Decrypt md5
Solved/Closed43 answers
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BobinoursMD5 is a non-reversible algorithm.
To use this kind of function, you need to compare 2 strings encrypted with MD5 and see if they are equal. You can then infer the original string.
-= Bobinours =- -
cornelius62Here’s a decent site to decrypt MD5
http://hash-decrypter.com -
anima-webmsIt's possible at the university, the professor gave us an MD5 and we had to decrypt it, it took 6 hours of work, so it is possible.
MD5 to find: b747f94da7fbbc5def00394f21ce6822
Word found: Euclid
So it is entirely possible to find this kind of thing.
But it is difficult to do so!
I will not reveal the trick because it might be used for malicious purposes.-
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fiddy ContributorI will not reveal the trick because it might be used for the wrong purposes.
There is no magic trick. Just brute force, or more subtly, a rainbow table. However, you will only find simple words (like Euclid...).
Hence the use of salt before hashing a password.
By the way, I can give you an MD5, and we’ll see that you won’t take 6 hours to find it ^^. -
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chatoune1Can someone help me decode this, please?
ac83c6cd2f06e9cf64a0756453489f26-
Nabla's ContributorPlease review the post, thank you...
https://forums.commentcamarche.net/forum/affich-101168-decrypter-md5?page=2#84
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davitz38But you can use online tools (they use large databases) like this one: http://www.stringfunction.com/md5-decrypter.html
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robertHello everyone
For searching the cleartext of an MD5 hash, I recommend http://hash.db.hk. It combines a database search with brute force using GPUs (Cuda).
The results are impressive.
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chewieIt's normal that MD5 hasn't been cracked yet.
The algorithm is related to the machine's registers and their use in a specific order...
So, already, to be able to crack MD5, you need to be on the machine so that its signature can be identified... and even then, given that the generation doesn't necessarily go through the same registers, you won't get the same result if you enter the same password twice.
In short, if you want to know how it works, you just have to go to www.ietf.org (Internet Engineering Task Force).
You can look in the RFCs (memos describing the standards for how things related to the net have worked since 1969...).
There is an RFC that describes the logical functioning of MD5.
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There is an RFC for everything...-
blux ModeratorYou need to be on the machine for your signature to be identified...
And even then, given that the generation doesn’t necessarily go through the same registers, you won’t get the same result if you enter the same password twice.
False! An MD5 calculation is the same regardless of the machine! Otherwise, I don't see the point...
And we have already repeated that we don't break MD5; we can just find a sequence of bits that gives the MD5 we are looking for...
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A+ Blux"Rude people dare anything. That's how you recognize them"
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fiddy Contributor@bluxAnd I would even add that for the moment we can only generate two messages with the same hash (collision) and find a weak MD5 through rainbow tables.
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blux Moderator
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fiddy Contributor@bluxYes, that is possible. But for now, the best algorithms capable of generating collisions are only for two. For three, it would take too much time ^^.
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fiddy ContributorIndeed, the collision is quite different from the second pre-image attack: http://fiddy.free.fr/...
Best regards
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Xortax@sebsauvageThank you all for the details, it's really too bad that I can't know what is hidden behind:
e088da6d7bf99aa251543ede28c6973d.. sniff
But thank you very much...... -
le père
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sebsauvage Moderator@XortaxYes, it's heavy right now... read what I provided as responses.
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sebsauvage ModeratorYou don't talk much about MD5 collisions, which allow for a string that returns the desired MD5 code ...
Currently, nothing allows obtaining collisions for a specific MD5.
The only thing we can do is calculate strings that cause collisions, but you do not control the resulting MD5, and the source strings contain a block of several dozen bytes of random appearance.
It is therefore still not possible to forge a document or a string having a specific MD5, except through brute force.-
Nabla's Contributorok. I think this was done by brute force then: https://www.clubic.com/actualite-248742-securite-200-ps3-generer-faux-certificats-ssl.html (given the number of PS3s) ...
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sebsauvage Moderator@Nabla'sThe Clubic article is full of errors. First of all, they present MD5 as an encryption algorithm :-/
They didn't break MD5, but what they did was clever:
Generally, strings with the same MD5 look random.
