ACE Seminar: Hash-Based Post-Quantum Signatures Tailored to Blockchains

Speaker: Konstantinos Chalkias

Date/Time: 06-Dec-2018, 16:00 UTC

Venue: Robert 3.09



This talk will focus on how to efficiently build post-quantum secure blockchains from hash functions and nothing else. Kostas will present the BPQS protocol, an extensible post-quantum signature scheme best suited to blockchain and distributed ledger technologies (DLTs). One of its unique characteristics is that it can take advantage of application-specific chain/graph structures in order to decrease key generation, signing and verification costs as well as signature size. Compared to recent improvements in the field, BPQS outperforms existing hash-based algorithms when a key is reused for reasonable numbers of signatures, while it supports a fallback mechanism to allow for a practically unlimited number of signatures if required. It’s also very simple to be implemented. If time allows, we will also mention some attacks on existing post-quantum blockchains (i.e., IOTA), and why blockchains have not been well-designed to allow forks.


Kostas is a Cryptographer and Platform Engineer at R3 and he is well known in the fintech sector by participating in various blockchain proof of concepts with the major financial institutes. He is currently focusing on applying advanced encryption, cross chain atomic swaps, post-quantum digital signatures and zero knowledge proofs to Corda blockchain and he has proposed some of the fastest protocols in the fields of timed-release encryption and graphical passwords. After jumping to business from academia in 2010, he initially worked as the Lead Security Engineer in two big data and natural language processing start-ups and he filed a couple of patents in the fintech and cryptography sectors.

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