Source code for spiral.keys

import fcntl
import os
import struct

from nacl.public import PrivateKey
from zope.interface import implementer, Attribute, Interface

counterStruct = struct.Struct('<Q')

[docs]class IKeyAndNonceScheme(Interface): """ A key and nonce generation scheme. """ key = Attribute('A nacl.public.PrivateKey instance.')
[docs] def nonce(longterm=False): """ Generate a nonce. :param longterm: True to increment the long-term counter; False to increment the short-term counter. :returns: 16 bytes. """
[docs]class Keydir(object): """ A key loaded from disk, probably generated by ``curvecpmakekey``. Nonces are eight random bytes concatenated to a counter persisted to disk. :param keydir: The path to a key directory. """ def __init__(self, keydir): self.keydir = keydir with open(self.expertsFile('secretkey')) as infile: self.key = PrivateKey( def expertsFile(self, name): return os.path.join(self.keydir, '.expertsonly', name) def nonce(self, longterm=False): with open(self.expertsFile('lock'), 'r+') as lockfile: fcntl.lockf(lockfile, fcntl.LOCK_EX) with open(self.expertsFile('noncecounter'), 'rb+') as noncefile: data = counter, = counterStruct.unpack(data) counter += 1048576 if longterm else 1 data = counterStruct.pack(counter) noncefile.write(data) return os.urandom(8) + data
[docs]class EphemeralKey(object): """ An unpersisted, randomly-generated key. Nonces are 16 random bytes. """ def __init__(self): self.key = PrivateKey.generate() def nonce(self, longterm=False): return os.urandom(16)