68 lines
2.1 KiB
Python
68 lines
2.1 KiB
Python
#!/usr/bin/env python
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# Copyright 2011 OpenStack Foundation
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Routines for URL-safe encrypting/decrypting
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"""
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import base64
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from Crypto.Cipher import AES
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from Crypto import Random
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from Crypto.Random import random
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def urlsafe_encrypt(key, plaintext, blocksize=16):
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"""
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Encrypts plaintext. Resulting ciphertext will contain URL-safe characters
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:param key: AES secret key
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:param plaintext: Input text to be encrypted
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:param blocksize: Non-zero integer multiple of AES blocksize in bytes (16)
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:returns : Resulting ciphertext
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"""
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def pad(text):
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"""
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Pads text to be encrypted
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"""
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pad_length = (blocksize - len(text) % blocksize)
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sr = random.StrongRandom()
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pad = ''.join(chr(sr.randint(1, 0xFF)) for i in range(pad_length - 1))
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# We use chr(0) as a delimiter between text and padding
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return text + chr(0) + pad
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# random initial 16 bytes for CBC
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init_vector = Random.get_random_bytes(16)
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cypher = AES.new(key, AES.MODE_CBC, init_vector)
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padded = cypher.encrypt(pad(str(plaintext)))
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return base64.urlsafe_b64encode(init_vector + padded)
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def urlsafe_decrypt(key, ciphertext):
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"""
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Decrypts URL-safe base64 encoded ciphertext
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:param key: AES secret key
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:param ciphertext: The encrypted text to decrypt
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:returns : Resulting plaintext
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"""
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# Cast from unicode
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ciphertext = base64.urlsafe_b64decode(str(ciphertext))
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cypher = AES.new(key, AES.MODE_CBC, ciphertext[:16])
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padded = cypher.decrypt(ciphertext[16:])
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return padded[:padded.rfind(chr(0))]
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