anybody know it?
Please show

Its one way encryption - there is noway to decrypt the passwd file. The only way you can really discover a password is to carry out a dictionary attack where you have a program encrypt every word in a 'dictionary' and then compare the encrypted word to each encrypted entry in the password file.

Buy why do you want to know about cracking a password file??

Jamie...

i only want to know how it been encrypted

Have a read up on the unix crypt() function, that'll describe in depth how the encription works. Newer systems use a different algorithm I believe.

HTH

Jamie...

You may have already seen this, but I wanted to piont it out since it was a great explanation. http://www.linuxquestions.org/questi...&threadid=4427

Ok this is how it's been encrypted.
"DES 56bit"

DES is a block cipher--meaning it operates on plaintext blocks of a given size (64-bits) and returns ciphertext blocks of the same size. Thus DES results in a permutation among the 2^64 (read this as: "2 to the 64th power") possible arrangements of 64 bits, each of which may be either 0 or 1. Each block of 64 bits is divided into two blocks of 32 bits each, a left half block L and a right half R

DES works on bits, or binary numbers--the 0s and 1s common to digital computers. Each group of four bits makes up a hexadecimal, or base 16, number. Binary "0001" is equal to the hexadecimal number "1", binary "1000" is equal to the hexadecimal number "8", "1001" is equal to the hexadecimal number "9", "1010" is equal to the hexadecimal number "A", and "1111" is equal to the hexadecimal number "F".

DES works by encrypting groups of 64 message bits, which is the same as 16 hexadecimal numbers. To do the encryption, DES uses "keys" where are also apparently 16 hexadecimal numbers long, or apparently 64 bits long. However, every 8th key bit is ignored in the DES algorithm, so that the effective key size is 56 bits. But, in any case, 64 bits (16 hexadecimal digits) is the round number upon which DES is organized.

/Raz

actually, it is possible to decrypt... as long as you have a few supercomputers handy and a few years to waste

Actually no it's not possible to decrypt it.

When you decrypt something you follow a mathematical formula using some values "which is normally the secret key" which then gives you the plan text.

In this case it's a block cipher encryption with a secret key been the original text your trying to match.

So you're simply character matching the end encryption string to get the source plain text string.

That was my pedantic answer for the day.

ok... i won't argue the point last time i disagreed with a moderator i was proved dramatically wrong.

Newer systems may also support MD5 (Mine does :-), with the advantage of having a passwd that is longer than 8 chars and an even harder algorithm. This is done (I believe) by installing mcrypt, and editing /etc/login.defs

Yes depending on what version of Linux you use.
Redhat 6.2 and above uses the MD5 hash algorithm.

RFC1321
"The algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input.

It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest.

The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA.