Cryptography

Cryptography is the science of securing information through mathematical transforms that render messages unintelligible to unauthorised parties while permitting intended recipients to recover the original data. Its core objectives encompass confidentiality—preventing unauthorised access; integrity—ensuring that data remain unaltered; authentication—verifying the identity of communicating parties; and non-repudiation—providing proof of message origin. Modern cryptography spans symmetric algorithms, where a single secret key encrypts and decrypts data, and asymmetric schemes, which employ mathematically linked public and private keys. In addition, advanced protocols harness quantum phenomena to certify security independently of device trustworthiness. Cryptographic primitives—such as block ciphers, hash functions, digital signatures and key-encapsulation mechanisms—are composed and deployed in modes matched to diverse applications, from secure internet transactions and cloud storage to post-quantum key exchanges and quantum-safe networks.

Research from Nature Portfolio

Generalised entropy-accumulation frameworks have been applied to device-independent quantum key distribution (DI-QKD), demonstrating that security against the most powerful collective attacks can be reduced to tractable numerical bounds. This advance proves that prepare-and-measure protocols need no entanglement-based reformulation to achieve composable security against arbitrary eavesdroppers under realistic finite-size conditions. Separately, a landmark result has shown that every real projective measurement can be self-tested via post-hoc and iterative protocols. This completes the toolkit for certifying uncharacterised quantum devices from observed Bell-violation statistics. On the experimental front, an event-ready DI-QKD link between independently trapped rubidium atoms separated by hundreds of metres has realised a loophole-free Bell test, achieving a positive asymptotic secret-key rate and closing detection loopholes at practical distances.

Cryptography publication trend

The graph below shows the total number of articles in cryptography across all publications each year (not limited to Nature Index journals).

Technical terms

Symmetric encryption: Encryption that uses the same secret key for both encryption and decryption.

Asymmetric encryption: Encryption using a public key to encrypt and a separate private key to decrypt.

Key-encapsulation mechanism (KEM): A protocol in which a symmetric key is securely shared by encapsulating it under an asymmetric scheme.

Device-independent QKD (DI-QKD): A quantum-cryptographic protocol whose security relies solely on Bell inequality violations, without trusting device internals.

Entropy accumulation: An information-theoretic method for bounding total secrecy by summing per-round randomness contributions.

Isogeny: A structure-preserving map between elliptic curves, whose hardness underpins supersingular isogeny schemes.

Bell inequality: A test quantifying non-local correlations; its violation certifies quantum security against classical attacks.

References

1. Security of quantum key distribution from generalised entropy accumulation. Nature Communications (2023).
2. All real projective measurements can be self-tested. Nature Physics (2024).
3. A device-independent quantum key distribution system for distant users. Nature (2022).
4. Towards High-Performance Supersingular Isogeny Cryptographic Hardware Accelerator Design. Electronics (2023).
5. SIKE on GPU: Accelerating Supersingular Isogeny-Based Key Encapsulation Mechanism on Graphic Processing Units. IEEE Access (2021).
6. A Compact and Scalable Hardware/Software Co-design of SIKE. IACR Transactions on Cryptographic Hardware and Embedded Systems (2020).