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from binascii import unhexlify, a2b_base64, b2a_base64
import binascii
import textwrap
from hashlib import sha256
from .key import KeyfileKey, RepoKey, PassphraseKey, KeyfileNotFoundError, PlaintextKey
from .helpers import Manifest, NoManifestError, Error, yes, bin_to_hex
from .repository import Repository
class UnencryptedRepo(Error):
"""Keymanagement not available for unencrypted repositories."""
class UnknownKeyType(Error):
"""Keytype {0} is unknown."""
class RepoIdMismatch(Error):
"""This key backup seems to be for a different backup repository, aborting."""
class NotABorgKeyFile(Error):
"""This file is not a borg key backup, aborting."""
def sha256_truncated(data, num):
h = sha256()
h.update(data)
return h.hexdigest()[:num]
KEYBLOB_LOCAL = 'local'
KEYBLOB_REPO = 'repo'
class KeyManager:
def __init__(self, repository):
self.repository = repository
self.keyblob = None
self.keyblob_storage = None
try:
cdata = self.repository.get(Manifest.MANIFEST_ID)
except Repository.ObjectNotFound:
raise NoManifestError
key_type = cdata[0]
if key_type == KeyfileKey.TYPE:
self.keyblob_storage = KEYBLOB_LOCAL
elif key_type == RepoKey.TYPE or key_type == PassphraseKey.TYPE:
self.keyblob_storage = KEYBLOB_REPO
elif key_type == PlaintextKey.TYPE:
raise UnencryptedRepo()
else:
raise UnknownKeyType(key_type)
def load_keyblob(self):
if self.keyblob_storage == KEYBLOB_LOCAL:
k = KeyfileKey(self.repository)
target = k.find_key()
with open(target, 'r') as fd:
self.keyblob = ''.join(fd.readlines()[1:])
elif self.keyblob_storage == KEYBLOB_REPO:
self.keyblob = self.repository.load_key().decode()
def store_keyblob(self, args):
if self.keyblob_storage == KEYBLOB_LOCAL:
k = KeyfileKey(self.repository)
try:
target = k.find_key()
except KeyfileNotFoundError:
target = k.get_new_target(args)
self.store_keyfile(target)
elif self.keyblob_storage == KEYBLOB_REPO:
self.repository.save_key(self.keyblob.encode('utf-8'))
def store_keyfile(self, target):
with open(target, 'w') as fd:
fd.write('%s %s\n' % (KeyfileKey.FILE_ID, bin_to_hex(self.repository.id)))
fd.write(self.keyblob)
if not self.keyblob.endswith('\n'):
fd.write('\n')
def export(self, path):
self.store_keyfile(path)
def export_paperkey(self, path):
def grouped(s):
ret = ''
i = 0
for ch in s:
if i and i % 6 == 0:
ret += ' '
ret += ch
i += 1
return ret
export = 'To restore key use borg key import --paper /path/to/repo\n\n'
binary = a2b_base64(self.keyblob)
export += 'BORG PAPER KEY v1\n'
lines = (len(binary) + 17) // 18
repoid = bin_to_hex(self.repository.id)[:18]
complete_checksum = sha256_truncated(binary, 12)
export += 'id: {0:d} / {1} / {2} - {3}\n'.format(lines,
grouped(repoid),
grouped(complete_checksum),
sha256_truncated((str(lines) + '/' + repoid + '/' + complete_checksum).encode('ascii'), 2))
idx = 0
while len(binary):
idx += 1
binline = binary[:18]
checksum = sha256_truncated(idx.to_bytes(2, byteorder='big') + binline, 2)
export += '{0:2d}: {1} - {2}\n'.format(idx, grouped(bin_to_hex(binline)), checksum)
binary = binary[18:]
if path:
with open(path, 'w') as fd:
fd.write(export)
else:
print(export)
def import_keyfile(self, args):
file_id = KeyfileKey.FILE_ID
first_line = file_id + ' ' + bin_to_hex(self.repository.id) + '\n'
with open(args.path, 'r') as fd:
file_first_line = fd.read(len(first_line))
if file_first_line != first_line:
if not file_first_line.startswith(file_id):
raise NotABorgKeyFile()
else:
raise RepoIdMismatch()
self.keyblob = fd.read()
self.store_keyblob(args)
def import_paperkey(self, args):
# imported here because it has global side effects
import readline
repoid = bin_to_hex(self.repository.id)[:18]
try:
while True: # used for repeating on overall checksum mismatch
# id line input
while True:
idline = input('id: ').replace(' ', '')
if idline == "":
if yes("Abort import? [yN]:"):
raise EOFError()
try:
(data, checksum) = idline.split('-')
except ValueError:
print("each line must contain exactly one '-', try again")
continue
try:
(id_lines, id_repoid, id_complete_checksum) = data.split('/')
except ValueError:
print("the id line must contain exactly three '/', try again")
if sha256_truncated(data.lower().encode('ascii'), 2) != checksum:
print('line checksum did not match, try same line again')
continue
try:
lines = int(id_lines)
except ValueError:
print('internal error while parsing length')
break
if repoid != id_repoid:
raise RepoIdMismatch()
result = b''
idx = 1
# body line input
while True:
inline = input('{0:2d}: '.format(idx))
inline = inline.replace(' ', '')
if inline == "":
if yes("Abort import? [yN]:"):
raise EOFError()
try:
(data, checksum) = inline.split('-')
except ValueError:
print("each line must contain exactly one '-', try again")
continue
try:
part = unhexlify(data)
except binascii.Error:
print("only characters 0-9 and a-f and '-' are valid, try again")
continue
if sha256_truncated(idx.to_bytes(2, byteorder='big') + part, 2) != checksum:
print('line checksum did not match, try line {0} again'.format(idx))
continue
result += part
if idx == lines:
break
idx += 1
if sha256_truncated(result, 12) != id_complete_checksum:
print('The overall checksum did not match, retry or enter a blank line to abort.')
continue
self.keyblob = '\n'.join(textwrap.wrap(b2a_base64(result).decode('ascii'))) + '\n'
self.store_keyblob(args)
break
except EOFError:
print('\n - aborted')
return
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