BitAuth is a way to do secure, passwordless authentication using the cryptography in Bitcoin. Instead of using a shared secret, the client signs each request using a private key and the server checks to make sure the signature is valid and matches the public key.BitAuth uses the same technology in Bitcoin. A public private key pair is created using elliptic curve secp256k1. The public SIN (System identification number), like a bitcoin address, is the RIPEMD 160, SHA256 hash of the public key. See https://en.bitcoin.it/wiki/Identity_protocol_v1 for complete details.