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Fb1h2s aka Rahul Sasi's Blog

Cracking Salted Hashes

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Garage 4 Hackers
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Cracking Salted Hashes
Web Application Security: - The Do’s and Don’ts of “Salt Cryptography”
Data Base security has become more critical as Databases have become more open. And Encryption
which is one among the five basic factors of data base security.
It’s an insecure practice to keep your sensitive data like Password, Credit Card no etc unencrypted in
you database. And this paper will cover the various Cryptography options available and do and don’ts of
Even if you have encrypted your data that doesn’t mean that your data’s are fully secured, and this
paper will be covered in an Attacker perspective.
Slat Cryptography.
Assume a user’s hashed password is stolen and he is known to use one of 200,000 English words as his
password. The system uses a 32-bit salt. The salted key is now the original password appended to this
random 32-bit salt. Because of this salt, the attacker’s pre-calculated hashes are of no value (Rainbow
table fails). He must calculate the hash of each word with each of 232 (4,294,967,296) possible salts
appended until a match is found. The total number of possible inputs can be obtained by multiplying the
number of words in the dictionary with the number of possible salts:
2^{32} \times 200 000 = 8.58993459 \times 10^{14}
To complete a brute-force attack, the attacker must now compute almost 900 trillion hashes, instead of
only 200,000. Even though the password itself is known to be simple, the secret salt makes breaking
the password increasingly difficult.
Well and salt is supposed to be secret, to be simple if the attacker knows what salt is used then we
would be back again to step one. So below listed are few possible ways you could use to crack salted

Orginal Source attached...
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  1. amutu's Avatar
    why crypt() should not be used? It's not clear to me......i understood about constant salts, but not about php's crypt function().
  2. fb1h2s's Avatar
    Hi amutu, it's not that it shouldn't be used, its just that its not that safe using it. Consider I got the hashes saved using crypt output , a 13 char hash. Now the first two chars are the hashes "2" (char hash). Its fairly easy with current computing power to crack a 2 char salted password .


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