Ledger CTO Warns Bitcoin Quantum Migration Could Take Years as SHRINCS Emerges

• Ledger CTO Charles Guillemet published a technical analysis on September 16, 2026, evaluating the SHRINCS post-quantum signature proposal.
• The SHRINCS draft specifies signature sizes ranging from 548 to 5,777 bytes, compared to the 64 to 72 bytes seen in current ECDSA and Schnorr schemes.
• The proposal combines stateful signatures using Flexible XMSS and WOTS+C with a stateless fallback mechanism backed by SHA-256.

Charles Guillemet, Chief Technology Officer at Ledger, warned that the Bitcoin quantum migration is not an immediate hardware threat, but rather a protracted technical coordination challenge that could take years. The statement was issued this Wednesday, September 16, following an evaluation of the SHRINCS improvement proposal.

Through a technical publication, Guillemet noted that the current custody framework relies on digital signatures that would be compromised by a cryptographically relevant quantum computer. A source reported that the specialist argued waiting for such hardware to emerge would represent an operational risk, given the extensive timeline required for research, testing, and network-wide deployment.

The evaluated framework, designated as SHRINCS, is a draft Bitcoin Improvement Proposal (BIP) authored by Conduition, Ethan Heilman, Mikhail Kudinov, Oleksandr Kurbatov, Jonas Nick, and remix7531.