Current File : //opt/alt/python35/lib/python3.5/site-packages/jwt/contrib/algorithms/py_ecdsa.py
# Note: This file is named py_ecdsa.py because import behavior in Python 2
# would cause ecdsa.py to squash the ecdsa library that it depends upon.
import hashlib
import ecdsa
from jwt.algorithms import Algorithm
from jwt.compat import string_types, text_type
class ECAlgorithm(Algorithm):
"""
Performs signing and verification operations using
ECDSA and the specified hash function
This class requires the ecdsa package to be installed.
This is based off of the implementation in PyJWT 0.3.2
"""
SHA256 = hashlib.sha256
SHA384 = hashlib.sha384
SHA512 = hashlib.sha512
def __init__(self, hash_alg):
self.hash_alg = hash_alg
def prepare_key(self, key):
if isinstance(key, ecdsa.SigningKey) or \
isinstance(key, ecdsa.VerifyingKey):
return key
if isinstance(key, string_types):
if isinstance(key, text_type):
key = key.encode('utf-8')
# Attempt to load key. We don't know if it's
# a Signing Key or a Verifying Key, so we try
# the Verifying Key first.
try:
key = ecdsa.VerifyingKey.from_pem(key)
except ecdsa.der.UnexpectedDER:
key = ecdsa.SigningKey.from_pem(key)
else:
raise TypeError('Expecting a PEM-formatted key.')
return key
def sign(self, msg, key):
return key.sign(msg, hashfunc=self.hash_alg,
sigencode=ecdsa.util.sigencode_string)
def verify(self, msg, key, sig):
try:
return key.verify(sig, msg, hashfunc=self.hash_alg,
sigdecode=ecdsa.util.sigdecode_string)
except AssertionError:
return False
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