mirror of https://github.com/borgbackup/borg.git
1023 lines
38 KiB
Python
1023 lines
38 KiB
Python
import configparser
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import hmac
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import os
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import textwrap
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from binascii import a2b_base64, b2a_base64, hexlify
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from hashlib import sha256, pbkdf2_hmac
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from typing import Literal
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from ..logger import create_logger
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logger = create_logger()
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import argon2.low_level
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from ..constants import * # NOQA
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from ..compress import Compressor
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from ..helpers import StableDict
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from ..helpers import Error, IntegrityError
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from ..helpers import get_keys_dir, get_security_dir
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from ..helpers import get_limited_unpacker
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from ..helpers import bin_to_hex
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from ..helpers.passphrase import Passphrase, PasswordRetriesExceeded, PassphraseWrong
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from ..helpers import msgpack
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from ..helpers.manifest import Manifest
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from ..item import Key, EncryptedKey, want_bytes
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from ..platform import SaveFile
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from .nonces import NonceManager
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from .low_level import AES, bytes_to_long, long_to_bytes, bytes_to_int, num_cipher_blocks, hmac_sha256, blake2b_256, hkdf_hmac_sha512
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from .low_level import AES256_CTR_HMAC_SHA256, AES256_CTR_BLAKE2b, AES256_OCB, CHACHA20_POLY1305
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from . import low_level
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class UnsupportedPayloadError(Error):
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"""Unsupported payload type {}. A newer version is required to access this repository."""
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class UnsupportedManifestError(Error):
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"""Unsupported manifest envelope. A newer version is required to access this repository."""
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class KeyfileNotFoundError(Error):
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"""No key file for repository {} found in {}."""
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class KeyfileInvalidError(Error):
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"""Invalid key file for repository {} found in {}."""
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class KeyfileMismatchError(Error):
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"""Mismatch between repository {} and key file {}."""
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class RepoKeyNotFoundError(Error):
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"""No key entry found in the config of repository {}."""
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class UnsupportedKeyFormatError(Error):
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"""Your borg key is stored in an unsupported format. Try using a newer version of borg."""
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class TAMRequiredError(IntegrityError):
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__doc__ = textwrap.dedent("""
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Manifest is unauthenticated, but it is required for this repository. Is somebody attacking you?
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""").strip()
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traceback = False
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class TAMInvalid(IntegrityError):
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__doc__ = IntegrityError.__doc__
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traceback = False
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def __init__(self):
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# Error message becomes: "Data integrity error: Manifest authentication did not verify"
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super().__init__('Manifest authentication did not verify')
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class TAMUnsupportedSuiteError(IntegrityError):
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"""Could not verify manifest: Unsupported suite {!r}; a newer version is needed."""
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traceback = False
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def key_creator(repository, args, *, other_key=None):
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for key in AVAILABLE_KEY_TYPES:
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if key.ARG_NAME == args.encryption:
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assert key.ARG_NAME is not None
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return key.create(repository, args, other_key=other_key)
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else:
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raise ValueError('Invalid encryption mode "%s"' % args.encryption)
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def key_argument_names():
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return [key.ARG_NAME for key in AVAILABLE_KEY_TYPES if key.ARG_NAME]
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def identify_key(manifest_data):
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key_type = manifest_data[0]
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if key_type == KeyType.PASSPHRASE: # legacy, see comment in KeyType class.
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return RepoKey
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for key in AVAILABLE_KEY_TYPES:
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if key.TYPE == key_type:
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return key
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else:
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raise UnsupportedPayloadError(key_type)
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def key_factory(repository, manifest_data):
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return identify_key(manifest_data).detect(repository, manifest_data)
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def tam_required_file(repository):
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security_dir = get_security_dir(bin_to_hex(repository.id))
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return os.path.join(security_dir, 'tam_required')
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def tam_required(repository):
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file = tam_required_file(repository)
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return os.path.isfile(file)
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def uses_same_id_hash(other_key, key):
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"""other_key -> key upgrade: is the id hash the same?"""
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# avoid breaking the deduplication by changing the id hash
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old_hmac_sha256_ids = (RepoKey, KeyfileKey)
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new_hmac_sha256_ids = (AESOCBRepoKey, AESOCBKeyfileKey, CHPORepoKey, CHPOKeyfileKey)
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old_blake2_ids = (Blake2RepoKey, Blake2KeyfileKey)
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new_blake2_ids = (Blake2AESOCBRepoKey, Blake2AESOCBKeyfileKey, Blake2CHPORepoKey, Blake2CHPOKeyfileKey)
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same_ids = (
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isinstance(other_key, old_hmac_sha256_ids + new_hmac_sha256_ids) and isinstance(key, new_hmac_sha256_ids)
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or
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isinstance(other_key, old_blake2_ids + new_blake2_ids) and isinstance(key, new_blake2_ids)
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)
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return same_ids
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class KeyBase:
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# Numeric key type ID, must fit in one byte.
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TYPE = None # override in subclasses
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# set of key type IDs the class can handle as input
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TYPES_ACCEPTABLE = None # override in subclasses
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# Human-readable name
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NAME = 'UNDEFINED'
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# Name used in command line / API (e.g. borg init --encryption=...)
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ARG_NAME = 'UNDEFINED'
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# Storage type (no key blob storage / keyfile / repo)
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STORAGE = KeyBlobStorage.NO_STORAGE
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# Seed for the buzhash chunker (borg.algorithms.chunker.Chunker)
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# type: int
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chunk_seed = None
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# Whether this *particular instance* is encrypted from a practical point of view,
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# i.e. when it's using encryption with a empty passphrase, then
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# that may be *technically* called encryption, but for all intents and purposes
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# that's as good as not encrypting in the first place, and this member should be False.
