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9316e7c014
* flake8 --max-line-length=88
* fixup! Format Python code with psf/black push
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
90 lines
2.4 KiB
Python
90 lines
2.4 KiB
Python
def encode_base64(text):
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r"""
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>>> encode_base64('WELCOME to base64 encoding 😁')
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'V0VMQ09NRSB0byBiYXNlNjQgZW5jb2Rpbmcg8J+YgQ=='
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>>> encode_base64('AÅᐃ𐀏🤓')
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'QcOF4ZCD8JCAj/CfpJM='
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>>> encode_base64('A'*60)
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'QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB\r\nQUFB'
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"""
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base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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byte_text = bytes(text, "utf-8") # put text in bytes for unicode support
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r = "" # the result
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c = -len(byte_text) % 3 # the length of padding
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p = "=" * c # the padding
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s = byte_text + b"\x00" * c # the text to encode
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i = 0
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while i < len(s):
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if i > 0 and ((i / 3 * 4) % 76) == 0:
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r = r + "\r\n" # for unix newline, put "\n"
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n = (s[i] << 16) + (s[i + 1] << 8) + s[i + 2]
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n1 = (n >> 18) & 63
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n2 = (n >> 12) & 63
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n3 = (n >> 6) & 63
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n4 = n & 63
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r += base64_chars[n1] + base64_chars[n2] + base64_chars[n3] + base64_chars[n4]
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i += 3
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return r[0 : len(r) - len(p)] + p
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def decode_base64(text):
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r"""
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>>> decode_base64('V0VMQ09NRSB0byBiYXNlNjQgZW5jb2Rpbmcg8J+YgQ==')
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'WELCOME to base64 encoding 😁'
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>>> decode_base64('QcOF4ZCD8JCAj/CfpJM=')
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'AÅᐃ𐀏🤓'
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>>> decode_base64("QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUF"
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... "BQUFBQUFBQUFB\r\nQUFB")
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'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA'
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"""
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base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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s = ""
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for i in text:
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if i in base64_chars:
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s += i
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c = ""
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else:
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if i == "=":
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c += "="
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p = ""
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if c == "=":
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p = "A"
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else:
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if c == "==":
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p = "AA"
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r = b""
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s = s + p
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i = 0
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while i < len(s):
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n = (
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(base64_chars.index(s[i]) << 18)
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+ (base64_chars.index(s[i + 1]) << 12)
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+ (base64_chars.index(s[i + 2]) << 6)
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+ base64_chars.index(s[i + 3])
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)
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r += bytes([(n >> 16) & 255]) + bytes([(n >> 8) & 255]) + bytes([n & 255])
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i += 4
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return str(r[0 : len(r) - len(p)], "utf-8")
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def main():
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print(encode_base64("WELCOME to base64 encoding 😁"))
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print(decode_base64(encode_base64("WELCOME to base64 encoding 😁")))
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if __name__ == "__main__":
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main()
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