52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
# -*- coding: utf-8 -*-
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import warnings
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import os
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from collections import namedtuple
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from . import djbec
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__all__ = ['crypto_sign', 'crypto_sign_open', 'crypto_sign_keypair', 'Keypair',
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'PUBLICKEYBYTES', 'SECRETKEYBYTES', 'SIGNATUREBYTES']
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PUBLICKEYBYTES=32
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SECRETKEYBYTES=64
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SIGNATUREBYTES=64
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Keypair = namedtuple('Keypair', ('vk', 'sk')) # verifying key, secret key
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def crypto_sign_keypair(seed=None):
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"""Return (verifying, secret) key from a given seed, or os.urandom(32)"""
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if seed is None:
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seed = os.urandom(PUBLICKEYBYTES)
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else:
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warnings.warn("ed25519ll should choose random seed.",
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RuntimeWarning)
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if len(seed) != 32:
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raise ValueError("seed must be 32 random bytes or None.")
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skbytes = seed
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vkbytes = djbec.publickey(skbytes)
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return Keypair(vkbytes, skbytes+vkbytes)
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def crypto_sign(msg, sk):
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"""Return signature+message given message and secret key.
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The signature is the first SIGNATUREBYTES bytes of the return value.
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A copy of msg is in the remainder."""
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if len(sk) != SECRETKEYBYTES:
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raise ValueError("Bad signing key length %d" % len(sk))
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vkbytes = sk[PUBLICKEYBYTES:]
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skbytes = sk[:PUBLICKEYBYTES]
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sig = djbec.signature(msg, skbytes, vkbytes)
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return sig + msg
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def crypto_sign_open(signed, vk):
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"""Return message given signature+message and the verifying key."""
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if len(vk) != PUBLICKEYBYTES:
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raise ValueError("Bad verifying key length %d" % len(vk))
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rc = djbec.checkvalid(signed[:SIGNATUREBYTES], signed[SIGNATUREBYTES:], vk)
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if not rc:
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raise ValueError("rc != True", rc)
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return signed[SIGNATUREBYTES:]
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