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#
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# The empty passphrase is also special because Borg tries it first when no passphrase
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# was supplied, and if an empty passphrase works, then Borg won't ask for one.
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logically_encrypted = False
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def __init__(self, repository):
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self.TYPE_STR = bytes([self.TYPE])
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self.repository = repository
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self.target = None # key location file path / repo obj
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# Some commands write new chunks (e.g. rename) but don't take a --compression argument. This duplicates
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# the default used by those commands who do take a --compression argument.
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self.compressor = Compressor('lz4')
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self.decompress = self.compressor.decompress
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self.tam_required = True
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def id_hash(self, data):
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"""Return HMAC hash using the "id" HMAC key
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"""
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raise NotImplementedError
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def encrypt(self, id, data, compress=True):
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pass
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def decrypt(self, id, data, decompress=True):
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pass
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def assert_id(self, id, data):
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if id and id != Manifest.MANIFEST_ID:
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id_computed = self.id_hash(data)
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if not hmac.compare_digest(id_computed, id):
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raise IntegrityError('Chunk %s: id verification failed' % bin_to_hex(id))
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def assert_type(self, type_byte, id=None):
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if type_byte not in self.TYPES_ACCEPTABLE:
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id_str = bin_to_hex(id) if id is not None else '(unknown)'
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raise IntegrityError(f'Chunk {id_str}: Invalid encryption envelope')
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def _tam_key(self, salt, context):
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return hkdf_hmac_sha512(
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ikm=self.id_key + self.enc_key + self.enc_hmac_key,
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salt=salt,
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info=b'borg-metadata-authentication-' + context,
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output_length=64
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)
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def pack_and_authenticate_metadata(self, metadata_dict, context=b'manifest'):
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metadata_dict = StableDict(metadata_dict)
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tam = metadata_dict['tam'] = StableDict({
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'type': 'HKDF_HMAC_SHA512',
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'hmac': bytes(64),
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'salt': os.urandom(64),
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})
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packed = msgpack.packb(metadata_dict)
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tam_key = self._tam_key(tam['salt'], context)
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tam['hmac'] = hmac.digest(tam_key, packed, 'sha512')
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return msgpack.packb(metadata_dict)
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def unpack_and_verify_manifest(self, data, force_tam_not_required=False):
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"""Unpack msgpacked *data* and return (object, did_verify)."""
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if data.startswith(b'\xc1' * 4):
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# This is a manifest from the future, we can't read it.
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raise UnsupportedManifestError()
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tam_required = self.tam_required
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if force_tam_not_required and tam_required:
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logger.warning('Manifest authentication DISABLED.')
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tam_required = False
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data = bytearray(data)
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unpacker = get_limited_unpacker('manifest')
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unpacker.feed(data)
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unpacked = unpacker.unpack()
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if 'tam' not in unpacked:
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if tam_required:
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raise TAMRequiredError(self.repository._location.canonical_path())
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else:
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logger.debug('TAM not found and not required')
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return unpacked, False
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tam = unpacked.pop('tam', None)
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if not isinstance(tam, dict):
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raise TAMInvalid()
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tam_type = tam.get('type', '<none>')
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if tam_type != 'HKDF_HMAC_SHA512':
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if tam_required:
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raise TAMUnsupportedSuiteError(repr(tam_type))
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else:
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logger.debug('Ignoring TAM made with unsupported suite, since TAM is not required: %r', tam_type)
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return unpacked, False
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tam_hmac = tam.get('hmac')
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tam_salt = tam.get('salt')
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if not isinstance(tam_salt, (bytes, str)) or not isinstance(tam_hmac, (bytes, str)):
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raise TAMInvalid()
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tam_hmac = want_bytes(tam_hmac) # legacy
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tam_salt = want_bytes(tam_salt) # legacy
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offset = data.index(tam_hmac)
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data[offset:offset + 64] = bytes(64)
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tam_key = self._tam_key(tam_salt, context=b'manifest')
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calculated_hmac = hmac.digest(tam_key, data, 'sha512')
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if not hmac.compare_digest(calculated_hmac, tam_hmac):
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raise TAMInvalid()
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logger.debug('TAM-verified manifest')
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return unpacked, True
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class PlaintextKey(KeyBase):
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TYPE = KeyType.PLAINTEXT
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TYPES_ACCEPTABLE = {TYPE}
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NAME = 'plaintext'
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ARG_NAME = 'none'
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STORAGE = KeyBlobStorage.NO_STORAGE
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chunk_seed = 0
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logically_encrypted = False
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def __init__(self, repository):
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super().__init__(repository)
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self.tam_required = False
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@classmethod
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def create(cls, repository, args, **kw):
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logger.info('Encryption NOT enabled.\nUse the "--encryption=repokey|keyfile" to enable encryption.')
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return cls(repository)
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@classmethod
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def detect(cls, repository, manifest_data):
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return cls(repository)
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def id_hash(self, data):
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return sha256(data).digest()
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def encrypt(self, id, data, compress=True):
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if compress:
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data = self.compressor.compress(data)
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return b''.join([self.TYPE_STR, data])
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def decrypt(self, id, data, decompress=True):
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self.assert_type(data[0], id)
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payload = memoryview(data)[1:]
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if not decompress:
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return payload
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data = self.decompress(payload)
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self.assert_id(id, data)
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return data
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def _tam_key(self, salt, context):
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return salt + context
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def random_blake2b_256_key():
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# This might look a bit curious, but is the same construction used in the keyed mode of BLAKE2b.