It's "easy" to find strings with the same MD5, but much more difficult to generate, for example, two JPG images with the same MD5.
They used the computing power of PS3s to successfully generate 2 SSL certificates with the same MD5.
They had the first one signed by RapidSSL, which is a PKI.
RapidSSL then returned the signed certificate to them. However, when you "sign" a document, you’re actually not signing the document but the MD5 of the document.
Once they retrieved the RapidSSL signature, they only had to substitute it with the other certificate they generated. Thus, they obtained a makeshift certificate whose MD5 is signed by RapidSSL.
It's clever, but it still doesn't allow them to generate a document with a precise MD5. -
Nabla's Contributor@sebsauvageSure, thanks for the clarification...
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Nabla's ContributorIt's nice of you to talk to us about rainbow tables, and even to have provided some websites, but you don't talk much about MD5 collisions, which allow for a string that returns the desired MD5 code...
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sebsauvage ModeratorYeah, well, apparently you didn't get it.
Xortax: The MD5 works as follows:
You give it a sequence of bytes of any length, and it outputs a 128-bit string.
Therefore, it can't be "decrypted", otherwise you could compress a DVD into 128 bits.
The only thing you can do to find out which string corresponds to an MD5 is to create all possible character strings, calculate their MD5 and compare with the MD5 you're looking for.
However, some enthusiasts have created gigantic databases of pre-calculated MD5s.
That's the link I provided: by chance, the MD5 you're searching for is present in that database, and the string corresponding to your MD5 is "????"
Okay? -
le pèreHello
Sebsauvage, I feel like xortax couldn't decipher your response :D -
fiddy ContributorDecipher=not related to numbers. (+ harder to explain)
With numbers, no. But we decipher what has been encrypted (unlike MD5 which is a hashing function and not encryption). And be careful not to confuse decrypt and decipher ;-))).
Otherwise, salting consists of concatenating a piece of data with the password (or other) to hash. The result is a hash that will not be in rainbow tables. http://en.wikipedia.org/wiki/Salt_(cryptography)
Best regards
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arth ContributorWell, you know when you cook, sometimes it's better with salt, well, it's the same here ...
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fiddy ContributorI think it’s good if others don't say stupid things.
Don't bother, there’s no systematic way to calculate the original message. MD5 should no longer be used because the generation of collisions has become very fast due to the efficiency of algorithms and can therefore be exploited to break systems that rely on MD5 ( http://fiddy.free.fr/... )
But there’s no attack on MD5 for the first pre-image. The most effective method is the use of rainbow tables. And that's precisely why you should always use a salt before hashing a password.
Try to find the message: 15007ce8d8be1b65c56421a6a498b7e4
And I’ll even give you a hint because I’m nice, the salt I added at the end is: #samushack
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BobinoursI like Wikipedia too ;-)
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-= Bobinours =- -
lami20j ModeratorHello,
No need to shout. And a greeting doesn't hurt.
Say the result for d6aa97d33d459ea3670056e737c99a3d
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106485010510997108 -
fiddy ContributorYes, but you still agree with me that what man has created, he can also undo...
Except when it comes to an exact science like mathematics ;-).
The hash function is irreversible. Moreover, there is a loss of information. So, you can't retrieve the original message.
I agree with you, it must be hard...but there’s always a trick...right?
Yes, there are tricks like brute force, dictionary attacks, or the use of rainbow tables. The principle is to hash the message. If the hash equals the sought hash, then we have a possible candidate for the solution. But if the message is complex, it won't be in a dictionary, and brute force will take too long. That’s why hash functions are still widely used.
This doesn't mean that MD5 is secure though. Given that it's possible to find collisions, certain security measures can be compromised.
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blux Moderator@thomasno chance of recovering a single one... you either find the original message in its entirety or you don't...
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See you Blux"Fools dare everything. It's even how we recognize them"
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fiddy Contributor@bluxyou find the original message in full or you don't find it...
Correction: You find ONE possible original message in full or you don't find any.
No hard feelings ;-)).
