SCF #13
Award Completed
An Efficient Scaling Mechanism for Lattice-Based Post-Quantum Signatures

Offers a scaling solution to improve transaction verification speed and cost savings by leveraging zero-knowledge proofs.

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March, 2021
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The general principle of this project is to explore the possibility of replacing pre-quantum digital signatures, which are vulnerable to attacks by quantum computers, with post-quantum digital signatures. These signatures are designed to be resistant to quantum attacks and could provide a more secure foundation for Stellar in the future.


Implementing post-quantum cryptography in blockchains has several downstream consequences. Signature sizes associated with the standardized post-quantum digital signature algorithms are much larger than the signatures used in blockchains today. Even with the smallest NIST post-quantum digital signatures, public-keys and digital signatures would consume at least 21x and 24x larger than the signatures used in Bitcoin and Ethereum, respectively.

Since every blockchain transaction needs to be signed with a digital signature, each transaction will occupy more space within a block. This means that there will be fewer transactions per block, which results in slower transaction speeds for users and higher gas fees to include their transactions into the highly competitive block. By implementing post-quantum cryptography in blockchains, we are effectively unscaling our blockchains.


Our service is designed to aggregate the post-quantum digital signatures associated with multiple transactions in a block. This will allows the Stellar blockchain to reduce the overhead cost of storing one post-quantum digital signature per transaction, thereby significantly reducing the size of each block. This technique preserves the structure of all existing transaction data and simply replaces the digital signatures associated with each transaction with a single aggregate signature. The output of this project will be a publicly accessible paper summarizing the research outcomes.

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First Deliverable

Our team will demonstrate a clear understanding of post-quantum lattice-based digital signature aggregation and explain it effectively in a paper. We will also show our ability to implement, test and generate valid aggregate digital signatures using the constructed algorithms, compare the performance of the constructed algorithms with prior work, and document our methodology and results.

We will perform the following steps:

  1. Show a clear understanding of the construction for post-quantum lattice-based digital signature algorithms and the ability to explain it effectively in a paper (link).
  2. Show our ability to implement, test and successfully generate valid aggregate digital signatures using the construction for post-quantum lattice-based digital signature algorithms.
  3. Show our ability to compare the performance of the constructed post-quantum lattice-based digital signature algorithms with existing pre-quantum digital signature algorithms in terms of signature size, speed, and security.
  4. Document our methodology and obtained results.

Reviewer instructions

To check the completed items of the first deliverable, the reviewer may review the research paper submitted by the team, focusing on the methodology used to demonstrate the construction of post-quantum lattice-based digital signature algorithms, the results obtained from the implementation and testing of the algorithms, and the comparison with previous work. Additionally, they may look for clear and concise documentation of the methodology and results obtained in the research paper to ensure that the first deliverable has been completed successfully.

BTQ Technologies

BTQ was founded by a group of post-quantum cryptographers with an interest in addressing the urgent threat that a large-scale universal quantum computer poses to digital security. With the support of leading research institutes and universities, BTQ is combining software and hardware to safeguard assets with unique post-quantum services and solutions.


Chen-Mou Cheng

Chief Scientist

PhD from Harvard University in Computer Science; previous professor at National Taiwan University.

2348 citations and 24 h-index

Po-Chun Kuo

Chief Technology Officer

PhD from Institute of Electronics Engineering at National Taiwan University. Post-quantum cryptographer.

204 citations and 6 h-index

Jimmy Hu

Head of Software Engineering

B.Sc. and M.Sc. in Electronics Engineering at National Chiao Tung University.

Previously technology lead at COBINHOOD/DEXON.

Gavin Brennen

Quantum Advisor

Physic PhD, Director at Macquarie Centre for Quantum Engineering.

Former CCO at Qubit Protocol, 5000+ citations

Christopher Tam

Head of Partnerships

B.Sc. in Computer Science, M.Sc. in Software Engineering at Western University

Previously ML researcher and data engineer.

Our team is set up for success because:

Our team is well-positioned for success thanks to our extensive breadth of expertise and long-standing research in the field of post-quantum cryptography. We bring a wealth of knowledge and experience to the table, allowing us to develop innovative solutions that address the challenges associated with securing blockchain technology against quantum attacks. With our team's unique combination of skills and insights, we are confident in our ability to make meaningful contributions to this exciting and rapidly evolving field.