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# Why limit the key to 64 bytes and pad it with 64 nulls nonetheless? The answer is that BLAKE2b
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# has a 128 byte block size, but only 64 bytes of internal state (this is also referred to as a
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# "local wide pipe" design, because the compression function transforms (block, state) => state,
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# and len(block) >= len(state), hence wide.)
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# In other words, a key longer than 64 bytes would have simply no advantage, since the function
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# has no way of propagating more than 64 bytes of entropy internally.
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# It's padded to a full block so that the key is never buffered internally by blake2b_update, ie.
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# it remains in a single memory location that can be tracked and could be erased securely, if we
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# wanted to.
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return os.urandom(64) + bytes(64)
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class ID_BLAKE2b_256:
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"""
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Key mix-in class for using BLAKE2b-256 for the id key.
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The id_key length must be 32 bytes.
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"""
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def id_hash(self, data):
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return blake2b_256(self.id_key, data)
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def init_from_random_data(self):
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super().init_from_random_data()
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self.enc_hmac_key = random_blake2b_256_key()
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self.id_key = random_blake2b_256_key()
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class ID_HMAC_SHA_256:
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"""
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Key mix-in class for using HMAC-SHA-256 for the id key.
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The id_key length must be 32 bytes.
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"""
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def id_hash(self, data):
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return hmac_sha256(self.id_key, data)
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class AESKeyBase(KeyBase):
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"""
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Chunks are encrypted using 256bit AES in Counter Mode (CTR)
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Payload layout: TYPE(1) + HMAC(32) + NONCE(8) + CIPHERTEXT
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To reduce payload size only 8 bytes of the 16 bytes nonce is saved
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in the payload, the first 8 bytes are always zeros. This does not
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affect security but limits the maximum repository capacity to
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only 295 exabytes!
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"""
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PAYLOAD_OVERHEAD = 1 + 32 + 8 # TYPE + HMAC + NONCE
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CIPHERSUITE = None # override in derived class
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logically_encrypted = True
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def encrypt(self, id, data, compress=True):
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if compress:
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data = self.compressor.compress(data)
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next_iv = self.nonce_manager.ensure_reservation(self.cipher.next_iv(),
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self.cipher.block_count(len(data)))
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return self.cipher.encrypt(data, header=self.TYPE_STR, iv=next_iv)
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def decrypt(self, id, data, decompress=True):
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self.assert_type(data[0], id)
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try:
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payload = self.cipher.decrypt(data)
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except IntegrityError as e:
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raise IntegrityError(f"Chunk {bin_to_hex(id)}: Could not decrypt [{str(e)}]")
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if not decompress:
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return payload
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data = self.decompress(memoryview(payload))
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self.assert_id(id, data)
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return data
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def init_from_given_data(self, *, enc_key, enc_hmac_key, id_key, chunk_seed):
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assert len(enc_key) >= 32
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assert len(enc_hmac_key) >= 32
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assert len(id_key) >= 32
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assert isinstance(chunk_seed, int)
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self.enc_key = enc_key
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self.enc_hmac_key = enc_hmac_key
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self.id_key = id_key
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self.chunk_seed = chunk_seed
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def init_from_random_data(self):
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data = os.urandom(100)
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chunk_seed = bytes_to_int(data[96:100])
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# Convert to signed int32
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if chunk_seed & 0x80000000:
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chunk_seed = chunk_seed - 0xffffffff - 1
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self.init_from_given_data(
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enc_key=data[0:32],
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enc_hmac_key=data[32:64],
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id_key=data[64:96],
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chunk_seed=chunk_seed)
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def init_ciphers(self, manifest_data=None):
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self.cipher = self.CIPHERSUITE(mac_key=self.enc_hmac_key, enc_key=self.enc_key, header_len=1, aad_offset=1)
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if manifest_data is None:
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nonce = 0
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else:
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self.assert_type(manifest_data[0])
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# manifest_blocks is a safe upper bound on the amount of cipher blocks needed
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# to encrypt the manifest. depending on the ciphersuite and overhead, it might
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# be a bit too high, but that does not matter.
