Add BIP: QES2 – Hybrid PQC-based Digital Signature Algorithm #1830
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Would it make sense to just add QES2 support to BIP-360? |
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| QES2 can be integrated with BIP-340 (Taproot) by: | ||
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| 1. Using the QES2-based signature in place of the Schnorr signature |
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You specify QES2 as ECDSA, but ECDSA doesn't support all that Schnorr does. This seems like a step backwards that could break Taproot compatibility. Would it not make sense to implement QES2 with Schnorr and remove mention of ECDSA?
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Like @cryptoquick, I’m confused that this proposal focuses only on ECDSA signatures, when about 1/3 of all existing UTXOs use the P2TR output type that employs BIP340 signatures. Could you please provide rationale for this approach and further address the implications for existing P2TR outputs intended to be spent via the scriptpath?
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| 2. **ECDSA Security**: While vulnerable to quantum attacks, ECDSA remains secure against classical adversaries. | ||
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| 3. **Binding Property**: The ECDSA signature validates the Dilithium signature, creating a binding that requires breaking both schemes or finding hash collisions to forge. |
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Why is it necessary to sign the PQ signature? Can't it just be included separately and still benefit from the same guarantees if committed to in the same address as BIP-360 does?
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Hi @j1729labs, have you posted about this to the bitcoin-dev mailing list at https://groups.google.com/g/bitcoindev? Please refer to https://github.com/bitcoin/bips/blob/master/bip-0002.mediawiki#user-content-BIP_workflow for details. Thanks! |
murchandamus
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Thanks for your submission. The content of this document shows potential, however it is still lacking some important details (see other review comments). It also currently does not meet the formatting requirements for the BIPs process. Please fix the formatting to conform to the MediaWiki syntax and amend the Preamble to use preformatted text with the required formatting.
As this document is currently not ready to be merged, I’m turning it into a Draft pull request at this time.
| New Opcode | ||
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| We introduce a new opcode, tentatively assigned as ``OP_QES2_CHECKSIG (0xba)``, that performs verification of the hybrid QES2 signature by checking both the ECDSA signature (which validates the PQC signature) and the Dilithium signature itself. |
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Opcode 186 was designated OP_CHECKSIGADD by BIP 342.
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| QES2 can be integrated with BIP-340 (Taproot) by: | ||
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| 1. Using the QES2-based signature in place of the Schnorr signature |
There was a problem hiding this comment.
Like @cryptoquick, I’m confused that this proposal focuses only on ECDSA signatures, when about 1/3 of all existing UTXOs use the P2TR output type that employs BIP340 signatures. Could you please provide rationale for this approach and further address the implications for existing P2TR outputs intended to be spent via the scriptpath?
| This BIP maintains backward compatibility through several mechanisms: | ||
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| 1. **Opt-in Deployment**: QES2 addresses are distinct from traditional addresses | ||
| 2. **Traditional Scripts**: Existing P2PKH, P2SH, P2WPKH, and P2WSH scripts continue to function normally |
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As mentioned, this does not address P2TR outputs which make up about 1/3 of all existing UTXOs.
| Acknowledgments | ||
| ============== | ||
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| This proposal builds on the work of several other BIPs, including BIP-340, BIP-341, and BIP-342 (Taproot), and incorporates concepts from ongoing research in post-quantum cryptography for blockchains. |
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I’m confused that this proposal mentions BIP 340 several times, but insufficiently addresses BIP 340 signatures.
| This BIP introduces a new script template: | ||
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| .. code-block:: | ||
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| <pq_signature_push> <ecdsa_signature_push> <pubkey_push> OP_QES2_CHECKSIG |
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Please provide more detail how this new script template would be used in transactions. How is it split between output script, input script, witness section, or a newly introduced transaction section? How would this transaction be serialized? If it is intended to be a soft fork, what mechanism is used to allow unupgraded nodes to accept transactions using this signature scheme?
| :BIP: Unassigned | ||
| :Title: QES2 - A Hybrid Post-Quantum and Classical Digital Signature Scheme for Bitcoin | ||
| :Author: [Caleb Lee] [email protected], [Justin Park] [email protected], [Eunice Lee] [email protected], [Sophia Shim] [email protected] | ||
| :Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-XXXX | ||
| :Status: Draft | ||
| :Type: Standards Track | ||
| :Created: 2025-04-18 | ||
| :License: BSD-2-Clause | ||
| :Requires: 340, 341, 342 |
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The document must start with the preamble adhering to the required format. Beyond the formatting needing to be amended, the title is too long and the authors need to be on separate lines with the format Name <[email protected]>.
Summary:
This pull request introduces a new Bitcoin Improvement Proposal (BIP) for QES2, a hybrid digital signature algorithm that combines post-quantum cryptography (PQC) with traditional ECDSA. The proposal aims to address the potential vulnerabilities posed by quantum computing while preserving backward compatibility with existing Bitcoin infrastructure.
Details:
Abstract: QES2 leverages a dual-signature mechanism to incorporate both a post-quantum signature and a classical ECDSA signature into Bitcoin transactions.
Motivation: With the emerging threat of quantum computers, classical cryptographic methods may become vulnerable. QES2 presents a transitional solution that enhances security during the shift towards quantum-safe systems.
Specification: The BIP outlines the structure, key generation, signing, and verification methods for the hybrid scheme.
Rationale: The hybrid approach ensures that if one signature method is compromised, the other still provides protection, offering a balanced trade-off between security and backward compatibility.
Reference Implementation: A reference implementation will be linked later for further review and testing.