curve25519
also: Curve25519-Goldilocks, X25519, Ed25519
Curve25519 is an elliptic curve cryptography standard designed for fast, secure key exchange and digital signatures, widely used in modern Linux encryption tools.
Curve25519 is an elliptic curve developed by Daniel Bernstein in 2006, optimized for high performance and resistance to side-channel attacks. It operates over a 255-bit prime field, making it roughly equivalent to 128-bit symmetric security.
In Linux systems, Curve25519 is commonly used for Elliptic Curve Diffie-Hellman (ECDH) key exchange, allowing two parties to establish a shared secret over untrusted channels. It's the underlying mechanism in tools like ssh-keygen (Ed25519 keys) and wireguard VPN, providing faster and smaller keys than traditional RSA.
Example: When you generate a modern SSH key with ssh-keygen -t ed25519, you're creating a key pair based on Curve25519 math. This produces a compact 68-character public key instead of the much longer RSA equivalent.