TL;DR
Post-quantum cryptography (PQC) discussions often focus on protecting encrypted data from future quantum attacks. Digital signatures face a different risk.
Recent IonQ research estimates that a future fault-tolerant quantum computer with around 20,000 physical qubits could break secp256k1, the elliptic-curve cryptography used for Bitcoin digital signatures, in approximately 26 days per attempt.
The research does not mean Bitcoin can be broken today. It provides a useful example of why PQC migration also needs to address the cryptography used for authentication and integrity.
IonQ’s Research on Digital Signatures
IonQ researchers examined the resources required to solve the elliptic-curve discrete logarithm problem for secp256k1 using Shor’s algorithm.
Their estimate requires 19,397 physical qubits and 1,457 logical qubits, with approximately 25.7 days required for each attempt.
IonQ says the required hardware scale is consistent with its public quantum computing roadmap around 2028. This is not a prediction that Bitcoin will be broken in 2028. No quantum computer capable of carrying out the modeled attack exists today.
Read IonQ research announcement
Encryption and Digital Signatures Face Different Quantum Risks
Store Now, Decrypt Later (SNDL) focuses on confidentiality. An attacker can collect encrypted information today and retain it until a sufficiently capable quantum computer becomes available to break the public-key cryptography protecting it.
Digital signatures serve a different purpose. They are used to authenticate transactions and verify that data or software has not been altered.
In the Bitcoin example studied by IonQ, a sufficiently capable quantum computer could use an exposed secp256k1 public key to derive the corresponding private key. This could allow an attacker to generate a valid digital signature without possessing the original private key.
PQC planning therefore needs to address both encrypted information and cryptographic mechanisms used for authentication and integrity.
Digital Signatures Are Used Across Enterprise Systems
Bitcoin is one example of elliptic-curve cryptography, but digital signatures are widely used across enterprise and government environments.
They can be found in digital certificates, authentication systems, code signing, software and firmware updates, PKI environments, and secure communications.
This creates a different migration challenge from simply identifying encrypted information. Signature algorithms can be embedded across applications and infrastructure, with dependencies that are not always visible to security teams.
For example, replacing a signature algorithm may require changes to an application, certificate infrastructure, hardware, or a software update process. A system may also depend on a commercial product that does not yet support the required post-quantum algorithm.
Organizations therefore need to understand not only which signature algorithms are in use, but also where they are used and which systems depend on them.
Some cryptography may be controlled internally. Other dependencies may be embedded in commercial software, hardware, or third-party services and require vendor support before migration is possible. Identifying these dependencies early can help organizations distinguish systems they can migrate directly from those that depend on external upgrade timelines.
Post-Quantum Digital Signature Standards Are Available
NIST finalized its first PQC standards in August 2024.
For digital signatures, these include ML-DSA under FIPS 204 and SLH-DSA under FIPS 205. Both are designed to provide digital signatures resistant to attacks from sufficiently capable quantum computers.
The availability of standards does not mean every existing system can immediately switch algorithms. Applications and infrastructure still need to support the new standards.
This makes standards adoption only one part of the migration problem. Organizations also need to determine whether existing applications, protocols, hardware, and third-party products can support the new cryptographic mechanisms and what changes may be required.
Cryptographic Discovery Needs to Include Digital Signatures
A cryptographic inventory should identify more than where encryption is used.
It should also provide visibility into quantum-vulnerable signature algorithms and the systems that depend on them.
For digital signatures, organizations should be able to determine which algorithms are present, where they are being used, and what applications or infrastructure depend on them. They also need to understand whether those cryptographic mechanisms can be changed internally or whether migration depends on a vendor, hardware refresh, or application upgrade.
This information can further turn cryptographic asset discovery into a practical basis for PQC migration planning.
A system using a quantum-vulnerable signature algorithm may be technically straightforward to update. Another may be tied to legacy infrastructure or a third-party product with a longer upgrade cycle.
Without visibility into these dependencies, both systems may appear as similar cryptographic findings even though their migration paths are very different.
A cryptographic inventory can help security teams move from simply identifying vulnerable cryptography to understanding where migration can begin and where additional planning is required.
IonQ’s research provides a current example of how quantum computing could affect digital signatures. For organizations preparing for PQC, the practical question is broader than whether one algorithm could eventually be broken.
The first step is knowing where quantum-vulnerable public-key cryptography exists across the environment and what will be required to replace it.
Sources
- IonQ, “IonQ Publishes World’s First Fully Compiled End-to-End Blueprint for Breaking 256-bit Elliptic Curve Signatures,” September 8, 2026.
IonQ Research Announcement - IonQ, “The First Full-Stack Blueprint for Breaking 256-Bit Elliptic-Curve Signatures,” September 8, 2026.
IonQ technical articles - Häner, T., Tripier, F., Young, J., et al., “Computing 256-bit elliptic curve discrete logarithms in 26 days on a fault-tolerant trapped-ion quantum computer with 20,000 qubits,” September 2026.
research paper - National Institute of Standards and Technology (NIST), Post-Quantum Cryptography.“
NIST Post-Quantum Cryptography
About CeQureX
CeQureX (CQX) helps organizations prepare for and manage the transition to post-quantum cryptography. The CQX Wave Series supports the PQC journey from cryptographic visibility and assessment through migration and ongoing cryptographic management.