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manifest_blocks = num_cipher_blocks(len(manifest_data))
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nonce = self.cipher.extract_iv(manifest_data) + manifest_blocks
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self.cipher.set_iv(nonce)
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self.nonce_manager = NonceManager(self.repository, nonce)
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class FlexiKey:
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FILE_ID = 'BORG_KEY'
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@classmethod
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def detect(cls, repository, manifest_data):
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key = cls(repository)
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target = key.find_key()
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prompt = 'Enter passphrase for key %s: ' % target
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passphrase = Passphrase.env_passphrase()
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if passphrase is None:
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passphrase = Passphrase()
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if not key.load(target, passphrase):
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for retry in range(0, 3):
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passphrase = Passphrase.getpass(prompt)
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if key.load(target, passphrase):
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break
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else:
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raise PasswordRetriesExceeded
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else:
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if not key.load(target, passphrase):
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raise PassphraseWrong
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key.init_ciphers(manifest_data)
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key._passphrase = passphrase
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return key
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def _load(self, key_data, passphrase):
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cdata = a2b_base64(key_data)
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data = self.decrypt_key_file(cdata, passphrase)
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if data:
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data = msgpack.unpackb(data)
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key = Key(internal_dict=data)
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if key.version != 1:
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raise IntegrityError('Invalid key file header')
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self.repository_id = key.repository_id
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self.enc_key = key.enc_key
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self.enc_hmac_key = key.enc_hmac_key
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self.id_key = key.id_key
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self.chunk_seed = key.chunk_seed
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self.tam_required = key.get('tam_required', tam_required(self.repository))
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return True
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return False
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def decrypt_key_file(self, data, passphrase):
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unpacker = get_limited_unpacker('key')
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unpacker.feed(data)
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data = unpacker.unpack()
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encrypted_key = EncryptedKey(internal_dict=data)
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if encrypted_key.version != 1:
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raise UnsupportedKeyFormatError()
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else:
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self._encrypted_key_algorithm = encrypted_key.algorithm
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if encrypted_key.algorithm == 'sha256':
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return self.decrypt_key_file_pbkdf2(encrypted_key, passphrase)
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elif encrypted_key.algorithm == 'argon2 chacha20-poly1305':
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return self.decrypt_key_file_argon2(encrypted_key, passphrase)
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else:
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raise UnsupportedKeyFormatError()
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@staticmethod
|
|
def pbkdf2(passphrase, salt, iterations, output_len_in_bytes):
|
|
if os.environ.get("BORG_TESTONLY_WEAKEN_KDF") == "1":
|
|
iterations = 1
|
|
return pbkdf2_hmac('sha256', passphrase.encode('utf-8'), salt, iterations, output_len_in_bytes)
|
|
|
|
@staticmethod
|
|
def argon2(
|
|
passphrase: str,
|
|
output_len_in_bytes: int,
|
|
salt: bytes,
|
|
time_cost: int,
|
|
memory_cost: int,
|
|
parallelism: int,
|
|
type: Literal['i', 'd', 'id']
|
|
) -> bytes:
|
|
if os.environ.get("BORG_TESTONLY_WEAKEN_KDF") == "1":
|
|
time_cost = 1
|
|
parallelism = 1
|
|
# 8 is the smallest value that avoids the "Memory cost is too small" exception
|
|
memory_cost = 8
|
|
type_map = {
|
|
'i': argon2.low_level.Type.I,
|
|
'd': argon2.low_level.Type.D,
|
|
'id': argon2.low_level.Type.ID,
|
|
}
|
|
key = argon2.low_level.hash_secret_raw(
|
|
secret=passphrase.encode("utf-8"),
|
|
hash_len=output_len_in_bytes,
|
|
salt=salt,
|
|
time_cost=time_cost,
|
|
memory_cost=memory_cost,
|
|
parallelism=parallelism,
|
|
type=type_map[type],
|
|
)
|
|
return key
|
|
|
|
def decrypt_key_file_pbkdf2(self, encrypted_key, passphrase):
|
|
key = self.pbkdf2(passphrase, encrypted_key.salt, encrypted_key.iterations, 32)
|
|
data = AES(key, b'\0'*16).decrypt(encrypted_key.data)
|
|
if hmac.compare_digest(hmac_sha256(key, data), encrypted_key.hash):
|
|
return data
|
|
return None
|
|
|
|
def decrypt_key_file_argon2(self, encrypted_key, passphrase):
|
|
key = self.argon2(
|
|
passphrase,
|
|
output_len_in_bytes=32,
|
|
salt=encrypted_key.salt,
|
|
time_cost=encrypted_key.argon2_time_cost,
|
|
memory_cost=encrypted_key.argon2_memory_cost,
|
|
parallelism=encrypted_key.argon2_parallelism,
|
|
type=encrypted_key.argon2_type,
|
|
)
|
|
ae_cipher = CHACHA20_POLY1305(key=key, iv=0, header_len=0, aad_offset=0)
|
|
try:
|
|
return ae_cipher.decrypt(encrypted_key.data)
|
|
except low_level.IntegrityError:
|
|
return None
|
|
|
|
def encrypt_key_file(self, data, passphrase, algorithm):
|
|
if algorithm == 'sha256':
|
|
return self.encrypt_key_file_pbkdf2(data, passphrase)
|
|
elif algorithm == 'argon2 chacha20-poly1305':
|
|
return self.encrypt_key_file_argon2(data, passphrase)
|
|
else:
|
|
raise ValueError(f'Unexpected algorithm: {algorithm}')
|
|
|
|
def encrypt_key_file_pbkdf2(self, data, passphrase):
|
|
salt = os.urandom(32)
|
|
iterations = PBKDF2_ITERATIONS
|
|
key = self.pbkdf2(passphrase, salt, iterations, 32)
|
|
hash = hmac_sha256(key, data)
|
|
cdata = AES(key, b'\0'*16).encrypt(data)
|
|
enc_key = EncryptedKey(
|
|
version=1,
|
|
salt=salt,
|
|
iterations=iterations,
|
|
algorithm='sha256',
|
|
hash=hash,
|
|
data=cdata,
|
|
)
|
|
return msgpack.packb(enc_key.as_dict())
|
|
|
|
def encrypt_key_file_argon2(self, data, passphrase):
|
|
salt = os.urandom(ARGON2_SALT_BYTES)
|
|
key = self.argon2(
|
|
passphrase,
|
|
output_len_in_bytes=32,
|
|
salt=salt,
|
|
**ARGON2_ARGS,
|
|
)
|
|
ae_cipher = CHACHA20_POLY1305(key=key, iv=0, header_len=0, aad_offset=0)
|
|
encrypted_key = EncryptedKey(
|
|
version=1,
|
|
algorithm='argon2 chacha20-poly1305',
|
|
salt=salt,
|
|
data=ae_cipher.encrypt(data),
|
|
**{'argon2_' + k: v for k, v in ARGON2_ARGS.items()},
|
|
)
|
|
return msgpack.packb(encrypted_key.as_dict())
|
|
|
|
def _save(self, passphrase, algorithm):
|
|
key = Key(
|
|
version=1,
|
|
repository_id=self.repository_id,
|
|
enc_key=self.enc_key,
|
|
enc_hmac_key=self.enc_hmac_key,
|
|
id_key=self.id_key,
|
|
chunk_seed=self.chunk_seed,
|
|
tam_required=self.tam_required,
|
|
)
|
|
data = self.encrypt_key_file(msgpack.packb(key.as_dict()), passphrase, algorithm)
|
|
key_data = '\n'.join(textwrap.wrap(b2a_base64(data).decode('ascii')))
|
|
return key_data
|
|
|
|
def change_passphrase(self, passphrase=None):
|
|
if passphrase is None:
|
|
passphrase = Passphrase.new(allow_empty=True)
|
|
self.save(self.target, passphrase, algorithm=self._encrypted_key_algorithm)
|
|
|
|
@classmethod
|
|
def create(cls, repository, args, *, other_key=None):
|
|
key = cls(repository)
|
|
key.repository_id = repository.id
|
|
if other_key is not None:
|
|
if isinstance(other_key, PlaintextKey):
|
|
raise Error("Copying key material from an unencrypted repository is not possible.")
