Specific to the security of passwords: hashing, entropy, cracking, resets, lockouts, etc.

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91
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4answers
21k views

Recommended # of iterations when using PKBDF2-SHA256?

I'm curious if anyone has any advice or points of reference when it comes to determining how many iterations is 'good enough' when using PBKDF2 (specifically with SHA-256). Certainly, 'good enough' is ...
17
votes
6answers
1k views

Appropriate password requirements for a login (OpenID) service/provider/delegate/thing

This is with regards* to Stack Exchange's upcoming OpenID provider (and in particular, discussion about password requirements). Currently, password requirements are: Must contain 3 of: lower case ...
14
votes
6answers
629 views

Primary Key as Salt?

Is it okay to use the primary key as the salt in a Users table? The only disadvantage that I can see is if the PK changes (unlikely), then the passwords break. What are your thoughts?
7
votes
3answers
2k views

How does LastPass' grid multi-factor authentication work behind the scenes?

I understand how to use the Grid multi-factor authentication as a user but how does it work technically? Specifically how can just a few letters from the grid be enough to decrypt any secret defined ...
11
votes
3answers
3k views

Additional security of keyfile on top of a master password for KeePass

I use KeePass + Dropbox to manage and synchronize my passwords across my devices. This system works really great and I trust KeePass' security model. However my biggest remaining concern is the ...
14
votes
4answers
1k views

How are browser saved passwords vulnerable?

Most browsers offer to save the password after entering it on many logon pages. What types of vulnerabilities are there for such saved passwords. I'm interested in what ways malware on web pages ...
66
votes
7answers
56k views

Certificate based authentication vs Username and Password authentication

What are the advantages and drawbacks of the certificate based authentication over username and password authentication? I know some, but I would appreciate a structured and detailed answer. UPDATE ...
8
votes
3answers
2k views

time to crack file-encryption password - more than just iteration

I have often seen that takes x amount of time to crack a certain length password. But this just seems to be the amount of time it takes to iterate through all the possibilities. What about the time it ...
25
votes
3answers
5k views

Password manager vs remembering passwords

I have always thought that you are not supposed to use a password manager but to keep your passwords in your head, but lately I have thought about the pros and cons of having a password manager. Some ...
4
votes
2answers
2k views

Cisco IOS question - password management, service password encryption types

I'm university student studying for my certification exam, and I was doing some reviewing today when I found a question that I can't find an answer to. Basically, in the CCNA3 2.4.1 Cisco Netacademy ...
9
votes
2answers
952 views

Stretching a hash, many iterations versus longer input string

I have been reading up on various password hashing schemes, for example the SHA-based Crypt proposed by Ulrich Drepper and used in some Linux versions. A recurring theme here is to 'strengthen' or ...
9
votes
4answers
729 views

Should I obfuscate passwords before hashing? Should I pre-hash them on the client? What about salts?

For fun, and in my spare time I'm creating a simple CMS for my own purposes (with hopes to release for wider use... later), using PHP. I'm currently working on the login scheme now, and have a few ...
96
votes
6answers
37k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
5
votes
4answers
5k views

Brute force vs other methods of recovering passwords from shadow file

Do you know any good approach for de-hashing/actually bruteforcing hashed passwords in the shadow file? On various operating systems, any good solutions/methods/programs. Or is it better to upload ...
23
votes
4answers
3k views

Recommended policy on password complexity

Is there any research on how how a password complexity policy can increase or decrease the quality of passwords? If you don't have any requirements on the password then probably 90% of users will use ...
32
votes
2answers
12k views

HMAC - Why not HMAC for password storage?

Nota bene: I'm aware that the good answer to secure password storage is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. Let's say ...
5
votes
2answers
1k views

Password History/Password policy

I'm referring to "remembered" password that the domain keeps so a user cannot reuse that password until it has expired in what was set at Password Policy on DC (W2003/W2008). Where is password ...
18
votes
3answers
4k views

MySQL OLD_PASSWORD cryptanalysis?

