Several of your co-workers are having a discussion over the etc/passwd file. They are at odds over what types of encryption are used to secure Linux passwords. (Choose all that apply.)
A.
Linux passwords can be encrypted with MD5
B.
Linux passwords can be encrypted with SHA
C.
Linux passwords can be encrypted with DES
D.
Linux passwords can be encrypted with Blowfish
E.
Linux passwords are encrypted with asymmetric algrothims
Explanation:
:
MD5 is hashing function (128bit, RFC1321, R.Rivest 1991).
DES and Blowfish are symmetric crypto algorithms.
Answer: C and D, but not A
By default in Red Hat it is MD5, in Ubuntu SHA512, In suse blowfish.
You can change the bydefault encryption method also in your system by customized it in file “/etc/login.defs”
# If set to MD5 , MD5-based algorithm will be used for encrypting password
# If set to SHA256, SHA256-based algorithm will be used for encrypting password
# If set to SHA512, SHA512-based algorithm will be used for encrypting password
# If set to DES, DES-based algorithm will be used for encrypting password (default)
I have no doubt that linux distribution use MD5 or SHA for hashing. The problem, or maybe trick, could be with terminology used in the question.
If someone uses encryption, then there should be a way to decrypt (or restore) the original message from encryption form.
Hash functions are not reversible. They are just one way function so you’ll never get an original message from any hash value (but you can from ciphertext!). In my opinion this is not question about encryption, this is matter just about hashing.
Honestly, I’m not sure what would be the right answer here, but I wouldn’t mix hashing and encryption.
BTW. Passed exam with 95,2% in less than one hour. 🙂
I agree with COSMO, hashing is not encryption.
I have yet to do the exam. I am worried that the exam uses many of these questions listed here on the actual exam.
I’ve been going through all the example questions and picking out the anwsers I believe to be right then writing notes on what i have gotten wrong.
In this case I picked A, B, C, D due to the fact that they must be meaning what hash algorithm is used and not which encryption algorithm.
I was surprised not to see SHA listed so I googled it and sure enough SHA-512 is used in linux. Now maybe SHA != SHA-512. Arch linux uses SHA-512 by default and there are many ways to implement SHA-512 due to MD5 being vulnerable to collisions attacks.
Man I hope the test isn’t too tough haha. Its expensive and I don’t want to write it a second time.
I choose ACD
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