In io.js or node >= 0.11 this module is just a shortcut to crypto.createECDH. In node <= 0.11 or the browser this is a pure JavaScript implimentation, more specifically a wrapper around elliptic, to give it the same API as node. secp256k1, secp224r1 (aka p224), prime256v1 (aka p256, secp256r1), prime192v1 (aka p192, secp192r1), secp384r1 (aka p384), secp521r1 (aka p521) curves all work in both this library and node (though only the highlighted name will work in node).