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63 lines
2.0 KiB
Python
63 lines
2.0 KiB
Python
"""
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Connection to hardware authentication device.
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It is used for getting SSH public keys and ECDSA signing of server requests.
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"""
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import io
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import logging
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from . import formats, util
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log = logging.getLogger(__name__)
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class Client(object):
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"""Client wrapper for SSH authentication device."""
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def __init__(self, device):
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"""Connect to hardware device."""
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device.identity_dict['proto'] = 'ssh'
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self.device = device
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def get_public_key(self):
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"""Get SSH public key from the device."""
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with self.device:
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pubkey = self.device.pubkey()
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vk = formats.decompress_pubkey(pubkey=pubkey,
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curve_name=self.device.curve_name)
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return formats.export_public_key(vk=vk,
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label=self.device.identity_str())
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def sign_ssh_challenge(self, blob):
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"""Sign given blob using a private key on the device."""
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msg = _parse_ssh_blob(blob)
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log.debug('%s: user %r via %r (%r)',
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msg['conn'], msg['user'], msg['auth'], msg['key_type'])
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log.debug('nonce: %r', msg['nonce'])
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log.debug('fingerprint: %s', msg['public_key']['fingerprint'])
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log.debug('hidden challenge size: %d bytes', len(blob))
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log.info('please confirm user "%s" login to "%s" using %s...',
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msg['user'].decode('ascii'), self.device.identity_str(),
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self.device)
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with self.device:
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return self.device.sign(blob=blob)
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def _parse_ssh_blob(data):
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res = {}
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i = io.BytesIO(data)
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res['nonce'] = util.read_frame(i)
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i.read(1) # SSH2_MSG_USERAUTH_REQUEST == 50 (from ssh2.h, line 108)
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res['user'] = util.read_frame(i)
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res['conn'] = util.read_frame(i)
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res['auth'] = util.read_frame(i)
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i.read(1) # have_sig == 1 (from sshconnect2.c, line 1056)
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res['key_type'] = util.read_frame(i)
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public_key = util.read_frame(i)
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res['public_key'] = formats.parse_pubkey(public_key)
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assert not i.read()
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return res
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