Viewing file:  utils.py (1.53 KB) -rw-r--r--
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import base64
import binascii
try:
from cryptography.hazmat.primitives.asymmetric.utils import (
decode_rfc6979_signature, encode_rfc6979_signature
)
except ImportError:
pass
def base64url_decode(input):
rem = len(input) % 4
if rem > 0:
input += b'=' * (4 - rem)
return base64.urlsafe_b64decode(input)
def base64url_encode(input):
return base64.urlsafe_b64encode(input).replace(b'=', b'')
def merge_dict(original, updates):
if not updates:
return original
try:
merged_options = original.copy()
merged_options.update(updates)
except (AttributeError, ValueError) as e:
raise TypeError('original and updates must be a dictionary: %s' % e)
return merged_options
def number_to_bytes(num, num_bytes):
padded_hex = '%0*x' % (2 * num_bytes, num)
big_endian = binascii.a2b_hex(padded_hex.encode('ascii'))
return big_endian
def bytes_to_number(string):
return int(binascii.b2a_hex(string), 16)
def der_to_raw_signature(der_sig, curve):
num_bits = curve.key_size
num_bytes = (num_bits + 7) // 8
r, s = decode_rfc6979_signature(der_sig)
return number_to_bytes(r, num_bytes) + number_to_bytes(s, num_bytes)
def raw_to_der_signature(raw_sig, curve):
num_bits = curve.key_size
num_bytes = (num_bits + 7) // 8
if len(raw_sig) != 2 * num_bytes:
raise ValueError('Invalid signature')
r = bytes_to_number(raw_sig[:num_bytes])
s = bytes_to_number(raw_sig[num_bytes:])
return encode_rfc6979_signature(r, s)
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