Definition
Cryptography provides tools for securing information and communication. Its functions include confidentiality, integrity and authentication. Encryption is one part of cryptography, but the field also includes hashing, digital signatures and other constructions. Describing a system as cryptographic does not mean all of its data is encrypted or private.
Role in Blockchain
Digital signatures help demonstrate that a transaction was authorized by a corresponding key. Hashes help identify data and connect records, while specialized proofs can establish properties without revealing all underlying information. These tools operate alongside consensus rules and software checks; cryptography alone does not determine which competing chain is accepted.
Key Considerations
Security depends on the chosen construction, assumptions, implementation and handling of keys. A strong algorithm can be undermined by weak randomness, exposed secrets or misleading user interfaces. Publicly verifiable transactions can still reveal sensitive patterns. Cryptography also cannot force an external issuer to honor a promise or guarantee the correctness of an oracle’s input. Evaluating a blockchain therefore requires looking beyond the names of its cryptographic algorithms.