Cryptography and Security Fundamentals Glossary — 30 Core Terms

Asymmetric Cryptography

A cryptographic system using paired keys — a public key (shareable) and private key (secret) — where data encrypted with one can only be decrypted with the other. The foundation of blockchain wallet security.

Collision Resistance

A property of cryptographic hash functions where it should be computationally infeasible to find two different inputs producing the same hash output.

Deterministic Wallet

A wallet where all key pairs are derived from a single seed using a deterministic algorithm (BIP-32), allowing the entire wallet to be backed up with just the seed phrase.

ECDSA (Elliptic Curve Digital Signature Algorithm)

The signature algorithm used by Bitcoin and Ethereum, based on elliptic curve cryptography, providing strong security with relatively short keys.

Elliptic Curve Cryptography (ECC)

A class of public-key cryptography based on the mathematics of elliptic curves over finite fields, providing equivalent security to RSA with much smaller key sizes.

Hash Function

A function that converts input data of any size into a fixed-size output (hash), with properties including determinism (same input always produces same output), pre-image resistance (can't reverse-engineer input from output), and collision resistance.

HD Wallet (Hierarchical Deterministic)

A wallet structure (BIP-32) where a single master seed generates a tree of key pairs, allowing organized derivation of unlimited addresses from one backup.

Keccak-256

The specific hash function used by Ethereum (often confused with but technically different from the standardized SHA-3, which uses slightly different padding).

Merkle Proof

A compact cryptographic proof demonstrating that a specific piece of data is included in a Merkle tree, without needing to reveal the entire tree's contents.

Merkle Tree

A tree data structure where every leaf node is labeled with a data hash, and every non-leaf node is labeled with the hash of its children, enabling efficient and secure verification of large data structures.

Pre-image Resistance

A property of hash functions ensuring it's computationally infeasible to find an input that produces a specific given hash output.

Private Key

The secret cryptographic key that proves ownership and control over a blockchain address, enabling transaction signing. Must never be shared.

Public Key

The cryptographic key derived from (but not revealing) a private key, used to verify signatures and, after hashing, generate the public blockchain address.

SHA-256

A widely used cryptographic hash function producing 256-bit outputs, used by Bitcoin for proof-of-work mining and various other security applications.

Threshold Signature Scheme (TSS)

A cryptographic protocol allowing a group of parties to collectively produce a single signature, with the property that the signature is indistinguishable from one produced by a single key, even though the underlying key was never reconstructed in one place.

Trapdoor Function

A mathematical function that's easy to compute in one direction but difficult to reverse without special knowledge (the 'trapdoor'), foundational to public-key cryptography.

Zero-Knowledge Proof

A cryptographic method allowing one party to prove they know a value or that a statement is true, without revealing the value or any additional information beyond the statement's truth.

ZK-SNARK

Zero-Knowledge Succinct Non-Interactive Argument of Knowledge — a specific zero-knowledge proof construction providing very small proof sizes and fast verification, widely used in privacy-focused blockchain applications.

ZK-STARK

An alternative to ZK-SNARKs that doesn't require a trusted setup ceremony and offers better resistance to quantum computing attacks, though with larger proof sizes.