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formats: split serialization from decompression

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This commit is contained in:
Roman Zeyde 2015-07-22 13:47:53 +03:00
parent 38136e76d5
commit 2ce448f736
1 changed files with 10 additions and 6 deletions
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16
sshagent/formats.py
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@ -9,7 +9,7 @@ import logging
log = logging.getLogger(__name__)
DER_OCTET_STRING = b'\x04'
ECDSA_KEY_TYPE = b'ecdsa-sha2-nistp256'
ECDSA_KEY_PREFIX = b'ecdsa-sha2-'
ECDSA_CURVE_NAME = b'nistp256'
hashfunc = hashlib.sha256
@ -61,15 +61,19 @@ def decompress_pubkey(pub, curve=ecdsa.NIST256p):
y = (P-beta) if ((beta + p0) % 2) else beta
point = ecdsa.ellipticcurve.Point(curve.curve, x, y)
vk = ecdsa.VerifyingKey.from_public_point(point, curve=curve,
hashfunc=hashfunc)
parts = [ECDSA_KEY_TYPE, ECDSA_CURVE_NAME,
DER_OCTET_STRING + vk.to_string()]
return ecdsa.VerifyingKey.from_public_point(point, curve=curve,
hashfunc=hashfunc)
def serialize_verifying_key(vk):
key_type = ECDSA_KEY_PREFIX + ECDSA_CURVE_NAME
curve_name = ECDSA_CURVE_NAME
key_blob = DER_OCTET_STRING + vk.to_string()
parts = [key_type, curve_name, key_blob]
return b''.join([util.frame(p) for p in parts])
def export_public_key(pubkey, label):
blob = decompress_pubkey(pubkey)
blob = serialize_verifying_key(decompress_pubkey(pubkey))
log.debug('fingerprint: %s', fingerprint(blob))
b64 = base64.b64encode(blob).decode('ascii')
return '{} {} {}\n'.format(ECDSA_KEY_TYPE.decode('ascii'), b64, label)