Overview
Cryptography refers to the mathematics of protecting data from being surreptitiously altered or accessed inappropriately. It is essential for most internet activity, including messaging, e-commerce, and banking. There are two main types of cryptography: symmetric and asymmetric. Symmetric cryptography requires both parties to share one secret key to encrypt and decrypt data. In practice, sharing this secret key can be difficult. This led to the development of asymmetric encryption, which uses one public key, freely available to anyone, to encrypt data and a different private key to decrypt data. Hashing is another cryptographic method that generates a unique fixed-length string of numbers for a given input. Through the combination of hashing and other techniques, cryptography also enables identity verification and allows a recipient to confirm that a message was not altered in transit.
KEY DEVELOPMENTS
BLOCKCHAIN
Blockchain technology employs cryptography to create a ledger that is secure and immutable. Each digital block in the blockchain contains a transaction and a cryptographic hash of the previous block, forming a chain. In this way, the blockchain is immutable, since changing earlier blocks would change the hashes and be easily detected. Blockchain technology has been applied to a variety of use cases:
- Identity Management: Blockchain securely stores a person’s essential documents (like tax returns and health records), allowing selective data disclosure upon request. Applications are already emerging for identity management using blockchain.
- Supply Chain Management: Blockchain offers a transparent way to track goods, their origins, and their quantities, benefiting industries with authenticity concerns, including ones involving high-value products such as diamonds and other luxury goods.
- Smart Contracts: These are programmable self-executing contracts stored
on the blockchain, eliminating the need for a third-party executor and
increasing transaction efficiency. - Transactional records: Any kind of transactional record can be stored on a
blockchain, thereby streamlining the process of buying and selling items by
reducing fraud, increasing transparency, and cutting paperwork. - Cryptocurrencies: Digital currencies like Bitcoin and Ethereum use blockchain technology to create tokens that can act as a form of currency that does not have to be regulated or controlled by any central authority.
SECURE COMPUTATION
Another important subfield of cryptography is secure computation, which enables multiple parties to contribute inputs to a function that they jointly compute without sharing their individual inputs with each other. Secure computation is extremely useful in financial and health settings where sharing individual client/patient data is unethical or even illegal.
Within secure computation are zero-knowledge proofs, which are cryptographic methods that allow one person to prove to someone else that he or she knows a specific piece of information without revealing to the other person any details about that information. The term “zero-knowledge” indicates that the receiver gains zero new knowledge about the information in question, apart from the fact that what the prover is saying is true. Zero-knowledge proofs have applications in banking, where a buyer may wish to prove to a seller the possession of sufficient funds for a transaction without revealing the exact amount of those funds. There are also applications ranging from cooperative tracking and verification of numbers of tactical nuclear warheads to checking provenance of digital images.
