital Signature Algorithm) for high-value cold storage.
• Unified Opcodes: Just two new opcodes (OP_CHECKSIG_EX and OP_CHECKSIGVERIFY_EX) support all quantum algorithms, with the algorithm identified by the first byte of the signature data.
• Soft Fork Implementation: Fully backward compatible - both ECDSA and quantum signatures are accepted, allowing users to migrate at their own pace.
• P2WSH Addresses: Quantum addresses use standard bech32 format (bc1q...), indistinguishable from regular Bitcoin addresses for privacy.

Yes! QSBitcoin is implemented as a soft fork of Bitcoin Core, meaning:

• Full Backward Compatibility: Non-upgraded nodes see quantum transactions as valid (anyone-can-spend)
• Same Network: QSBitcoin operates on the Bitcoin network, not a separate blockchain
• Mixed Transactions: Support for both ECDSA and quantum signatures in the same transaction
• Standard Addresses: Quantum addresses use regular P2WSH format (bc1q...)
• Existing Tools: Most Bitcoin tools work with QSBitcoin, though quantum signing requires updated software

Currently active on testnet and regtest networks, with mainnet activation pending community consensus.

Creating quantum-safe addresses is simple with QSBitcoin Core:

• ML-DSA Address: bitcoin-cli getnewaddress "" "bech32" "ml-dsa"
• SLH-DSA Address: bitcoin-cli getnewaddress "" "bech32" "slh-dsa"

Key differences:

• ML-DSA: ~3.3KB signatures, recommended for 99% of users
• SLH-DSA: ~35KB signatures, for high-value cold storage

Both address types look like standard Bitcoin bech32 addresses but use quantum-safe signatures internally.

Signature Algorithms:

• ML-DSA-65: 1,952 byte pubkey, ~3,309 byte signature, NIST Level 3
• SLH-DSA-192f: 48 byte pubkey, ~35,664 byte signature, NIST Level 3

Implementation Details:

• Base: Bitcoin Core v28.0
• Library: liboqs v0.12.0+
• Opcodes: OP_CHECKSIG_EX (0xb3), OP_CHECKSIGVERIFY_EX (0xb4)
• Script Flag: SCRIPT_VERIFY_QUANTUM_SIGS (bit 21)
• BIP9 Deployment: Bit 3
• Max TX Weight: 1MB for quantum transactions

QSBitcoin is under active development:

• 🚧 Core Features: Quantum addresses can generate, receive, and spend funds on testnet/regtest
• 🚧 Test Coverage: Comprehensive test cases across multiple test files
• 🚧 Network Status: Active on testnet and regtest networks for testing
• ✅ Unified Opcodes: Implemented 2 unified opcodes for all quantum algorithms
• 🚧 Documentation: Technical specification being refined

Mainnet activation awaits community consensus on deployment parameters.

While quantum computers capable of breaking ECDSA don't exist yet, consider migrating because:

• Future-Proofing: Quantum addresses are immediately quantum-safe upon creation
• Standard Fees: Fees based on transaction size (larger signatures mean higher fees)
• No Forced Migration: You control when to switch - ECDSA continues to work
• Store of Value: Past transaction data could become vulnerable when quantum computers arrive
• Early Adoption: Help test and improve the quantum-safe infrastructure

Migration is as simple as generating a new quantum address and transferring funds.

QSBitcoin provides a complete implementation guide for developers:

• Source Code: github.com/qsbitcoin/qsbitcoin
• Technical Spec: Comprehensive Spec.md in the repository
• RPC Extensions: New commands like getquantuminfo, extended getnewaddress
• Implementation Guide: Step-by-step instructions for compatible forks
• Test Suite: 88 test cases to verify your implementation

Key areas for contribution: wallet integration, block explorers, lightning network support, and optimization of quantum signature verification.

QSBitcoin's unique approach includes:

• Soft Fork Implementation: Works on the Bitcoin network, not a separate blockchain
• Unified Opcodes: Just 2 opcodes support all quantum algorithms (vs 4+ in other designs)
• NIST Standards: Uses only NIST-standardized algorithms (ML-DSA, SLH-DSA)
• Active Development: Core features functional with ongoing development
• Standard Fees: Fair fee structure based on blockchain resource usage
• MIT Licensed: Fully open source for maximum transparency

Unlike altcoins, QSBitcoin enhances Bitcoin rather than replacing it, preserving network effects while adding quantum resistance.