|
|
if isinstance(key, AESKeyBase):
|
|
# user must use an AEADKeyBase subclass (AEAD modes with session keys)
|
|
raise Error("Copying key material to an AES-CTR based mode is insecure and unsupported.")
|
|
if not uses_same_id_hash(other_key, key):
|
|
raise Error("You must keep the same ID hash (HMAC-SHA256 or BLAKE2b) or deduplication will break.")
|
|
key.init_from_given_data(
|
|
enc_key=other_key.enc_key,
|
|
enc_hmac_key=other_key.enc_hmac_key,
|
|
id_key=other_key.id_key,
|
|
chunk_seed=other_key.chunk_seed)
|
|
passphrase = other_key._passphrase
|
|
else:
|
|
key.init_from_random_data()
|
|
passphrase = Passphrase.new(allow_empty=True)
|
|
key.init_ciphers()
|
|
target = key.get_new_target(args)
|
|
key.save(target, passphrase, create=True, algorithm=KEY_ALGORITHMS[args.key_algorithm])
|
|
logger.info('Key in "%s" created.' % target)
|
|
logger.info('Keep this key safe. Your data will be inaccessible without it.')
|
|
return key
|
|
|
|
def sanity_check(self, filename, id):
|
|
file_id = self.FILE_ID.encode() + b' '
|
|
repo_id = hexlify(id)
|
|
with open(filename, 'rb') as fd:
|
|
# we do the magic / id check in binary mode to avoid stumbling over
|
|
# decoding errors if somebody has binary files in the keys dir for some reason.
|
|
if fd.read(len(file_id)) != file_id:
|
|
raise KeyfileInvalidError(self.repository._location.canonical_path(), filename)
|
|
if fd.read(len(repo_id)) != repo_id:
|
|
raise KeyfileMismatchError(self.repository._location.canonical_path(), filename)
|
|
return filename
|
|
|
|
def find_key(self):
|
|
if self.STORAGE == KeyBlobStorage.KEYFILE:
|
|
keyfile = self._find_key_file_from_environment()
|
|
if keyfile is not None:
|
|
return self.sanity_check(keyfile, self.repository.id)
|
|
keyfile = self._find_key_in_keys_dir()
|
|
if keyfile is not None:
|
|
return keyfile
|
|
raise KeyfileNotFoundError(self.repository._location.canonical_path(), get_keys_dir())
|
|
elif self.STORAGE == KeyBlobStorage.REPO:
|
|
loc = self.repository._location.canonical_path()
|
|
key = self.repository.load_key()
|
|
if not key:
|
|
# if we got an empty key, it means there is no key.
|
|
raise RepoKeyNotFoundError(loc) from None
|
|
return loc
|
|
else:
|
|
raise TypeError('Unsupported borg key storage type')
|
|
|
|
def get_existing_or_new_target(self, args):
|
|
keyfile = self._find_key_file_from_environment()
|
|
if keyfile is not None:
|
|
return keyfile
|
|
keyfile = self._find_key_in_keys_dir()
|
|
if keyfile is not None:
|
|
return keyfile
|
|
return self._get_new_target_in_keys_dir(args)
|
|
|
|
def _find_key_in_keys_dir(self):
|
|
id = self.repository.id
|
|
keys_dir = get_keys_dir()
|
|
for name in os.listdir(keys_dir):
|
|
filename = os.path.join(keys_dir, name)
|
|
try:
|
|
return self.sanity_check(filename, id)
|
|
except (KeyfileInvalidError, KeyfileMismatchError):
|
|
pass
|
|
|
|
def get_new_target(self, args):
|
|
if self.STORAGE == KeyBlobStorage.KEYFILE:
|
|
keyfile = self._find_key_file_from_environment()
|
|
if keyfile is not None:
|
|
return keyfile
|
|
return self._get_new_target_in_keys_dir(args)
|
|
elif self.STORAGE == KeyBlobStorage.REPO:
|
|
return self.repository
|
|
else:
|
|
raise TypeError('Unsupported borg key storage type')
|
|
|
|
def _find_key_file_from_environment(self):
|
|
keyfile = os.environ.get('BORG_KEY_FILE')
|
|
if keyfile:
|
|
return os.path.abspath(keyfile)
|
|
|
|
def _get_new_target_in_keys_dir(self, args):
|
|
filename = args.location.to_key_filename()
|
|
path = filename
|
|
i = 1
|
|
while os.path.exists(path):
|
|
i += 1
|
|
path = filename + '.%d' % i
|
|
return path
|
|
|
|
def load(self, target, passphrase):
|
|
if self.STORAGE == KeyBlobStorage.KEYFILE:
|
|
with open(target) as fd:
|
|
key_data = ''.join(fd.readlines()[1:])
|
|
elif self.STORAGE == KeyBlobStorage.REPO:
