The Hidden Threat: Harvest-Now-Forge-Later and the Collapse of Digital Trust

Episode notes

As quantum computing advances, organizations can no longer view post-quantum cryptography as a future project. In this episode of Shielded: The Last Line of Cyber Defense, Konstantinos Karagiannis, Director of Quantum Computing Services at Protiviti, lays out a practical and attacker-focused perspective on preparing for the quantum era. Konstantinos explains why the industry’s fixation on harvest-now-decrypt-later misses the most serious exposure: harvest-now-forge-later, where quantum capability targets the foundation of digital trust through attacks on code signing, software update channels, and blockchain consensus mechanisms. He introduces the emerging Five-Day Rule, informed by recent research indicating that a cryptographically relevant quantum machine could break RSA-2048 in roughly five days, reshaping assumptions about risk and timelines. The discussion expands to the potential instability of blockchain networks, such as proof-of-stake systems reliant on BLS signatures, and the broader implications for market integrity and digital identity.