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i want to have a string whose MD5 code is same as the original string has,

i mean i wants a tools that takes MD5 code and gives multiple possible strings which have the same MD5 code .

is there any tool exists???

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3 Answers 3

up vote 2 down vote accepted

While there have been some reported weaknesses to MD5 that suggest it is possible to have the same hash for two different inputs, generally speaking, the whole point of MD5 is to prevent what you are asking for. Hashing algorithms like MD5 are designed so that each input will have a unique output (within certain mathematical bounds defined by the particular algorithm).

In any case, no such tool exists.

EDIT: Note that other answers are popping up that are saying such tools exist, although I don't think they are the same thing the original post is asking for. There certainly are tools that will brute-force MD5 and other hashing algorithms for the purpose of finding out the original value, but I stand by my statement that there are no such tools that are designed for the purpose of locating hash collisions (i.e. two different strings that will result in the same hash).

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That's not a 100% percent true...there's still the brute-force approach, and there are plenty of tools for that. And he's just asking for a tool that returns possible strings, he never said in what timespan. –  Bobby Jun 24 '10 at 11:17
    
The tools that brute force an MD5 hash are generally targeted towards figuring out the original string that the hash was generated from. Of course there is no way to know if the tool generated the original string or a successful hash collision, but I am quite certain that there are no tools currently in existence that will purposefully attempt to generate hash collisions, even for MD5, which has been weakened to the point that generating hash collisions has been demonstrated by cryptography researchers. –  Jed Daniels Jun 24 '10 at 11:30
    
True. I reread the question and you're right, sry. –  Bobby Jun 24 '10 at 11:33
    
well, all the brute force tools are looking for the first match. if you do not stop searching after the first match you have what OP asks for. of cause it is extremely unlikely that the tool will find something else in a reasonable timespan, but .. thats not your / my problem, is it? –  akira Jun 24 '10 at 12:25
    
@akira I'm not aware of any tools that will continue searching after a match. Are you? –  Jed Daniels Jun 24 '10 at 16:49

There are several such database available online. It's in fact just a big database that has been generated using dictionary of user input to generate the corresponding MD5 hash. That stored will give you a database in which can look up existing words.

So if your MD5 hash is generated from a common or dictionary phrase, good chance you'll find it.

Check out http://tools.benramsey.com/md5

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yes, such tools exist: they have to guess the original string, pipe it through md5 (or other algorithms) and compare the result with the reference checksum, which is called brute-force and can take some time.

'hashcat' is one of these tools.

normally such hash-algorithms are designed in a way that it is pretty hard to get duplicates (so called hash-collisions) and i would be surprised if you find one :) but nevertheless, tools trying to get at least one original stream of bytes exist.

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