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# Copyright (C) 2017 Jan Jancar
#
# This file is a part of the Mailman PGP plugin.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# this program. If not, see <http://www.gnu.org/licenses/>.
"""Miscellaneous PGP utilities."""
from pgpy import PGPKey, PGPSignature
from pgpy.constants import SignatureType
from pgpy.errors import PGPError
from pgpy.packet import Packet, Signature
from pgpy.types import Armorable
from public import public
@public
def verifies(verifications):
"""
:param verifications:
:type verifications: typing.Sequence[pgpy.types.SignatureVerification]
:return: bool
"""
return all(bool(verification) and
all(not sigsubj.signature.is_expired
for sigsubj in verification.good_signatures) for
verification in verifications)
@public
def hashes(verifications):
"""
:param verifications:
:return:
:rtype: typing.Generator[bytes]
"""
for verification in verifications:
for sigsubj in verification.good_signatures:
data = sigsubj.signature.hashdata(sigsubj.subject)
hasher = sigsubj.signature.hash_algorithm.hasher
hasher.update(data)
yield hasher.digest()
@public
def key_from_blob(blob):
"""
:param blob:
:return:
:rtype: pgpy.PGPKey
"""
key, _ = PGPKey.from_blob(blob)
return key
@public
def key_from_file(file):
"""
:param file:
:return:
:rtype: pgpy.PGPKey
"""
key, _ = PGPKey.from_file(file)
return key
@public
def revoc_from_blob(blob):
"""
Load a key revocation signature from an ASCII-Armored blob.
:param blob:
:return:
:rtype: pgpy.PGPSignature
"""
dearm = Armorable.ascii_unarmor(blob)
p = Packet(dearm['body'])
if not isinstance(p, Signature):
raise ValueError('Not a key revocation signature.')
if p.sigtype not in (SignatureType.KeyRevocation,
SignatureType.SubkeyRevocation):
raise ValueError('Not a key revocation.')
sig = PGPSignature()
sig |= p
return sig
@public
def key_flags(key):
if key.is_expired:
return set()
for revoc in key.revocation_signatures:
try:
verified = key.verify(key, revoc)
except PGPError:
continue
if bool(verified):
return set()
usage_flags = set()
uids = (uid for uid in key.userids if uid.is_primary)
uids = list(uids)
if len(uids) == 0:
uids = key.userids
for uid in uids:
revoked = False
for sig in uid.signatures:
if sig.type is not SignatureType.CertRevocation:
continue
if sig.signer == key.fingerprint.keyid:
try:
verified = key.verify(uid, sig)
except PGPError:
continue
if bool(verified):
revoked = True
if not revoked:
usage_flags |= uid.selfsig.key_flags
break
for subkey in key.subkeys.values():
if subkey.is_expired:
continue
valid = True
for revoc in subkey.revocation_signatures:
try:
verified = key.verify(subkey, revoc)
except PGPError:
continue
if bool(verified):
valid = False
break
if valid:
usage_flags |= subkey.usage_flags()
return usage_flags
@public
def key_usable(key, flags_required):
"""
Check that the `key` has the `flags_required` set of KeyFlags.
Checks only non-expired, non-revoked key/subkeys. Validates revocations it
can, so not those made with some other designated revocation key.
:param key: The key to check.
:type key: pgpy.PGPKey
:param flags_required: The set of flags required.
:type flags_required: set
:return: Whether the key has the flags_required.
:rtype: bool
"""
if key.is_expired:
return False
for revoc in key.revocation_signatures:
try:
verified = key.verify(key, revoc)
except PGPError:
continue
if bool(verified):
return False
return flags_required.issubset(key_flags(key))
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