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* Added base64 to binary conversion. * updating DIRECTORY.md --------- Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: cclauss <cclauss@users.noreply.github.com>
113 lines
2.5 KiB
Python
113 lines
2.5 KiB
Python
"""
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* Author: Siddharth Singh (https://github.com/coolsidd)
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* Description: Convert a binary string to Base64.
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References for better understanding:
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https://en.wikipedia.org/wiki/Base64
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"""
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B64_TO_BITS = {
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"A": "000000",
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"B": "000001",
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"C": "000010",
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"D": "000011",
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"E": "000100",
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"F": "000101",
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"G": "000110",
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"H": "000111",
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"I": "001000",
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"J": "001001",
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"K": "001010",
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"L": "001011",
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"M": "001100",
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"N": "001101",
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"O": "001110",
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"P": "001111",
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"Q": "010000",
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"R": "010001",
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"S": "010010",
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"T": "010011",
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"U": "010100",
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"V": "010101",
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"W": "010110",
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"X": "010111",
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"Y": "011000",
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"Z": "011001",
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"a": "011010",
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"b": "011011",
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"c": "011100",
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"d": "011101",
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"e": "011110",
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"f": "011111",
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"g": "100000",
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"h": "100001",
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"i": "100010",
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"j": "100011",
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"k": "100100",
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"l": "100101",
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"m": "100110",
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"n": "100111",
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"o": "101000",
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"p": "101001",
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"q": "101010",
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"r": "101011",
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"s": "101100",
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"t": "101101",
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"u": "101110",
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"v": "101111",
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"w": "110000",
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"x": "110001",
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"y": "110010",
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"z": "110011",
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"0": "110100",
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"1": "110101",
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"2": "110110",
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"3": "110111",
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"4": "111000",
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"5": "111001",
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"6": "111010",
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"7": "111011",
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"8": "111100",
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"9": "111101",
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"+": "111110",
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"/": "111111",
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}
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def base64_to_bin(base64_str: str) -> str:
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"""Convert a base64 value to its binary equivalent.
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>>> base64_to_bin("ABC")
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'000000000001000010'
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>>> base64_to_bin(" -abc ")
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'-011010011011011100'
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>>> base64_to_bin(" a-bc ")
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Traceback (most recent call last):
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...
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ValueError: Invalid base64 string. Invalid char - at pos 1
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>>> base64_to_bin("")
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Traceback (most recent call last):
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...
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ValueError: Empty string was passed to the function
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"""
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b64_str = str(base64_str).strip()
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if not b64_str:
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raise ValueError("Empty string was passed to the function")
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is_negative = b64_str[0] == "-"
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if is_negative:
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b64_str = b64_str[1:]
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bin_str = ""
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for i, x in enumerate(b64_str):
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if x not in B64_TO_BITS:
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exception_message = f"Invalid base64 string. Invalid char {x} at pos {i}"
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raise ValueError(exception_message)
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bin_str += B64_TO_BITS[x]
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if is_negative:
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bin_str = "-" + bin_str
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return bin_str
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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