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Fix bugs in generating event signatures and hashing

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This commit is contained in:
Erik Johnston 2014-11-03 17:51:42 +00:00
parent bab2846513
commit 68698e0ac8
6 changed files with 58 additions and 96 deletions
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116
synapse/crypto/event_signing.py
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@ -15,11 +15,11 @@
# limitations under the License.
from synapse.federation.units import Pdu
from synapse.api.events.utils import prune_pdu, prune_event
from synapse.api.events.utils import prune_event
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
from syutil.crypto.jsonsign import sign_json
from synapse.api.events.room import GenericEvent
import copy
import hashlib
@ -28,20 +28,14 @@ import logging
logger = logging.getLogger(__name__)
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):
def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
"""Check whether the hash for this PDU matches the contents"""
computed_hash = _compute_content_hash(pdu, hash_algorithm)
if computed_hash.name not in pdu.hashes:
computed_hash = _compute_content_hash(event, hash_algorithm)
if computed_hash.name not in event.hashes:
raise Exception("Algorithm %s not in hashes %s" % (
computed_hash.name, list(pdu.hashes)
computed_hash.name, list(event.hashes)
))
message_hash_base64 = pdu.hashes[computed_hash.name]
message_hash_base64 = event.hashes[computed_hash.name]
try:
message_hash_bytes = decode_base64(message_hash_base64)
except:
@ -49,62 +43,7 @@ def check_event_pdu_content_hash(pdu, hash_algorithm=hashlib.sha256):
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", None)
pdu_json.pop("unsigned", None)
pdu_json.pop("signatures", None)
pdu_json.pop("hashes", None)
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.pop("signatures", None)
pdu_json_bytes = encode_canonical_json(pdu_json)
hashed = hash_algorithm(pdu_json_bytes)
return (hashed.name, hashed.digest())
def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
tmp_event = copy.deepcopy(event)
tmp_event = prune_event(tmp_event)
event_json = tmp_event.get_dict()
event_json.pop("signatures", None)
event_json_bytes = encode_canonical_json(event_json)
hashed = hash_algorithm(event_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_json = 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)
def add_hashes_and_signatures(event, signature_name, signing_key,
hash_algorithm=hashlib.sha256):
tmp_event = copy.deepcopy(event)
tmp_event = prune_event(tmp_event)
redact_json = tmp_event.get_dict()
redact_json.pop("signatures", None)
redact_json = sign_json(redact_json, signature_name, signing_key)
event.signatures = redact_json["signatures"]
def _compute_content_hash(event, hash_algorithm):
event_json = event.get_full_dict()
#TODO: We need to sign the JSON that is going out via fedaration.
event_json.pop("age_ts", None)
@ -112,7 +51,44 @@ def add_hashes_and_signatures(event, signature_name, signing_key,
event_json.pop("signatures", None)
event_json.pop("hashes", None)
event_json_bytes = encode_canonical_json(event_json)
return hash_algorithm(event_json_bytes)
def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
# FIXME(erikj): GenericEvent!
tmp_event = GenericEvent(**event.get_full_dict())
tmp_event = prune_event(tmp_event)
event_json = tmp_event.get_dict()
event_json.pop("signatures", None)
event_json.pop("age_ts", None)
event_json.pop("unsigned", None)
event_json_bytes = encode_canonical_json(event_json)
hashed = hash_algorithm(event_json_bytes)
return (hashed.name, hashed.digest())
def compute_event_signature(event, signature_name, signing_key):
tmp_event = copy.deepcopy(event)
tmp_event = prune_event(tmp_event)
redact_json = tmp_event.get_full_dict()
redact_json.pop("signatures", None)
redact_json.pop("age_ts", None)
redact_json.pop("unsigned", None)
logger.debug("Signing event: %s", redact_json)
redact_json = sign_json(redact_json, signature_name, signing_key)
return redact_json["signatures"]
def add_hashes_and_signatures(event, signature_name, signing_key,
hash_algorithm=hashlib.sha256):
hashed = _compute_content_hash(event, hash_algorithm=hash_algorithm)
if not hasattr(event, "hashes"):
event.hashes = {}
event.hashes[hashed.name] = encode_base64(hashed.digest())
event.signatures = compute_event_signature(
event,
signature_name=signature_name,
signing_key=signing_key,
)