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45 lines
1.7 KiB
Python
45 lines
1.7 KiB
Python
"""Device abstraction layer for GPG operations."""
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import logging
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from .. import device, formats, util
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log = logging.getLogger(__name__)
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class HardwareSigner(object):
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"""Sign messages and get public keys from a hardware device."""
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def __init__(self, user_id, curve_name):
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"""Connect to the device and retrieve required public key."""
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self.device = device.detect(identity_str='',
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curve_name=curve_name)
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self.device.identity_dict['proto'] = 'gpg'
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self.device.identity_dict['host'] = user_id
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self.user_id = user_id
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def pubkey(self, ecdh=False):
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"""Return public key as VerifyingKey object."""
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with self.device:
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pubkey = self.device.pubkey(ecdh=ecdh)
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return formats.decompress_pubkey(
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pubkey=pubkey, curve_name=self.device.curve_name)
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def sign(self, digest):
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"""Sign the digest and return a serialized signature."""
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log.info('please confirm GPG signature on %s for "%s"...',
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self.device, self.user_id)
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if self.device.curve_name == formats.CURVE_NIST256:
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digest = digest[:32] # sign the first 256 bits
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log.debug('signing digest: %s', util.hexlify(digest))
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with self.device:
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sig = self.device.sign(blob=digest)
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return (util.bytes2num(sig[:32]), util.bytes2num(sig[32:]))
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def ecdh(self, pubkey):
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"""Derive shared secret using ECDH from remote public key."""
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log.info('please confirm GPG decryption on %s for "%s"...',
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self.device, self.user_id)
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with self.device:
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return self.device.ecdh(pubkey=pubkey)
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