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import base64
import binascii
import struct
from .compat import binary_type, bytes_from_int, text_type
try:
from cryptography.hazmat.primitives.asymmetric.utils import (
decode_dss_signature, encode_dss_signature
)
except ImportError:
pass
def force_unicode(value):
if isinstance(value, binary_type):
return value.decode('utf-8')
elif isinstance(value, text_type):
return value
else:
raise TypeError('Expected a string value')
def force_bytes(value):
if isinstance(value, text_type):
return value.encode('utf-8')
elif isinstance(value, binary_type):
return value
else:
raise TypeError('Expected a string value')
def base64url_decode(input):
if isinstance(input, text_type):
input = input.encode('ascii')
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 to_base64url_uint(val):
if val < 0:
raise ValueError('Must be a positive integer')
int_bytes = bytes_from_int(val)
if len(int_bytes) == 0:
int_bytes = b'\x00'
return base64url_encode(int_bytes)
def from_base64url_uint(val):
if isinstance(val, text_type):
val = val.encode('ascii')
data = base64url_decode(val)
buf = struct.unpack('%sB' % len(data), data)
return int(''.join(["%02x" % byte for byte in buf]), 16)
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_dss_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_dss_signature(r, s)
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