This is an easy-to-use implementation of ECDSA cryptography (Elliptic Curve Digital Signature Algorithm), implemented purely in Python, released under the MIT license. With this library, you can quickly create keypairs (signing key and verifying key), sign messages, and verify the signatures. The keys and signatures are very short, making them easy to handle and incorporate into other protocols. This library provides key generation, signing, and verifying, for five popular NIST "Suite B" GF(p) curves, with key lengths of 192, 224, 256, 384, and 521 bits. The "short names" for these curves, as known by the OpenSSL tool (openssl ecparam -list_curves), are: prime192v1, secp224r1, prime256v1, secp384r1, and secp521r1. It also includes the 256-bit curve used by Bitcoin, whose short name is secp256k1. No other curves are included, but it would not be too hard to add more.