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Safely Storing User Passwords: Hashing vs. Encrypting
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TejGandhi1986
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TejGandhi1986,
User Rank: Apprentice
6/13/2014 | 9:01:50 PM
Preventing the password file from getting stolen
Thanks for the article,itis very informative and provide details on the foundations related to hashing and encryption.

Considering different chain of thoughts ,along with encryption and hashing that is used to secure passwords it is essential that the password file is well protected SAM file in windows and etc/shadow or etc/passwd file in Linux access must be restricted with multiple layers of defense to prevent it from getting stolen.

Thanks

Tej Gandhi

 
MichaelCoates
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MichaelCoates,
User Rank: Author
6/12/2014 | 4:16:00 PM
Re: Good overview
Good question. The stolen database would indeed include the salts. However, exposure of random per-user salts does not undermine their purpose and security benefits.

There are two benefits to using per-user salts

1. When using per-user salts an attacker cannot simply review the stolen password hash databse for duplicate hashes (which would indicate the same original password for both accounts). The introduction of a per-user salt ensures that even the same password will result in unique hashes.

2. An attacker cannot download a rainbow table and use it against the password hashes. A rainbow table is a large database of precomputed hashes for a variety of common passwords (or even all possible passwords of certain character sets and lengths). Without per-user salts an attacker could do a simple lookup of the stolen hash within the rainbow table to determine the original password. The introduction of per-user salts means the rainbow table is useless.


Sure, an attacker could incorporate the salt into a brute force attack. But the purpose of a salt isn't to stop brute force. It's to accomplish the two items mentioned above (duplicate hashes and rainbow tables). As I mentioned in the article, the iterative hashing approach that exists in bcrypt/scrypt/PBKDF2 is the defense against brute force attacks on the password hash.

 

Hope that helps.

Michael

 
chiefwilson
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chiefwilson,
User Rank: Apprentice
6/11/2014 | 9:57:04 PM
Re: Good overview
Michael,

Thank you for a well-written article. I agree that hashing passwords with added salt provides far greater security than simply encrypting passwords. My question is simple: If a malicious actor steals a database of password hashes, won't this database include the salts as well, thereby nullifying the purpose of the salt, which is to defend against brute force dictionary and rainbow table attacks?
Marilyn Cohodas
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Marilyn Cohodas,
User Rank: Strategist
6/4/2014 | 2:51:46 PM
Re: Good overview
Thanks, Michael. One of the things I've been hearing about more and more is that personal information has become much more valuable a target for cybercrime than, for example credit cards. If that's the case, then your message about hashing versus encryption is one that InfoSec pros should definitely take to heart. 
MichaelCoates
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MichaelCoates,
User Rank: Author
6/4/2014 | 1:02:50 PM
Re: Good overview
The largest misconception is that since encryption is good for protecting information in some situations it is therefore appropriate for all situations involving sensitive data. As discussed above, encryption is really the wrong choice for protecting passwords.

Second, that any hashing algorithm is sufficient for password hashing. Selecting a weak algorithm like md5 or failing to user per user salts places passwords at extreme risk if the hash file is stolen.

-Michael
Marilyn Cohodas
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Marilyn Cohodas,
User Rank: Strategist
6/4/2014 | 12:34:09 PM
Good overview
Thanks for your detailed overview, Michael. You say that to propertly secure user invormation today, application developers must starts with "a proper understanding of fundamental security controls and the protection of user passwords using modern hashing algorithms." What do you think is the biggest misunderstanding of security that app developers have?


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