algorithm - How is one way hashing possible? -

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i wondering, how 1 way hashing possible? how can encode string in 1 direction , not other? if reverse algorithm, can't decode md5? before, me, way possible have generate random answer instead of using algorithm. hashes same way every time. please explain me.

if "reverse" algorithm, cannot original string back, because there more possible strings possible hash codes.

think of algorithm has result 64-bit integers. there 2^64 = (2^8)^8 = 256^8 possible such numbers.

but means, if there more 256^8 possible strings, there must 2 strings hash same value (this called the pigeonhole principle). since there more strings @ length 9 (256^9 such strings), fact can hash value, not guarantee can "go back".


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