Cryptography
Public Key
Definition
The freely distributable half of an asymmetric key pair, used to encrypt messages for its owner or to verify digital signatures produced by the matching private key.
Examples
- An RSA or ECDSA public key embedded in a website's X.509 certificate.
- An SSH public key added to ~/.ssh/authorized_keys on a server.
Related terms
Private Key
The secret half of an asymmetric key pair, used to decrypt ciphertext addressed to its owner or to create digital signatures that prove the owner's identity.
Public-Key Cryptography
A branch of cryptography that uses paired public and private keys to enable encryption, key exchange, digital signatures, and authentication without a pre-shared secret.
Asymmetric Encryption
A cryptographic scheme that uses mathematically linked key pairs — a public key for encryption and a private key for decryption — to enable secure communication without prior secret sharing.
Digital Signature
A public-key cryptographic mechanism that proves the authenticity, integrity and non-repudiation of a message or document.
RSA Algorithm
A public-key algorithm by Rivest, Shamir and Adleman (1977) whose security rests on the difficulty of factoring the product of two large prime numbers.
Elliptic Curve Cryptography (ECC)
A family of public-key algorithms based on the algebraic structure of elliptic curves over finite fields, offering equivalent security to RSA with much smaller keys.