def _verify_drkey_reply(self, rep, meta):
"""
Verify that the first order DRKey reply is legit.
I.e. the signature matches, timestamp is recent.
:param DRKeyReply rep: the first order DRKey reply.
:param UDPMetadata meta: the metadata.
:returns Certificate of the responder.
:rtype: Certificate
:raises: SCIONVerificationError
"""
if meta and meta.ia != rep.isd_as:
raise SCIONVerificationError("Response from other ISD-AS: %s" % rep.isd_as)
if drkey_time() - rep.p.timestamp > DRKEY_REQUEST_TIMEOUT:
raise SCIONVerificationError("Expired reply from %s. %ss old. Max %ss" % (
rep.isd_as, drkey_time() - rep.p.timestamp, DRKEY_REQUEST_TIMEOUT))
trc = self.trust_store.get_trc(rep.isd_as[0])
chain = self.trust_store.get_cert(rep.isd_as, rep.p.certVerSrc)
err = []
if not chain:
self._send_cc_request(rep.isd_as, rep.p.certVerSrc)
err.append("Certificate not present for %s(v: %s)" % (rep.isd_as, rep.p.certVerSrc))
if not trc:
self._send_trc_request(rep.isd_as[0], rep.p.trcVer, rep.isd_as[1])
err.append("TRC not present for %s(v: %s)" % (rep.isd_as[0], rep.p.trcVer))
if err:
raise SCIONVerificationError(", ".join(err))
raw = get_signing_input_rep(rep.isd_as, rep.p.timestamp, rep.p.expTime, rep.p.cipher)
try:
verify_sig_chain_trc(raw, rep.p.signature, rep.isd_as, chain, trc)
except SCIONVerificationError as e:
raise SCIONVerificationError(str(e))
return chain.certs[0]
def _verify_drkey_request(self, req, meta):
"""
Verify that the first order DRKey request is legit.
I.e. the signature is valid, the correct ISD AS is queried, timestamp is recent.
:param DRKeyRequest req: the first order DRKey request.
:param UDPMetadata meta: the metadata.
:returns Certificate of the requester.
:rtype: Certificate
:raises: SCIONVerificationError
"""
if self.addr.isd_as != req.isd_as:
raise SCIONVerificationError("Request for other ISD-AS: %s" % req.isd_as)
if drkey_time() - req.p.timestamp > DRKEY_REQUEST_TIMEOUT:
raise SCIONVerificationError("Expired request from %s. %ss old. Max %ss" % (
meta.ia, drkey_time() - req.p.timestamp, DRKEY_REQUEST_TIMEOUT))
trc = self.trust_store.get_trc(meta.ia[0])
chain = self.trust_store.get_cert(meta.ia, req.p.certVer)
err = []
if not chain:
self._send_cc_request(meta.ia, req.p.certVer)
err.append("Certificate not present for %s(v: %s)" % (meta.ia, req.p.certVer))
if not trc:
self._send_trc_request(meta.ia[0], req.p.trcVer, meta.ia[1])
err.append("TRC not present for %s(v: %s)" % (meta.ia[0], req.p.trcVer))
if err:
raise SCIONVerificationError(", ".join(err))
raw = drkey_signing_input_req(req.isd_as, req.p.flags.prefetch, req.p.timestamp)
try:
verify_sig_chain_trc(raw, req.p.signature, meta.ia, chain, trc)
except SCIONVerificationError as e:
raise SCIONVerificationError(str(e))
return chain.certs[0]
def get_drkey_reply(sv, src_ia, dst_ia, priv_key, signing_key, cert_ver,
dst_cert, trc_ver):
"""
Generate a DRKeyReply. The Reply is signed with the signing key.
The contained drkey is encrypted using the public key of the
destination certificate.
:param DRKeySecretValue sv: the local secret value used to derive the DRKey.
:param ISD_AS src_ia: the local ISD-AS address.
:param ISD_AS dst_ia: the ISD-AS for which the DRKey is computed.
:param PrivateKey priv_key: local private key.
:param SigningKey signing_key: local signing key.
:param int cert_ver: version of the certificate, priv_key and signing_key are associated with.
:param Certificate dst_cert: the certificated of the destination ISD-AS.
:param int trc_ver: version of trc associated with cert_ver.
:returns: the resulting DRKeyReply
:rtype: DRKeyReply
"""
drkey = derive_drkey_raw(sv, dst_ia)
cipher = bytes(
encrypt(drkey, priv_key, PublicKey(dst_cert.subject_enc_key_raw)))
timestamp = drkey_time()
signature = sign(
get_signing_input_rep(src_ia, timestamp, sv.exp_time, cipher),
signing_key)
return DRKeyReply.from_values(src_ia, timestamp, sv.exp_time, cipher,
signature, cert_ver, dst_cert.version,
trc_ver)
def get_drkey_request(dst_ia, prefetch, signing_key, cert_ver, trc_ver):
"""
Generate a DRKeyRequest. The Request is signed with the signing key of the
specified certificate.
:param ISD_AS dst_ia: destination of the DRKey request.
:param Bool prefetch: indicator if prefetch (True) or not (False).
:param SigningKey signing_key: the signing key
:param int cert_ver: version of the certificate associated with singing key
:param int trc_ver: version of the trc associated with the certificate.
:returns: the signed DRKeyRequest.
:rtype: DRKeyRequest
"""
timestamp = drkey_time()
signature = sign(drkey_signing_input_req(dst_ia, prefetch, timestamp),
signing_key)
return DRKeyRequest.from_values(prefetch, dst_ia, timestamp, signature,
cert_ver, trc_ver)
