2020-06-14 07:49:39 +00:00
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"""
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Adler-32 is a checksum algorithm which was invented by Mark Adler in 1995.
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2020-06-16 08:09:19 +00:00
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Compared to a cyclic redundancy check of the same length, it trades reliability for
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speed (preferring the latter).
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Adler-32 is more reliable than Fletcher-16, and slightly less reliable than
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Fletcher-32.[2]
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2020-06-14 07:49:39 +00:00
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source: https://en.wikipedia.org/wiki/Adler-32
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"""
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def adler32(plain_text: str) -> str:
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"""
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Function implements adler-32 hash.
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Itterates and evaluates new value for each character
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>>> adler32('Algorithms')
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363791387
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>>> adler32('go adler em all')
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708642122
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"""
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MOD_ADLER = 65521
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a = 1
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b = 0
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for plain_chr in plain_text:
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a = (a + ord(plain_chr)) % MOD_ADLER
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b = (b + a) % MOD_ADLER
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return (b << 16) | a
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