# Public Key Cryptography 1. A [[Cryptography|cryptographic]] system that uses both a [[private key ]] and [[public key]] to safeguard [[Transaction(s)|transactions]]. It's the central security-layer behind [[Crypto (cryptocurrency)|cryptocurrencies]] like [[bitcoin (BTC)|Bitcoin]]. 3. Encryption that uses two mathematically related keys. A public and private key. It is impossible to derive the private key based on the public key. 5. Public-key cryptography is a pair of keys used by a cryptographic system consisting of a public key and a private key. A public key may be circulated between many users, whereas a private key is known to the owner exclusively. There are two functions accomplished by public-key cryptography, public-key encryption (privacy) and [[Digital Signature| digital signatures ]] (authentication).