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# Copyright 2020 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS-IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""A command-line utility for testing DAEAD-primitives.
It requires 5 arguments:
keyset-file: name of the file with the keyset to be used
for encrypting/decrypting
operation: the actual DeterminisiticAead-operation, i.e.
"encryptdeterministically" or "decryptdeterministically"
input-file: name of the file that contains plaintext to be encrypted or the
encrypted text to be decrypted
associated-data-file: name of the file that contains
associated-data used for encryption/decryption
output-file: name of the output file for the resulting encryptedtext
"""
from __future__ import absolute_import
from __future__ import division
# Placeholder for import for type annotations
from __future__ import print_function
# Special imports
from absl import app
from absl import flags
from absl import logging
import tink
from tink import cleartext_keyset_handle
from tink import daead
FLAGS = flags.FLAGS
def read_keyset(keyset_filename):
"""Load a keyset from a file.
Args:
keyset_filename: A path to a keyset file
Returns:
A KeysetHandle of the file's keyset
Raises:
TinkError: if the file is not valid
IOError: if the file does not exist
"""
with open(keyset_filename, 'rb') as keyset_file:
text = keyset_file.read()
keyset = cleartext_keyset_handle.read(
tink.BinaryKeysetReader(text))
return keyset
def main(argv):
if len(argv) != 6:
raise app.UsageError(
'Expected 5 arguments, got %d.\n'
'Usage: %s keyset-file operation input-file associated-data-file'
'output-file' % (len(argv) - 1, argv[0]))
keyset_filename = argv[1]
operation = argv[2]
input_filename = argv[3]
associated_data_filename = argv[4]
output_filename = argv[5]
logging.info(
'Using keyset from file %s to DAEAD-%s file %s with associated data '
'from file %s.\nThe resulting output will be written to file %s',
keyset_filename, operation, input_filename, associated_data_filename,
output_filename)
# Initialise Tink
try:
daead.register()
except tink.TinkError as e:
logging.error('Error initialising Tink: %s', e)
return 1
# Read the keyset into keyset_handle
try:
keyset_handle = read_keyset(keyset_filename)
except tink.TinkError as e:
logging.error('Error reading key: %s', e)
return 1
# Get the primitive
try:
cipher = keyset_handle.primitive(daead.DeterministicAead)
except tink.TinkError as e:
logging.error('Error creating primitive: %s', e)
return 1
# Read the input files
with open(input_filename, 'rb') as input_file:
input_data = input_file.read()
with open(associated_data_filename, 'rb') as associated_data_file:
aad = associated_data_file.read()
# Compute the output
if operation.lower() == 'encryptdeterministically':
try:
output_data = cipher.encrypt_deterministically(input_data, aad)
except tink.TinkError as e:
logging.error('Error encrypting the input: %s', e)
return 1
elif operation.lower() == 'decryptdeterministically':
try:
output_data = cipher.decrypt_deterministically(input_data, aad)
except tink.TinkError as e:
logging.error('Error decrypting the input: %s', e)
return 1
else:
logging.error(
'Did not recognise operation %s.\n'
'Expected either "encrypt" or "decrypt"', operation)
return 1
with open(output_filename, 'wb') as output_file:
output_file.write(output_data)
logging.info('All done.')
if __name__ == '__main__':
app.run(main)