|
|
# While the repository is encrypted, we consider a repokey repository with a blank
|
|
# passphrase an unencrypted repository.
|
|
self.logically_encrypted = passphrase != ''
|
|
|
|
# what we get in target is just a repo location, but we already have the repo obj:
|
|
target = self.repository
|
|
key_data = target.load_key()
|
|
if not key_data:
|
|
# if we got an empty key, it means there is no key.
|
|
loc = target._location.canonical_path()
|
|
raise RepoKeyNotFoundError(loc) from None
|
|
key_data = key_data.decode('utf-8') # remote repo: msgpack issue #99, getting bytes
|
|
else:
|
|
raise TypeError('Unsupported borg key storage type')
|
|
success = self._load(key_data, passphrase)
|
|
if success:
|
|
self.target = target
|
|
return success
|
|
|
|
def save(self, target, passphrase, algorithm, create=False):
|
|
key_data = self._save(passphrase, algorithm)
|
|
if self.STORAGE == KeyBlobStorage.KEYFILE:
|
|
if create and os.path.isfile(target):
|
|
# if a new keyfile key repository is created, ensure that an existing keyfile of another
|
|
# keyfile key repo is not accidentally overwritten by careless use of the BORG_KEY_FILE env var.
|
|
# see issue #6036
|
|
raise Error('Aborting because key in "%s" already exists.' % target)
|
|
with SaveFile(target) as fd:
|
|
fd.write(f'{self.FILE_ID} {bin_to_hex(self.repository_id)}\n')
|
|
fd.write(key_data)
|
|
fd.write('\n')
|
|
elif self.STORAGE == KeyBlobStorage.REPO:
|
|
self.logically_encrypted = passphrase != ''
|
|
key_data = key_data.encode('utf-8') # remote repo: msgpack issue #99, giving bytes
|
|
target.save_key(key_data)
|
|
else:
|
|
raise TypeError('Unsupported borg key storage type')
|
|
self.target = target
|
|
|
|
def remove(self, target):
|
|
if self.STORAGE == KeyBlobStorage.KEYFILE:
|
|
os.remove(target)
|
|
elif self.STORAGE == KeyBlobStorage.REPO:
|
|
target.save_key(b'') # save empty key (no new api at remote repo necessary)
|
|
else:
|
|
raise TypeError('Unsupported borg key storage type')
|
|
|
|
|
|
class KeyfileKey(ID_HMAC_SHA_256, AESKeyBase, FlexiKey):
|
|
TYPES_ACCEPTABLE = {KeyType.KEYFILE, KeyType.REPO, KeyType.PASSPHRASE}
|
|
TYPE = KeyType.KEYFILE
|
|
NAME = 'key file'
|
|
ARG_NAME = 'keyfile'
|
|
STORAGE = KeyBlobStorage.KEYFILE
|
|
CIPHERSUITE = AES256_CTR_HMAC_SHA256
|
|
|
|
|
|
class RepoKey(ID_HMAC_SHA_256, AESKeyBase, FlexiKey):
|
|
TYPES_ACCEPTABLE = {KeyType.KEYFILE, KeyType.REPO, KeyType.PASSPHRASE}
|
|
TYPE = KeyType.REPO
|
|
NAME = 'repokey'
|
|
ARG_NAME = 'repokey'
|
|
STORAGE = KeyBlobStorage.REPO
|
|
CIPHERSUITE = AES256_CTR_HMAC_SHA256
|
|
|
|
|
|
class Blake2KeyfileKey(ID_BLAKE2b_256, AESKeyBase, FlexiKey):
|
|
TYPES_ACCEPTABLE = {KeyType.BLAKE2KEYFILE, KeyType.BLAKE2REPO}
|
|
TYPE = KeyType.BLAKE2KEYFILE
|
|
NAME = 'key file BLAKE2b'
|
|
ARG_NAME = 'keyfile-blake2'
|
|
STORAGE = KeyBlobStorage.KEYFILE
|
|
CIPHERSUITE = AES256_CTR_BLAKE2b
|
|
|
|
|
|
class Blake2RepoKey(ID_BLAKE2b_256, AESKeyBase, FlexiKey):
|
|
TYPES_ACCEPTABLE = {KeyType.BLAKE2KEYFILE, KeyType.BLAKE2REPO}
|
|
TYPE = KeyType.BLAKE2REPO
|
|
NAME = 'repokey BLAKE2b'
|
|
ARG_NAME = 'repokey-blake2'
|
|
STORAGE = KeyBlobStorage.REPO
|
|
CIPHERSUITE = AES256_CTR_BLAKE2b
|
|
|
|
|
|
class AuthenticatedKeyBase(AESKeyBase, FlexiKey):
