Why This Matters
A shift in computing is a shift in trust
Quantum computing can change the efficiency of solving certain problems, not what is computable in general. Its implications for digital trust are part of what learners need to understand.
The Quantum Shift
Classical computers
Classical machines store information as bits, each either 0 or 1. Their algorithms may solve problems efficiently and use parallel processing; they do not universally enumerate every possibility in sequence.
Quantum computers
Quantum machines use qubits, which can hold a combination of states until measured. Carefully designed algorithms use interference to obtain useful measurement outcomes. They do not simply try and read all possible answers at once.
Why quantum matters
Quantum computers are not general replacements for laptops. Advantage depends on the algorithm, suitable hardware and the problem. Some algorithms offer better theoretical efficiency, including for problems used in public-key cryptography; this is not a claim that today's hardware can break deployed systems.
1940s
Classical computing
Machines built on bits: every value is a definite 0 or 1.
1970s
Public key cryptography
RSA and related systems make secure communication at scale possible.
1994
Shor's Algorithm
A quantum algorithm for efficient factoring and discrete logarithms establishes a conditional threat to RSA and other public-key systems.
2020s
Quantum hardware research
Processors remain under development; no publicly known cryptographically relevant quantum computer currently exists.
2024+
Post-quantum standards
Standardized key establishment and digital signature methods support migration on classical systems.
The Quantum Threat
RSA and public-key cryptography. RSA's security relies on the difficulty of factoring large integers. Other threatened public-key systems rely on discrete logarithms, including on elliptic curves. These systems support key establishment and signatures in many services; factoring is not what protects all data, and not all encryption is affected in the same way.
Shor's Algorithm. In 1994 a method was published for efficient factoring and discrete logarithms on a sufficiently capable quantum computer. It poses a conditional future threat to RSA and those other public-key systems. No publicly known cryptographically relevant quantum computer currently exists, and this does not predict an arrival date. Symmetric encryption is a different case and is not broken by Shor's algorithm.
Harvest now, decrypt later. Encrypted data that adversaries obtain and that is protected by vulnerable cryptography may be stored for possible future decryption if sufficiently capable machines become available. This is a risk, not proof that all long-lived confidential data is already exposed. Prioritize long-lived sensitive information based on its protection and risk, not a universal ten-year threshold.
Post-Quantum Cryptography. PQC replaces the vulnerable mathematics with problems believed to be hard for both classical and quantum computers. PQC runs on classical systems; standardized methods include key establishment and digital signatures, not only encryption. Schools should work with technology vendors to understand dependencies, migration plans and appropriate priorities for long-lived sensitive information.
Official ASD guidance: Planning for post-quantum cryptography
Why Schools Should Care
Existing cyber education is a strong behavioural foundation. A quantum-safe future asks schools to build depth behind those habits.
Current cyber education often focuses on
- Passwords
- Phishing
- Online safety
Future cyber education should also include
- Cryptographic resilience
- Digital trust
- Emerging technologies
- Quantum-safe systems