session_keys (rubygems):     SessionKeys is a cryptographic tool for the deterministic generation of     NaCl compatible Curve25519 encryption and Ed25519 digital signature keys.      The strength of the system is rooted in the fact that the keypairs are derived from     passing an identifier, such as a username or email address, and a high-entropy     passphrase through the SHA256 one-way hash and the scrypt key derivation     functions. This means that no private key material need ever be writter to     disk or transmitted. The generated keys are deterministic; for any given ID,     password, and strength combination the same keys will always be returned. 
Keywords: crypto|cryptographic|cryptography|curve25519|digital-signature|ed25519|encryption|encryption-key|keypair|signing|signing-keys|strength|tweetnacl