ECDSA (Elliptic Curve Digital Signature Algorithm) is a cryptographic algorithm for digital signatures based on elliptic curves. At comparable security levels, ECDSA requires significantly shorter keys than RSA — a 256-bit ECDSA key is roughly equivalent to a 3072-bit RSA key.
ECDSA is used for TLS certificates, SSH keys, code signing, and blockchain transactions. Shorter keys speed up signature creation and verification, which is particularly beneficial on resource-constrained devices (IoT, smart cards). Common curves include P-256 (NIST) and Curve25519. For new systems, Germany’s BSI recommends ECDSA with a minimum key length of 256 bits.