|
|
STORAGE = KeyBlobStorage.REPO
|
|
|
|
# It's only authenticated, not encrypted.
|
|
logically_encrypted = False
|
|
|
|
def load(self, target, passphrase):
|
|
success = super().load(target, passphrase)
|
|
self.logically_encrypted = False
|
|
return success
|
|
|
|
def save(self, target, passphrase, algorithm, create=False):
|
|
super().save(target, passphrase, algorithm, create=create)
|
|
self.logically_encrypted = False
|
|
|
|
def init_ciphers(self, manifest_data=None):
|
|
if manifest_data is not None:
|
|
self.assert_type(manifest_data[0])
|
|
|
|
def encrypt(self, id, data, compress=True):
|
|
if compress:
|
|
data = self.compressor.compress(data)
|
|
return b''.join([self.TYPE_STR, data])
|
|
|
|
def decrypt(self, id, data, decompress=True):
|
|
self.assert_type(data[0], id)
|
|
payload = memoryview(data)[1:]
|
|
if not decompress:
|
|
return payload
|
|
data = self.decompress(payload)
|
|
self.assert_id(id, data)
|
|
return data
|
|
|
|
|
|
class AuthenticatedKey(ID_HMAC_SHA_256, AuthenticatedKeyBase):
|
|
TYPE = KeyType.AUTHENTICATED
|
|
TYPES_ACCEPTABLE = {TYPE}
|
|
NAME = 'authenticated'
|
|
ARG_NAME = 'authenticated'
|
|
|
|
|
|
class Blake2AuthenticatedKey(ID_BLAKE2b_256, AuthenticatedKeyBase):
|
|
TYPE = KeyType.BLAKE2AUTHENTICATED
|
|
TYPES_ACCEPTABLE = {TYPE}
|
|
NAME = 'authenticated BLAKE2b'
|
|
ARG_NAME = 'authenticated-blake2'
|
|
|
|
|
|
# ------------ new crypto ------------
|
|
|
|
|
|
class AEADKeyBase(KeyBase):
|
|
"""
|
|
Chunks are encrypted and authenticated using some AEAD ciphersuite
|
|
|
|
Layout: suite:4 keytype:4 reserved:8 messageIV:48 sessionID:192 auth_tag:128 payload:... [bits]
|
|
^-------------------- AAD ----------------------------^
|
|
Offsets:0 1 2 8 32 48 [bytes]
|
|
|
|
suite: 1010b for new AEAD crypto, 0000b is old crypto
|
|
keytype: see constants.KeyType (suite+keytype)
|
|
reserved: all-zero, for future use
|
|
messageIV: a counter starting from 0 for all new encrypted messages of one session
|
|
sessionID: 192bit random, computed once per session (the session key is derived from this)
|
|
auth_tag: authentication tag output of the AEAD cipher (computed over payload and AAD)
|
|
payload: encrypted chunk data
|
|
"""
|
|
|
|
PAYLOAD_OVERHEAD = 1 + 1 + 6 + 24 + 16 # [bytes], see Layout
|
|
|
|
CIPHERSUITE = None # override in subclass
|
|
|
|
logically_encrypted = True
|
|
|
|
MAX_IV = 2 ** 48 - 1
|
|
|
|
def encrypt(self, id, data, compress=True):
|
|
# to encrypt new data in this session we use always self.cipher and self.sessionid
|
|
if compress:
|
|
data = self.compressor.compress(data)
|
|
reserved = b'\0'
|
|
iv = self.cipher.next_iv()
|
|
if iv > self.MAX_IV: # see the data-structures docs about why the IV range is enough
|
|
raise IntegrityError("IV overflow, should never happen.")
|
|
iv_48bit = iv.to_bytes(6, 'big')
|
|
header = self.TYPE_STR + reserved + iv_48bit + self.sessionid
|
|
return self.cipher.encrypt(data, header=header, iv=iv, aad=id)
|
|
|
|
def decrypt(self, id, data, decompress=True):
|
|
# to decrypt existing data, we need to get a cipher configured for the sessionid and iv from header
|
|
self.assert_type(data[0], id)
|
|
iv_48bit = data[2:8]
|
|
sessionid = data[8:32]
|
|
iv = int.from_bytes(iv_48bit, 'big')
|
|
cipher = self._get_cipher(sessionid, iv)
|
|
try:
|
|
payload = cipher.decrypt(data, aad=id)
|
|
except IntegrityError as e:
|
|
raise IntegrityError(f"Chunk {bin_to_hex(id)}: Could not decrypt [{str(e)}]")
|
|
if not decompress:
|
|
return payload
|
|
data = self.decompress(memoryview(payload))
|
|
self.assert_id(id, data)
|
|
return data
|
|
|
|
def init_from_given_data(self, *, enc_key, enc_hmac_key, id_key, chunk_seed):
|
|
assert len(enc_key) >= 32
|
|
assert len(enc_hmac_key) >= 32
|
|
assert len(id_key) >= 32
|
|
assert isinstance(chunk_seed, int)
|
|
self.enc_key = enc_key
|
|
self.enc_hmac_key = enc_hmac_key
|
|
self.id_key = id_key
|
|
self.chunk_seed = chunk_seed
|
|
|
|
def init_from_random_data(self):
|
|
data = os.urandom(100)
|
|
chunk_seed = bytes_to_int(data[96:100])
|
|
# Convert to signed int32
|
|
if chunk_seed & 0x80000000:
|
|
chunk_seed = chunk_seed - 0xffffffff - 1
|
|
self.init_from_given_data(
|
|
enc_key=data[0:32],
|
|
enc_hmac_key=data[32:64],
|
|
id_key=data[64:96],
|
|
chunk_seed=chunk_seed)
|
|
|
|
def _get_session_key(self, sessionid):
|
|
assert len(sessionid) == 24 # 192bit
|
|
key = hkdf_hmac_sha512(
|
|
ikm=self.enc_key + self.enc_hmac_key,
|
|
salt=sessionid,
|
|
info=b'borg-session-key-' + self.CIPHERSUITE.__name__.encode(),
|
|
output_length=32
|
|
)
|
|
return key
|
|
|
|
def _get_cipher(self, sessionid, iv):
|
|
assert isinstance(iv, int)
|
|
key = self._get_session_key(sessionid)
|
|
cipher = self.CIPHERSUITE(key=key, iv=iv, header_len=1+1+6+24, aad_offset=0)
|
|
return cipher
|
|
|
|
def init_ciphers(self, manifest_data=None, iv=0):
|
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# in every new session we start with a fresh sessionid and at iv == 0, manifest_data and iv params are ignored
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self.sessionid = os.urandom(24)
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self.cipher = self._get_cipher(self.sessionid, iv=0)
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class AESOCBKeyfileKey(ID_HMAC_SHA_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.AESOCBKEYFILE, KeyType.AESOCBREPO}
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TYPE = KeyType.AESOCBKEYFILE
