119 lines
3.1 KiB
Python
119 lines
3.1 KiB
Python
import aiohttp
|
|
import aiohttp.web
|
|
import base64
|
|
import logging
|
|
|
|
from Crypto.PublicKey import RSA
|
|
from Crypto.Hash import SHA, SHA256, SHA512
|
|
from Crypto.Signature import PKCS1_v1_5
|
|
|
|
from .remote_actor import fetch_actor
|
|
|
|
|
|
HASHES = {
|
|
'sha1': SHA,
|
|
'sha256': SHA256,
|
|
'sha512': SHA512
|
|
}
|
|
|
|
|
|
def split_signature(sig):
|
|
default = {"headers": "date"}
|
|
|
|
sig = sig.strip().split(',')
|
|
|
|
for chunk in sig:
|
|
k, _, v = chunk.partition('=')
|
|
v = v.strip('\"')
|
|
default[k] = v
|
|
|
|
default['headers'] = default['headers'].split()
|
|
return default
|
|
|
|
|
|
def build_signing_string(headers, used_headers):
|
|
return '\n'.join(map(lambda x: ': '.join([x.lower(), headers[x]]), used_headers))
|
|
|
|
|
|
def sign_headers(headers, key, key_id):
|
|
headers = {x.lower(): y for x, y in headers.items()}
|
|
used_headers = headers.keys()
|
|
sig = {
|
|
'keyId': key_id,
|
|
'algorithm': 'rsa-sha256',
|
|
'headers': ' '.join(used_headers)
|
|
}
|
|
sigstring = build_signing_string(headers, used_headers)
|
|
|
|
pkcs = PKCS1_v1_5.new(key)
|
|
h = SHA256.new()
|
|
h.update(sigstring.encode('ascii'))
|
|
sigdata = pkcs.sign(h)
|
|
|
|
sigdata = base64.b64encode(sigdata)
|
|
sig['signature'] = sigdata.decode('ascii')
|
|
|
|
chunks = ['{}="{}"'.format(k, v) for k, v in sig.items()]
|
|
return ','.join(chunks)
|
|
|
|
|
|
async def fetch_actor_key(actor):
|
|
actor_data = await fetch_actor(actor)
|
|
|
|
if 'publicKey' not in actor_data:
|
|
return None
|
|
|
|
if 'publicKeyPem' not in actor_data['publicKey']:
|
|
return None
|
|
|
|
return RSA.importKey(actor_data['publicKey']['publicKeyPem'])
|
|
|
|
|
|
async def validate(actor, request):
|
|
pubkey = await fetch_actor_key(actor)
|
|
logging.debug('actor key: %r', pubkey)
|
|
|
|
headers = request.headers.copy()
|
|
headers['(request-target)'] = ' '.join([request.method.lower(), request.path])
|
|
|
|
sig = split_signature(headers['signature'])
|
|
logging.debug('sigdata: %r', sig)
|
|
|
|
sigstring = build_signing_string(headers, sig['headers'])
|
|
logging.debug('sigstring: %r', sigstring)
|
|
|
|
sign_alg, _, hash_alg = sig['algorithm'].partition('-')
|
|
logging.debug('sign alg: %r, hash alg: %r', sign_alg, hash_alg)
|
|
|
|
sigdata = base64.b64decode(sig['signature'])
|
|
|
|
pkcs = PKCS1_v1_5.new(pubkey)
|
|
h = HASHES[hash_alg].new()
|
|
h.update(sigstring.encode('ascii'))
|
|
result = pkcs.verify(h, sigdata)
|
|
|
|
request['validated'] = result
|
|
|
|
logging.debug('validates? %r', result)
|
|
return result
|
|
|
|
|
|
async def http_signatures_middleware(app, handler):
|
|
async def http_signatures_handler(request):
|
|
request['validated'] = False
|
|
|
|
if 'signature' in request.headers:
|
|
data = await request.json()
|
|
if 'actor' not in data:
|
|
raise aiohttp.web.HTTPUnauthorized(body='signature check failed, no actor in message')
|
|
|
|
actor = data["actor"]
|
|
if not (await validate(actor, request)):
|
|
raise aiohttp.web.HTTPUnauthorized(body='signature check failed, signature did not match key')
|
|
|
|
return (await handler(request))
|
|
|
|
return (await handler(request))
|
|
|
|
return http_signatures_handler
|