The password hash used for MySQL passwords prior to version 4.1 (now called OLD_PASSWORD()) seems like a very simple ad-hoc hash, without salts or iteration counts. See e.g an implementation in ...
5
votes
3answers
409 views

How can I detect users that have requested AD Administrators to reuse an expired password?

There is a trend among companies I've worked at where administrators (or helpdesk folks) give a user a courtesy extension of the old expired password... rather than forcing the user to change it. ...
14
votes
4answers
2k views

Looking for example of well-known app using unsalted hashes

Does anyone know of a well-known application that still uses unsalted hashes for password storage? I'm looking for an example for an upcoming lecture on Rainbow Tables, and I think it would add ...
29
votes
3answers
4k views

Is there any advantage to splitting a password?

I've been reading about the LANMAN (LM) hash and I'm curious about a particular part of the algorithm. The LM hash is computed as follows: The user’s ASCII password is converted to uppercase. ...
60
votes
12answers
11k views

How reliable is a password strength checker?

I've tested the tool from Microsoft available here which tests password strength and rates them. For a password such as "i am going to have lunch tonight", the tool rates it's strength as "BEST" and ...
11
votes
5answers
2k views

Is Skype secure enough to transmit passwords?

Is it considered "secure" to send a password in a skype message and delete the message after the recipient remembered the password?
11
votes
3answers
4k views

How can I prevent someone from accessing a Windows XP system via boot disk?

Apparently a computer system protected by a a login password, e.g. Windows XP, can be easily hacked by someone with physical access to it using methods like this one: ...
25
votes
4answers
2k views

Why do some sites block pasting into username or password input fields?

I use a few websites that prevent me from copying & pasting into the username or password fields. It's quite frustrating when using a password manager, and if anything I'd think it discourages ...
11
votes
9answers
2k views

Why do we authenticate by prompting a user to enter both username and password? Does prompting the password only suffice?

I don't know why do we authenticate by prompting the user to enter both username and password. In my mental model, prompting password only suffices. The reason is as follows: Assume there are x ...
9
votes
3answers
2k views

How can I mitigate the threat that DPAPick poses to my DPAPI protected data?

The Windows Data Protection API (DPAPI) is the suggested method for storing secrets on Windows systems (such as database passwords required by ASP.Net applications). DPAPick was presented at BlackHat ...
24
votes
5answers
4k views

Security impact of using a public password for free WiFi

We have a WiFi network that we want to be public and free. Does having a password that is known to everyone provide any additional security advantage to the people using this network as opposed to ...
5
votes
2answers
3k views

Reference implementation of C# password hashing and verification

Does anyone have a reference implementation (ideally 3rd party certified, or government approved) way one-way hash a password for C# and or Java? Ideally,I'd like to see something that includes a ...
3
votes
2answers
552 views

BlackBerry client authenticating to Java Web Service

I already asked this question at StackOverflow here: http://stackoverflow.com/questions/4970681/blackberry-app-security and was directed to this site, can anyone pitch in as to how I can solve this ...
11
votes
8answers
3k views

What chars should I not allow in passwords?

I am planning to develop a website that require that the users register a username and a password. When I let the user choose a password, what chars should I allow the users to have in the password? ...
12
votes
6answers
8k views

Is PBKDF2-based System.Cryptology.RFC2898DeriveBytes() “better” for Unicode Password hashing than traditional methods?

When is it appropriate to use RFC2898DeriveBytes versus a typical hash? Update I now understand that a KDF is typically used to create a symmetric key for possible use in encrypting a stream. I ...
9
votes
6answers
420 views

How can I ensure that default passwords are no longer in use?

There are two situations in which 'default' passwords get used on a network: A new user is registered. In her registration pack, along with her new username, e-mail address and so on is her initial ...
3
votes
1answer
1k views

Does the Ophcrack LiveCD require hash collection via programs like pwdump?