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NAME = 'key file AES-OCB'
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ARG_NAME = 'keyfile-aes-ocb'
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STORAGE = KeyBlobStorage.KEYFILE
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CIPHERSUITE = AES256_OCB
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class AESOCBRepoKey(ID_HMAC_SHA_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.AESOCBKEYFILE, KeyType.AESOCBREPO}
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TYPE = KeyType.AESOCBREPO
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NAME = 'repokey AES-OCB'
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ARG_NAME = 'repokey-aes-ocb'
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STORAGE = KeyBlobStorage.REPO
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CIPHERSUITE = AES256_OCB
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class CHPOKeyfileKey(ID_HMAC_SHA_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.CHPOKEYFILE, KeyType.CHPOREPO}
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TYPE = KeyType.CHPOKEYFILE
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NAME = 'key file ChaCha20-Poly1305'
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ARG_NAME = 'keyfile-chacha20-poly1305'
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STORAGE = KeyBlobStorage.KEYFILE
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CIPHERSUITE = CHACHA20_POLY1305
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class CHPORepoKey(ID_HMAC_SHA_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.CHPOKEYFILE, KeyType.CHPOREPO}
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TYPE = KeyType.CHPOREPO
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NAME = 'repokey ChaCha20-Poly1305'
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ARG_NAME = 'repokey-chacha20-poly1305'
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STORAGE = KeyBlobStorage.REPO
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CIPHERSUITE = CHACHA20_POLY1305
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class Blake2AESOCBKeyfileKey(ID_BLAKE2b_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.BLAKE2AESOCBKEYFILE, KeyType.BLAKE2AESOCBREPO}
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TYPE = KeyType.BLAKE2AESOCBKEYFILE
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NAME = 'key file Blake2b AES-OCB'
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ARG_NAME = 'keyfile-blake2-aes-ocb'
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STORAGE = KeyBlobStorage.KEYFILE
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CIPHERSUITE = AES256_OCB
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class Blake2AESOCBRepoKey(ID_BLAKE2b_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.BLAKE2AESOCBKEYFILE, KeyType.BLAKE2AESOCBREPO}
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TYPE = KeyType.BLAKE2AESOCBREPO
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NAME = 'repokey Blake2b AES-OCB'
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ARG_NAME = 'repokey-blake2-aes-ocb'
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STORAGE = KeyBlobStorage.REPO
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CIPHERSUITE = AES256_OCB
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class Blake2CHPOKeyfileKey(ID_BLAKE2b_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.BLAKE2CHPOKEYFILE, KeyType.BLAKE2CHPOREPO}
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TYPE = KeyType.BLAKE2CHPOKEYFILE
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NAME = 'key file Blake2b ChaCha20-Poly1305'
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ARG_NAME = 'keyfile-blake2-chacha20-poly1305'
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STORAGE = KeyBlobStorage.KEYFILE
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CIPHERSUITE = CHACHA20_POLY1305
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class Blake2CHPORepoKey(ID_BLAKE2b_256, AEADKeyBase, FlexiKey):
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TYPES_ACCEPTABLE = {KeyType.BLAKE2CHPOKEYFILE, KeyType.BLAKE2CHPOREPO}
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TYPE = KeyType.BLAKE2CHPOREPO
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NAME = 'repokey Blake2b ChaCha20-Poly1305'
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ARG_NAME = 'repokey-blake2-chacha20-poly1305'
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STORAGE = KeyBlobStorage.REPO
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CIPHERSUITE = CHACHA20_POLY1305
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AVAILABLE_KEY_TYPES = (
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PlaintextKey,
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KeyfileKey, RepoKey, AuthenticatedKey,
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Blake2KeyfileKey, Blake2RepoKey, Blake2AuthenticatedKey,
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# new crypto
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AESOCBKeyfileKey, AESOCBRepoKey,
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CHPOKeyfileKey, CHPORepoKey,
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Blake2AESOCBKeyfileKey, Blake2AESOCBRepoKey,
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Blake2CHPOKeyfileKey, Blake2CHPORepoKey,
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)
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