1  # The MIT License (MIT)
 2  #
 3  # Copyright (c) 2020 Jim Bennett
 4  #
 5  # Permission is hereby granted, free of charge, to any person obtaining a copy
 6  # of this software and associated documentation files (the "Software"), to deal
 7  # in the Software without restriction, including without limitation the rights
 8  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9  # copies of the Software, and to permit persons to whom the Software is
10  # furnished to do so, subject to the following conditions:
11  #
12  # The above copyright notice and this permission notice shall be included in
13  # all copies or substantial portions of the Software.
14  #
15  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21  # THE SOFTWARE.
22  """
23  `base64`
24  ================================================================================
25  
26  RFC 3548: Base64 Data Encodings
27  
28  
29  * Author(s): Jim Bennett
30  
31  Implementation Notes
32  --------------------
33  
34  **Software and Dependencies:**
35  
36  * Adafruit CircuitPython firmware for the supported boards:
37    https://github.com/adafruit/circuitpython/releases
38  
39  """
40  
41  import adafruit_binascii as binascii
42  
43  __all__ = ["b64encode", "b64decode"]
44  
45  
46  def _bytes_from_decode_data(data: str):
47      try:
48          return data.encode("ascii")
49      except:
50          raise ValueError("string argument should contain only ASCII characters")
51  
52  
53  def b64encode(toencode: bytes) -> bytes:
54      """Encode a byte string using Base64.
55  
56      toencode is the byte string to encode.  Optional altchars must be a byte
57      string of length 2 which specifies an alternative alphabet for the
58      '+' and '/' characters.  This allows an application to
59      e.g. generate url or filesystem safe Base64 strings.
60  
61      The encoded byte string is returned.
62      """
63      # Strip off the trailing newline
64      return binascii.b2a_base64(toencode)[:-1]
65  
66  
67  def b64decode(todecode: str) -> bytes:
68      """Decode a Base64 encoded byte string.
69  
70      todecode is the byte string to decode.  Optional altchars must be a
71      string of length 2 which specifies the alternative alphabet used
72      instead of the '+' and '/' characters.
73  
74      The decoded string is returned.  A binascii.Error is raised if todecode is
75      incorrectly padded.
76  
77      If validate is False (the default), non-base64-alphabet characters are
78      discarded prior to the padding check.  If validate is True,
79      non-base64-alphabet characters in the input result in a binascii.Error.
80      """
81      return binascii.a2b_base64(_bytes_from_decode_data(todecode))