bookwyrm/fedireads/signatures.py

83 lines
2.7 KiB
Python
Raw Normal View History

from urllib.parse import urlparse
from base64 import b64encode, b64decode
from Crypto import Random
from Crypto.PublicKey import RSA
from Crypto.Signature import pkcs1_15 #pylint: disable=no-name-in-module
from Crypto.Hash import SHA256
def create_key_pair():
random_generator = Random.new().read
key = RSA.generate(1024, random_generator)
private_key = key.export_key().decode('utf8')
public_key = key.publickey().export_key().decode('utf8')
return private_key, public_key
def make_signature(sender, destination, date):
inbox_parts = urlparse(destination)
signature_headers = [
'(request-target): post %s' % inbox_parts.path,
'host: %s' % inbox_parts.netloc,
'date: %s' % date,
]
message_to_sign = '\n'.join(signature_headers)
signer = pkcs1_15.new(RSA.import_key(sender.private_key))
signed_message = signer.sign(SHA256.new(message_to_sign.encode('utf8')))
signature = {
'keyId': '%s#main-key' % sender.remote_id,
'algorithm': 'rsa-sha256',
'headers': '(request-target) host date',
'signature': b64encode(signed_message).decode('utf8'),
}
return ','.join('%s="%s"' % (k, v) for (k, v) in signature.items())
class Signature:
def __init__(self, key_id, headers, signature):
self.key_id = key_id
self.headers = headers
self.signature = signature
@classmethod
def parse(cls, request):
signature_dict = {}
for pair in request.headers['Signature'].split(','):
k, v = pair.split('=', 1)
v = v.replace('"', '')
signature_dict[k] = v
try:
key_id = signature_dict['keyId']
headers = signature_dict['headers']
signature = b64decode(signature_dict['signature'])
except KeyError:
raise ValueError('Invalid auth header')
return cls(key_id, headers, signature)
def verify(self, public_key, request):
''' verify rsa signature '''
public_key = RSA.import_key(public_key)
comparison_string = []
for signed_header_name in self.headers.split(' '):
if signed_header_name == '(request-target)':
comparison_string.append(
'(request-target): post %s' % request.path)
else:
comparison_string.append('%s: %s' % (
signed_header_name,
request.headers[signed_header_name]
))
comparison_string = '\n'.join(comparison_string)
signer = pkcs1_15.new(public_key)
digest = SHA256.new()
digest.update(comparison_string.encode())
# raises a ValueError if it fails
signer.verify(digest, self.signature)