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reversible hash function !!! plzz help ..

da_comp_guyda_comp_guy Member Posts: 37
hello guys ... i'm in lookout for a two way or a reversible cryptographic/hash function. well, to be precise i'm in lookout for such an algorithm which'll give me a fixed length output, which can be reversed back to the original text when i want it to (lets say i have my password hardcoded) . plzzzz help .... its pretty urgent !! [:(]
"[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]

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  • zibadianzibadian Member Posts: 6,349
    : hello guys ... i'm in lookout for a two way or a reversible
    : cryptographic/hash function. well, to be precise i'm in lookout for
    : such an algorithm which'll give me a fixed length output, which can
    : be reversed back to the original text when i want it to (lets say i
    : have my password hardcoded) . plzzzz help .... its pretty urgent !!
    : [:(]
    : "[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]

    One of the most important properties of hash functions is that they are not reversible.
    You might want to check out a blockcipher. For most blockciphers the output length is equal to the input length.
    Placing a hardcoded "readable" password in your code is a very serious security design flaw. Using reverse-engineering someone will be able to find the decryption code and then easily read the password.
  • da_comp_guyda_comp_guy Member Posts: 37
    hmmm... i c ..! i'll correct that...! thanx a lot !
    "[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]
  • da_comp_guyda_comp_guy Member Posts: 37
    but yet again ... i think i've hrd something abt "two way" hash functions. what are they then ?
    "[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]
  • zibadianzibadian Member Posts: 6,349
    : but yet again ... i think i've hrd something abt "two way" hash
    : functions. what are they then ?
    : "[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]

    Hash functions are mathematical equations, which can only be done one way. A very simple (but very poor) hash function is the sum. If I told you that the sum of a series of numbers equals 4620225432, then you cannot tell me which numbers they are. You can tell me several other numbers equaling that sum, but not directly the numbers I had in mind. This is called a collision.
    Cryptographically strong hash functions use the same principle, but their algorithm makes sure that there are as few collisions as possible. A second property of hash functions is that the value changes radically if even 1 bit of the original data is changed.
    For more info on hash functions see: http://en.wikipedia.org/wiki/Hash_function
  • da_comp_guyda_comp_guy Member Posts: 37
    yes i knw abt that and the avalanche effect too :)
    i dunno... i had a notion somewhere hidden inside in my mind.. abt some "reversible" hash functions.
    any how i guess i was wrong.
    thanx again ... :)

    "[b]The[blue] GEEK[/blue] Shall Inherit The Earth" ;-) [/b]
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