Then the problem becomes easy, because you can solve each round incrementally, instead of having to guess the full secret correctly all-at-once.What if instead of sum, you were concatenating hashes? You tag the question as JS - but I would certainly not use JS for an efficient, cluster-friendly cracker. To search faster, you should go as close to the metal as possible (for example, use SIMD instructions to calculate several hashes at the same time in the CPU) and/or use as many machines as possible computing hashes in parallel. Building an efficient brute-force cracker will be a significant hurdle but in general, the only way to brute-force faster is either to reduce the search-space (see above) or search faster.If you suspect that they may be using the domain, that's a very large chunk of search-space that you no longer need to look into (16 characters, and 17 if you include the sign). In particular, since you are looking for an e-mail address, it only makes sense to look for valid addresses - greatly reducing the search-space. Any information that reduces the search-space will make the process much, much faster.Therefore, brute force can work, because if you get the right result, you (with overwhelming probability) have the right email. So you can simply build strings of the expected length until one hashes to the expected result. It is astronomically unlikely that, for a random input, the result of following their procedure of summing up hashes-of-altered-substrings will result in the desired output.The average MD5 is therefore between 2^128 - 1 (all bits on) and 0, with an expected average of 2^127 so if your input is in the range 14*2^127 to 16*2^127, you should expect around 16 characters of e-mail to guess. MD5 hashes are 128-bit long, and for any given input you expect roughly half of those bits to be on and half to be off. You can estimate the length of the secret email based on the provided hash (which is a sum of length(email)-1 hashes)._ clearly )Ģ-Don't try to decode or reverse-engineer md5 hash to solve the problem. This is the step that I can't proceed.And also it says in notification =>ġ-The mail address can contain numbers, all english letters and special characters: +. Using the information above, solve the hash, find the hidden email address and send your project to that address. ![]() Each substring is hashed with the formula: md5(md5(your_email_address) + x + md5(x)) and then added all together as the hash. ![]() We'll refer this substrings as "x" in the following clause. We have splitted the hidden email address into multiple substrings, starting with first two letters and increasing by two letters in each iteration.
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