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POHow to rearrange 36-bit character string using Pseudo-Random Number Generator (PRNG)
 

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  1. POHow to rearrange 36-bit character string using Pseudo-Random Number Generator (PRNG)
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    <p>I have made a program to encode and decode long URL's. Encode will take n characters and outputs a 36-bit character string. Decode will take a 36-bit character string and output a long character string.</p> <pre><code>print(decode(encode(1234567890))) '1234567890' </code></pre> <p>So basically, something that will randomize a 36-bit string and it's decode opposite. Is there a way using a pseudo random number generator to make the properties of a seeded PRNG reversible and use some invariant property of the numbers to seed the PRNG.</p> <p>I know bits and pieces of this code, these might help.</p> <pre><code>def ls1b( x ): """Return least significant bit of x that is a one. (Assume x &gt;= 0.)""" return x &amp; -x </code></pre> <p>And</p> <pre><code>def bitson( x ): """Return the number of one bits in x. (Assume x &gt;= 0.)""" count = 0 while x != 0: x &amp;= ~ls1b( x ) count += 1 return count </code></pre> <p>Here is my encode and decode.</p> <pre><code>def token (n): if n &lt; 10: return chr( ord( '0' ) + (n) ) if n in range (10, 36): return chr( ord( 'A' ) - 10 + (n)) if n in range (37, 62): return chr( ord( 'a' ) - 36 + (n)) if n is 62: return '-' if n is 63: return '+' def encode (n): a = n // 1 % 64 b = n // 64 % 64 c = n // 64 ** 2 % 64 d = n // 64 ** 3 % 64 e = n // 64 ** 4 % 64 f = n // 64 ** 5 % 64 return (token(a) + token(b) + token(c) + token(d) + token(e) + token(f)) def tokend (d): x = ord(d) if 48 &lt;= x &lt;= 57: return x - ord('0') if 65 &lt;= x &lt;= 90: return x - ord('A') + 10 if 97 &lt;= x &lt;= 122: return x - ord('a') + 36 if x is 43: return ('62') if x is 45: return ('63') def decode(code, base=64): if base&gt;64: return 'error: too few symbols' code=str(code) o=0 e=0 for i in code: o=o+detoken(i)*base**e e=e+1 while len(str(o))&lt;6: o='0'+str(o) return o </code></pre>
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      1. POHow to rearrange 36-bit character string using Pseudo-Random Number Generator (PRNG)
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    1. COAre you trying to shorten the URL like tinyurl? Also, why decode outputs a "36-bit" but encode takes "6 characters"?
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      1. POHow to rearrange 36-bit character string using Pseudo-Random Number Generator (PRNG)
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    2. COIf I understand correctly, you are trying to do a reversible hash function, right? Or maybe something like compressing function?
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      1. POHow to rearrange 36-bit character string using Pseudo-Random Number Generator (PRNG)
      1. USmatan7890
    3. COI have already been successful shortening URL's. And, sorry, I didn't mean to say it only encodes 6 characters. It can encode any length of characters. What I am trying to do, is to randomize the outputs of both encode and decode operations.
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