linq - Performance tuning C# permutations and SHA1 code -

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although university assignment (homework) i've come best solution think of. achieve full marks code matches question, specially allowed develop in c# rather else using java, kind of "yeh, show c# can do" challenge ;-)

the question was:

create program find password of sha1 hash using brute force technique, assuming passwords 6 characters long , can contain lower-case a-z , 0-9.

i created linq query , after have possible combinations need run them through sha1 hash , compare provided password hash.

i created code:

public static string bruteforcehash(string hash)         {                  var results = c0 in enumerable.range(0, 36)                               c1 in enumerable.range(0, 36)                               c2 in enumerable.range(0, 36)                               c3 in enumerable.range(0, 36)                               c4 in enumerable.range(0, 36)                               c5 in enumerable.range(0, 36)                               select new string(                                   new[]                                 {                                     characters[c0],                                     characters[c1],                                     characters[c2],                                     characters[c3],                                     characters[c4],                                     characters[c5],                                 }                                   );                  string found = null;                 parallel.foreach(results, (result, loopstate, a) =>                                               {                                                   string hashed = sha1(result, encoding.default);                                                    if (hashed == hash)                                                   {                                                       found = result;                                                       loopstate.break();                                                   }                                               });                  if (found != null)                 {                     return found;                 }              return "not found.";         }

now real problem solved easy passwords ("aaaaaa" instant) takes longer further password away "aaaaaa".

i hope provide pointers on how increase performance.

if happy implementation run code performance profiler yourkit or dottrace can @ hot spot in code , @ tuning there. nice when using syntacticly sugared code linq, way can feel whats going on under hood too...


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