Definition
Quantum Computing Threats refer to the potential for quantum computers to break current cryptographic algorithms, particularly RSA and ECC, threatening the security of encrypted data, digital signatures, and secure communications.
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Common questions about Quantum Computing Threats answered by our security experts.
Quantum Computing Threats in Practice
The quantum risk is frequently discussed as a future problem, which misstates it. The decryption is in the future; the data capture is happening now. Encrypted traffic recorded today can be stored against the day a sufficiently capable machine exists — the “harvest now, decrypt later” pattern.
That reframes the deadline. It is not when quantum computers arrive. It is how long your data must stay confidential, counted backwards from that point.
Working out whether you are exposed
Three numbers decide it:
| Number | Question |
|---|---|
| Secrecy lifetime | How many years must this data stay confidential? |
| Migration time | How long will re-engineering our cryptography take? |
| Threat horizon | When might a cryptographically relevant machine exist? |
If secrecy lifetime plus migration time exceeds the threat horizon, you are already late. For most commercial data with a short confidentiality life this is comfortable. For health records, long-term contracts, state-relevant information or anything with a statutory retention measured in decades, it is not.
What actually breaks, and what does not
This distinction matters for planning. Your symmetric encryption at rest is broadly fine with adequate key lengths. The urgent work is key exchange and signatures — which is to say, essentially every TLS session, VPN tunnel and certificate you operate.
What to do now, in order
- Build a cryptographic inventory. Which algorithms, in which systems, with which key lengths, and who owns each. Almost nobody has this, and nothing else can be planned without it.
- Identify long-lived secrets — data whose confidentiality must outlast the threat horizon.
- Pursue crypto-agility. The ability to change algorithm without re-architecting is worth more than any specific algorithm choice, because the standards will continue to move.
- Ask vendors for roadmaps now, since much of your cryptography is in products you did not write.
- Prioritise hybrid key exchange where it is already available, which protects today's traffic against later decryption.
What your vendors should be able to tell you
Most of your cryptography is inside products you did not build, so a substantial part of this migration is a procurement exercise rather than an engineering one.
| Question | What a good answer sounds like |
|---|---|
| Which algorithms does the product use, and where? | A specific list, not a reassurance |
| Is the implementation crypto-agile? | Algorithm changeable without a re-architecture |
| What is your post-quantum roadmap and timeline? | Dates, and a named standard being tracked |
| Will migration require a hardware refresh? | Matters for anything with embedded cryptography |
| How are long-lived keys and certificates handled? | Rotation and lifetime, stated |
Embedded and industrial equipment is the awkward category. Devices with cryptography fixed in hardware and a fifteen-year service life cannot be migrated at all, so the answer there is compensating architecture rather than replacement.
Where to start
Identify the data you hold that must remain confidential for more than ten years. If that set is empty, this is a planning exercise. If it is not, the harvest-now risk applies to that data today and the inventory becomes urgent.
See encryption in practice. GuardsArm advises on cryptographic posture through security strategy.
Related Terms
Encryption
Encryption is the process of converting plaintext data into an unreadable ciphertext format using a cryptographic algorithm and key. Only authorized parties with the correct decryption key can convert the data back to its original readable form.
RSA Encryption
RSA is an asymmetric encryption algorithm that uses a pair of mathematically related public and private keys, widely used for secure data transmission, digital signatures, and key exchange in protocols like TLS/SSL.
TLS/SSL
TLS (Transport Layer Security) and its predecessor SSL (Secure Sockets Layer) are cryptographic protocols that provide secure, encrypted communication over networks, most commonly used to protect web traffic via HTTPS.
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