Cryptography
Cryptographic primitives, algorithms, and protocols used in blockchain
Key Glossary Terms
Essential vocabulary for this topic
AES
intermediateA widely used symmetric-key encryption algorithm for protecting data confidentiality.
AES Encryption
intermediateAdvanced Encryption Standard (AES) is a symmetric-key block cipher algorithm established by the U.S. National Institute of Standards and Technology (NIST) in 2001. It operates on fixed-size blocks of data, typically 128 bits, using key lengths of 128, 192, or 256 bits. AES utilizes a substitution-permutation network design, performing multiple rounds of transformation to convert plaintext into ciphertext, making it highly resilient against cryptanalysis. It is the global standard for securing sensitive data in transit and at rest.
Cryptography
Algorithm
intermediateA cryptographic algorithm is a precise, step-by-step mathematical procedure or set of rules designed to perform specific security tasks, such as encryption, decryption, digital signature generation, or hashing. These algorithms form the bedrock of blockchain technology, ensuring data integrity, transaction authentication, and network consensus. By relying on rigorous mathematical proofs, these protocols enable trustless systems to operate securely across decentralized and distributed environments without the need for a central clearing authority.
Cryptography
Asymmetric Cryptography
intermediateAsymmetric cryptography, also known as public-key cryptography, is a cryptographic system that uses pairs of mathematically related keys: a public key, which may be disseminated widely, and a private key, which is kept secret. The system relies on computational complexity, specifically the difficulty of factoring large prime numbers or solving discrete logarithm problems. Data encrypted with a recipient's public key can only be decrypted with the corresponding private key, ensuring confidentiality, while digital signatures created with a private key can be verified by anyone with the public key, ensuring authenticity and non-repudiation.
Cryptography
Asymmetric Encryption
intermediateEncryption that uses a mathematically related public and private key pair instead of one shared secret.
BIP32
advancedBitcoin Improvement Proposal 32 (BIP32) defines the standard for Hierarchical Deterministic (HD) wallets. It provides a system where a single master seed can generate a tree structure of unlimited keys and addresses. By using a parent extended key to derive child keys, BIP32 allows users to manage multiple accounts or addresses using only one backup phrase. This structure includes hardened derivation, which prevents the compromise of a child key from exposing the parent key, significantly enhancing security and operational convenience for multi-asset management.
Cryptography
Research Papers
Academic and industry research
Verifiable Random Functions
Silvio Micali, Michael Rabin, Salil Vadhan
This seminal paper introduces the concept of a Verifiable Random Function (VRF), a cryptographic primitive that provides a publicly verifiable proof of correctness for a pseudorandom output. Unlike standard pseudo-random functions (PRFs), a VRF allows a user to generate a random value along with a non-interactive proof. Any third party, possessing the prover's public key, can verify that the generated value is indeed the correct result of the function applied to a given input, without needing to know the secret key or the internal state of the generator. The authors establish the formal definitions, security properties—namely uniqueness, collision resistance, and pseudorandomness—and propose concrete constructions. The VRF has become a foundational building block in blockchain systems, providing a mechanism for leader election, random number generation in smart contracts, and efficient proof-of-stake selection processes. By enabling verifiable unpredictability, VRFs resolve critical challenges in distributed systems that require trustless random sources that cannot be manipulated by participants, ensuring fairness and security in decentralized protocols.
How to Share a Secret
Adi Shamir
Adi Shamir's paper introduces 'Shamir's Secret Sharing,' a mathematical method for partitioning a secret into several pieces, such that the secret can only be reconstructed when a defined number (a threshold) of pieces are provided. This work has become a cornerstone of blockchain security, specifically in the context of multi-party computation (MPC), social recovery wallets, and distributed key management systems (DKMS). By avoiding a single point of failure for sensitive private keys, secret sharing allows for more resilient security architectures that align with the decentralized ethos of blockchain. The paper uses the theory of polynomial interpolation to demonstrate how to achieve this threshold-based access, offering a robust and elegant solution to the challenge of secret protection. In Web3, this methodology is now central to developing non-custodial solutions that offer institutional-grade security for individuals, ensuring that users have the power to retain control of their digital identity without the risk of single-point compromise.
Hashcash - A Denial of Service Counter-Measure
Adam Back
Adam Back’s Hashcash proposal outlines a mechanism for limiting email spam and denial-of-service attacks by requiring a small computational 'cost' for each outgoing communication. This mechanism involves finding a partial hash collision, effectively requiring a sender to perform a predictable amount of computational work, now widely known as Proof of Work (PoW). The paper proposes a decentralized, trustless way to throttle automated behavior, an idea that profoundly influenced Satoshi Nakamoto when designing the Bitcoin protocol. Hashcash provides the fundamental answer to the 'Sybil problem' in distributed networks, establishing that proof of resource expenditure (CPU time) can serve as a proxy for social or economic cost. By grounding the protocol in the difficulty of finding specific hashes, Hashcash created the economic incentives necessary to maintain a decentralized ledger, fundamentally shaping the trajectory of blockchain technology and cryptocurrency consensus mechanisms.