Public-Key Cryptography
What is Public-Key Cryptography?
Public-Key CryptographyA branch of cryptography that uses paired public and private keys to enable encryption, key exchange, digital signatures, and authentication without a pre-shared secret.
Public-key cryptography, introduced by Diffie and Hellman in 1976, replaces a single shared secret with two mathematically linked keys: a public key that can be distributed openly and a private key that must remain confidential. The underlying security relies on problems believed to be computationally hard, such as integer factorization (RSA), the discrete logarithm in finite fields (DH, DSA) or on elliptic curves (ECDH, ECDSA), and lattice problems (Kyber, Dilithium). It provides three core capabilities: confidentiality through public-key encryption, authenticated key agreement, and digital signatures for integrity and non-repudiation. Because pure public-key operations are slow, they are typically combined with symmetric primitives in hybrid protocols like TLS, SSH, and S/MIME.
● Examples
- 01
X.509 certificates carry a public key and are signed by a Certificate Authority.
- 02
SSH uses public-key cryptography for passwordless server authentication.
● Frequently asked questions
What is 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. It belongs to the Cryptography category of cybersecurity.
What does Public-Key Cryptography mean?
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.
How do you defend against Public-Key Cryptography?
Defences for Public-Key Cryptography typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Public-Key Cryptography?
Common alternative names include: Asymmetric cryptography, PKC.