Elliptic Curve DSA
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Elliptic Curve DSA (ECDSA) is a variant of the Digital Signature Algorithm (DSA) which operates on elliptic curve groups.
Superior efficiency is one reason this algorithm is preferred over DSA. DSA requires that <math>p>2^{512}<math> in order to be secure against a number field sieve attack and <math>q>2^{160}<math> in order to be secure against a baby-step giant-step attack. In practical terms, this means the DSA is slower than RSA as a signature scheme.
However elliptic curve groups are not vulnerable to a number field sieve attack, so they can be securely implemented with smaller key sizes and can be faster than RSA.