August 2025 | 13 min read
Quantum computing represents a revolutionary leap in processing power, but it also poses a threat to many of the encryption systems we rely on daily. In this article we'll explore:
- How traditional encryption is broken by quantum computing
- Post-quantum cryptography solutions
- Quantum key distribution (QKD) and its implications
- What the future holds for secure communications
The Quantum Threat
Quantum computers will be capable of breaking many of the encryption algorithms we currently rely on. Algorithms like RSA, ECC, and AES that secure everything from online banking to government communications are vulnerable to quantum algorithms like Shor's algorithm and Grover's algorithm.
Shor's Algorithm
Developed by Peter Shor in 1994, this quantum algorithm can factor large integers efficiently, breaking RSA encryption and many public-key cryptosystems.
Time complexity: O((log N)³) - exponential speedup over classical methods!
Grover's Algorithm
This quantum algorithm provides a quadratic speedup for searching unsorted databases and can be used to break symmetric key encryption.
Time complexity: O(√N) - makes AES vulnerable with 128-bit keys
Post-Quantum Cryptography
To combat this threat, researchers are developing quantum-resistant algorithms that can run on classical computers. The NIST Post-Quantum Cryptography Standardization project is making progress on developing these new standards.
Lattice-Based Crypto
Uses mathematical lattice problems that are hard for quantum computers to solve
Code-Based Crypto
Based on the hardness of decoding general linear codes
Multivariate Crypto
Uses multivariate polynomial equations
Quantum Key Distribution
An entirely different approach to secure communication, QKD uses quantum mechanics to securely share encryption keys. The most well-known QKD protocol is BB84, developed by Bennett and Brassard in 1984.
Quantum Communication Process
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Party A (Alice) sends quantum states (usually photons) through a quantum channel
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Party B (Bob) measures the quantum states randomly using different bases
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A and B publicly compare a subset of their measurement bases to determine the final key
While quantum computing threatens traditional encryption methods, it also offers new opportunities for secure communication. However, a quantum future won't be fully realized for years, and the transition to quantum-resistant algorithms will take time. In the meantime, organizations should:
- Start planning now for cryptographic migration
- Monitor NIST's post-quantum cryptography standards
- Develop hybrid cryptographic solutions