6 from Crypto.PublicKey import RSA
7 from Crypto.Hash import SHA, SHA256, SHA512
8 from Crypto.Signature import PKCS1_v1_5
10 from .remote_actor import fetch_actor
20 def split_signature(sig):
21 default = {"headers": "date"}
23 sig = sig.strip().split(',')
26 k, _, v = chunk.partition('=')
30 default['headers'] = default['headers'].split()
34 def build_signing_string(headers, used_headers):
35 return '\n'.join(map(lambda x: ': '.join([x.lower(), headers[x]]), used_headers))
38 def sign_headers(headers, key, key_id):
39 headers = {x.lower(): y for x, y in headers.items()}
40 used_headers = headers.keys()
43 'algorithm': 'rsa-sha256',
44 'headers': ' '.join(used_headers)
46 sigstring = build_signing_string(headers, used_headers)
48 pkcs = PKCS1_v1_5.new(key)
50 h.update(sigstring.encode('ascii'))
51 sigdata = pkcs.sign(h)
53 sigdata = base64.b64encode(sigdata)
54 sig['signature'] = sigdata.decode('ascii')
56 chunks = ['{}="{}"'.format(k, v) for k, v in sig.items()]
57 return ','.join(chunks)
60 async def fetch_actor_key(actor):
61 actor_data = await fetch_actor(actor)
66 if 'publicKey' not in actor_data:
69 if 'publicKeyPem' not in actor_data['publicKey']:
72 return RSA.importKey(actor_data['publicKey']['publicKeyPem'])
75 async def validate(actor, request):
76 pubkey = await fetch_actor_key(actor)
80 logging.debug('actor key: %r', pubkey)
82 headers = request.headers.copy()
83 headers['(request-target)'] = ' '.join([request.method.lower(), request.path])
85 sig = split_signature(headers['signature'])
86 logging.debug('sigdata: %r', sig)
88 sigstring = build_signing_string(headers, sig['headers'])
89 logging.debug('sigstring: %r', sigstring)
91 sign_alg, _, hash_alg = sig['algorithm'].partition('-')
92 logging.debug('sign alg: %r, hash alg: %r', sign_alg, hash_alg)
94 sigdata = base64.b64decode(sig['signature'])
96 pkcs = PKCS1_v1_5.new(pubkey)
97 h = HASHES[hash_alg].new()
98 h.update(sigstring.encode('ascii'))
99 result = pkcs.verify(h, sigdata)
101 request['validated'] = result
103 logging.debug('validates? %r', result)
107 async def http_signatures_middleware(app, handler):
108 async def http_signatures_handler(request):
109 request['validated'] = False
111 if 'signature' in request.headers:
112 data = await request.json()
113 if 'actor' not in data:
114 raise aiohttp.web.HTTPUnauthorized(body='signature check failed, no actor in message')
116 actor = data["actor"]
117 if not (await validate(actor, request)):
118 logging.info('Signature validation failed for: %r', actor)
119 raise aiohttp.web.HTTPUnauthorized(body='signature check failed, signature did not match key')
121 return (await handler(request))
123 return (await handler(request))
125 return http_signatures_handler