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# -*- coding: utf-8 -*-
# Copyright 2014 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from synapse.federation.units import Pdu
from synapse.api.events.utils import prune_pdu
from syutil.jsonutil import encode_canonical_json
from syutil.base64util import encode_base64, decode_base64
from syutil.crypto.jsonsign import sign_json, verify_signed_json
import hashlib
def add_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
hashed = _compute_content_hash(pdu, hash_algorithm)
pdu.hashes[hashed.name] = encode_base64(hashed.digest())
return pdu
def check_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
"""Check whether the hash for this PDU matches the contents"""
computed_hash = _compute_content_hash(pdu, hash_algortithm)
if computed_hash.name not in pdu.hashes:
raise Exception("Algorithm %s not in hashes %s" % (
computed_hash.name, list(pdu.hashes)
))
message_hash_base64 = hashes[computed_hash.name]
try:
message_hash_bytes = decode_base64(message_hash_base64)
except:
raise Exception("Invalid base64: %s" % (message_hash_base64,))
return message_hash_bytes == computed_hash.digest()
def _compute_content_hash(pdu, hash_algorithm):
pdu_json = pdu.get_dict()
#TODO: Make "age_ts" key internal
pdu_json.pop("age_ts")
pdu_json.pop("unsigned", None)
pdu_json.pop("signatures", None)
hashes = pdu_json.pop("hashes", {})
pdu_json_bytes = encode_canonical_json(pdu_json)
return hash_algorithm(pdu_json_bytes)
def compute_pdu_event_reference_hash(pdu, hash_algorithm=hashlib.sha256):
tmp_pdu = Pdu(**pdu.get_dict())
tmp_pdu = prune_pdu(tmp_pdu)
pdu_json = tmp_pdu.get_dict()
pdu_json_bytes = encode_canonical_json(pdu_json)
hashed = hash_algorithm(pdu_json_bytes)
return (hashed.name, hashed.digest())
def sign_event_pdu(pdu, signature_name, signing_key):
tmp_pdu = Pdu(**pdu.get_dict())
tmp_pdu = prune_pdu(tmp_pdu)
pdu_json = tmp_pdu.get_dict()
pdu_jdon = sign_json(pdu_json, signature_name, signing_key)
pdu.signatures = pdu_json["signatures"]
return pdu
def verify_signed_event_pdu(pdu, signature_name, verify_key):
tmp_pdu = Pdu(**pdu.get_dict())
tmp_pdu = prune_pdu(tmp_pdu)
pdu_json = tmp_pdu.get_dict()
verify_signed_json(pdu_json, signature_name, verify_key)
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