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blux Moderator
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loupiusWell, this is really a topic that interests a lot of people: cracking the secret of a password or a text...
I'm not like fiddy, a specialist, but I have a few basic notions of combinatorial analysis.
So, what is md5: it’s 128 bits that is obtained from a string of characters (understood in the broad sense, a text of 100...000 characters is a string of characters).
Here’s why, regardless of the reliability of the md5 hash, it is almost impossible to be sure of the original string.
128 bits -> 2^128 which is only 3.4 * 10^38 possibilities.
For a text made up of 72 possible characters (26 uppercase, 26 lowercase, 10 digits, and 10 punctuations); if the text is:
- 10 characters -> 72^10 which is 3.4 * 10^18 possibilities (10^18 = 1 quintillion = 1 billion of billions).
- 20 characters -> 72^20 which is 1.4 * 10^37 possibilities; we can consider (assuming no duplicates) that each string may correspond to an md5 'code',
- 21 characters -> 72^21 which is 1 * 10^39 possibilities, there are necessarily duplicates.... thus impossibility of being sure of the original message.
- 1000 characters (about half a page) -> 72^1000 which is 2.2 * 10^1857, there will necessarily be (assuming an average distribution of the inevitable duplicates) -> (2.2 * 10^1857) / (3.4 * 10^38) which is 6.3 * 10^1818 texts of 1000 characters corresponding to an md5 'code'; one could say that it is almost impossible to have a correspondence table.
Therefore, if the string is very short (but already for 10 characters, you already need a table of 34 billion gigabytes), adding a 'salt' string is a satisfactory method and, on the other hand, using twisted characters in a password prevents a solution from being found in ridiculously small dictionaries.
Hoping I haven’t made any mistakes in my calculations, I wish everyone good reflection.-
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BobinoursMaths made me want to go further. It seems to me that the results don't match reality. Indeed, in your example you use 72 different characters, whereas just with those that I can easily access on my keyboard, I reach 132 characters (56 lowercase/uppercase letters + 10 digits + 15 accents + 51 special and punctuation characters), but I imagine that at least the 256 characters of extended ASCII are supported by MD5.
This gives for 10 characters:
256^10 = 1.2 x 10^24
Instead of:
72^10 = 3.4 x 10^18
It only takes 16 characters to obtain:
256^16 => 3.4 x 10^39
Which gives:
(3.4*10^39)/(3.4*10^38) or on average 10 different words for the same MD5 hash string.
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-= Bobinours =- -
loupius@BobinoursYes, you are right, we can count the number of acceptable characters differently; I used the classic case of a non-accented ASCII character set as an example.
However, I am interested in the case of 56 lowercase/uppercase letters, I have never managed to count that many... ;-) -
fiddy Contributor@BobinoursHello,
56 lowercase/uppercase letters
My alphabet only has 26 letters, which is 52 lowercase/uppercase letters ;-).
but I imagine that at least the 256 characters of extended ASCII are supported by MD5.
MD5 doesn't care about the encoding of the information. The encoding happens before it goes into MD5.
an average of 10 different words for the same MD5 hash string
Much more.
The output space size of the MD5 function is: 2^128.
The input space size is infinite.
The ratio of the two gives infinity. Yes, there is an infinite number of words that have the same hash. Except you have to find them, and since there is no link between them, that is often discouraging. This is what we call collisions. And by exploiting an interesting property of MD5: MD5(a+b) = MD5(u+b) if MD5(a)=MD5(u).
, we can do interesting things that we obviously won't talk about.
In any case, it's better to stop using MD5 and migrate to SHA512.
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fiddy ContributorYou are mixing concepts.
You should not confuse encryption functions and hashing functions.
the encryptor...is acting up...and yet this program is supposed to decrypt....
Here, we are talking about MD5, which is a hashing function. It has nothing to do with an encryption function.
The principle of a hashing function is to provide a digest from which you cannot retrieve its predecessor. The encryption function ensures the confidentiality of a message while allowing it to be decrypted if you know the key.
So to conclude, a hashing function is irreversible. And if the message is robust, you will not be able to retrieve the message from its hash. Otherwise, the hash loses its purpose.
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