kopia lustrzana https://gitlab.com/marnanel/chapeau
79 wiersze
1.9 KiB
Python
79 wiersze
1.9 KiB
Python
# crypto.py
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#
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# Part of kepi, an ActivityPub daemon.
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# Copyright (c) 2018-2019 Marnanel Thurman.
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# Licensed under the GNU Public License v2.
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"""
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Various crypto routines, used for signing messages and
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verifying other people's signatures.
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"""
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from Crypto.PublicKey import RSA
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from Crypto.Hash import SHA256
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from struct import pack
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import base64
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import hashlib
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def base64url_encode(data):
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"""
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base64-encodes its input, using the modified URL-safe
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alphabet given in RFC 4648.
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"""
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b = base64.b64encode(s=data,
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altchars=b'-_')
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return str(b, encoding='ASCII')
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def bignum_to_bytes(bignum):
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temp = bignum
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result = []
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while temp!=0:
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result.append(temp & 0xFF)
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temp >>= 8
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result.reverse()
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return bytes(result)
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class Key(object):
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"""
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An RSA public/private key pair, which can produce
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a magic-envelope signature for itself.
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I was going to subclass the RSA key object,
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but it's hidden away and has an underscore prefix,
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so I guess the developers thought that was a bad idea.
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So I'm wrapping it, instead.
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"""
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def __init__(self):
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self._rsa_key = RSA.generate(1024)
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def private_as_pem(self):
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return str(self._rsa_key.exportKey('PEM'),
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encoding='ASCII')
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def public_as_pem(self):
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return str(self._rsa_key.publickey().exportKey('PEM'),
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encoding='ASCII')
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def modulus(self):
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return self._rsa_key.n
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def public_exponent(self):
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return self._rsa_key.e
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def private_exponent(self):
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return self._rsa_key.d
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def magic_envelope(self):
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return 'RSA.{0}.{1}'.format(
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base64url_encode(
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bignum_to_bytes(
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self._rsa_key.n)),
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base64url_encode(
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bignum_to_bytes(
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self._rsa_key.e)),
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)
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