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What is cryptography?
Cryptography is the use of mathematics to keep information secret, prove who created something and detect whether data was changed. In crypto, it is what lets a private key approve payments and lets every computer on the network check them without having to take anyone's word for it.
What it means for you
The network accepts any transaction correctly signed with your private key, whoever sends it, and rejects every other one. The mathematics cannot tell a thief from you, so the weak point is usually where the key is kept, not the cryptography itself.
A common mistake: “Crypto is called crypto because the payments are encrypted and hidden.”
In fact: The name comes from cryptography, but on Bitcoin and Ethereum it mainly signs and fingerprints data. Amounts and addresses are published openly; a signature proves who approved a payment without hiding it.
How it works
NIST describes cryptography as the discipline that provides confidentiality, data integrity, source authentication and non-repudiation. Blockchains lean mostly on the last three. Hash functions make any change to data detectable, and digital signatures prove that the holder of a private key approved a transaction. Security rests on problems believed computationally infeasible: given a public key, deriving the private key is designed to be impractical. Confidentiality plays little part in Bitcoin and Ethereum: a signature gives integrity and authenticity but, as NIST notes, not confidentiality, so a signed transaction stays readable by anyone.
Sources: NIST CSRC glossary: cryptography, NIST CSRC glossary: public key cryptography, NIST CSRC glossary: digital signature · checked 4 October 2026
Often confused with
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