Python/ciphers/base32.py

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"""
Base32 encoding and decoding
https://en.wikipedia.org/wiki/Base32
"""
B32_CHARSET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
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def base32_encode(data: bytes) -> bytes:
"""
>>> base32_encode(b"Hello World!")
b'JBSWY3DPEBLW64TMMQQQ===='
>>> base32_encode(b"123456")
b'GEZDGNBVGY======'
>>> base32_encode(b"some long complex string")
b'ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY='
"""
binary_data = "".join(bin(ord(d))[2:].zfill(8) for d in data.decode("utf-8"))
binary_data = binary_data.ljust(5 * ((len(binary_data) // 5) + 1), "0")
b32_chunks = map("".join, zip(*[iter(binary_data)] * 5))
b32_result = "".join(B32_CHARSET[int(chunk, 2)] for chunk in b32_chunks)
return bytes(b32_result.ljust(8 * ((len(b32_result) // 8) + 1), "="), "utf-8")
def base32_decode(data: bytes) -> bytes:
"""
>>> base32_decode(b'JBSWY3DPEBLW64TMMQQQ====')
b'Hello World!'
>>> base32_decode(b'GEZDGNBVGY======')
b'123456'
>>> base32_decode(b'ONXW2ZJANRXW4ZZAMNXW24DMMV4CA43UOJUW4ZY=')
b'some long complex string'
"""
binary_chunks = "".join(
bin(B32_CHARSET.index(_d))[2:].zfill(5)
for _d in data.decode("utf-8").strip("=")
)
binary_data = list(map("".join, zip(*[iter(binary_chunks)] * 8)))
return bytes("".join([chr(int(_d, 2)) for _d in binary_data]), "utf-8")
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if __name__ == "__main__":
import doctest
doctest.testmod()