When I used the Ophcrack LiveCD recently, the program automatically ran without me manually loading any hashes. Question is: If Ophcrack does not automatically find hashes, how can I go about ...
8
votes
6answers
8k views

One Time Passwords. Using OTP at Windows, Ubuntu and internet sites

my question is this: Is there a way (software,hardware/token or web-ware) to use One Time Passwords in the following scenarios: Logon to my pc/laptop (windows or ubuntu) Logon to sites with OTP ...
20
votes
5answers
1k views

Why do some websites and programs restrict password characteristics?

There are some websites and even programs that I use that have rediculous password restrictions. Lots of forums for instance restrict passwords to ~32 characters. Others enforce a restricted charset. ...
81
votes
9answers
145k views

Where can I find good dictionaries for dictionary attacks?

I’m wondering where I can find good collections of dictionaries which can be used for dictionary attacks? I've found some through Google, but I’m interested in hearing about where you get your ...
6
votes
2answers
956 views

Storing third-party auth info securely

Suppose there's a multi-user web application that requires access to user's mailbox (on third-party service, like gmail, etc.). This access needs to be persistent. Which means we'd have to store user ...
4
votes
6answers
944 views

What are the weaknesses of this password-generation-method? How can it be improved?

I recently came up with the problem, that I have much more accounts, than I'm able to remember passwords. I don't want to use a password-safe, because I cannot access it on another computer, I lose ...
35
votes
10answers
3k views

Is there a method of generating site-specific passwords which can be executed in my own head?

I was thinking recently about password security. My goal is to have mostly random passwords, that are different for each site. But you also should be able to remember them (or re-generate them) ...
8
votes
5answers
214 views

Citations for inadvisability of globally unique password

I am looking for an authoritative source to back up my position in a disagreement over password policy. I am having a disagreement with a client about the user identification/authentication process ...
12
votes
4answers
1k views

MS-SQL Password Storage

What would be your recommendation for replacement of an MD5 hash approach to password storage within an MS-SQL database be?
39
votes
5answers
8k views

Are GUIDs safe for one-time tokens?

I see a lot of sites use GUIDs for password resets, unsubscribe requests and other forms of unique identification. Presumably they are appealing because they are easy to generate, unique, ...
16
votes
2answers
3k views

How secure is Keychain on OS X?

Keychain is a built-in app on OS X that stores all of the user credentials, and allows for one to keep encrypted notes in an easily accessible way. Does anyone know how secure Keychain is? I know ...
24
votes
10answers
5k views

Password Management within an Organisation

Within an organisation there are many passwords such as those for root accounts on servers, hosting accounts, router logins and other such things, that need to be kept track of. I know in some ...
45
votes
38answers
9k views

What is your way to create good passwords that can actually be remembered?

What are the methodologies which can be used to generate "human" good quality password? They have to ensure a good strength and also easy to remember for a human being.
6
votes
8answers
3k views

Retrieving OSx Keychain passwords

I have a computer forensics style osx login.keychain file that I am trying to find the passwords from. I have a very weak mac which I used crowbarkc on to try and brute force but the horsepower is ...
4
votes
0answers
1k views

Hints for safe passwords that are easy to remember [duplicate]

Possible Duplicate: What is your way to create good passwords that can actually be remembered? What are good hints to create passwords that are both safe and comfortable? By comfortable I ...
16
votes
5answers
3k views

The AES Crypt implementation hashes a password 8192 times to generate the key. Is this necessary?

I'm considering encrypting some small files (hundreds of kb apiece) using the AES Crypt reference implementation. Looking at the source, it seems that the encryption key is derived from the IV and the ...
73
votes
13answers
21k views

Why do sites implement locking after three failed password attempts?

I know the reasoning behind not letting infinite password attempts - brute force attempts is not a meatspace weakness, but a problem with computer security - but where did they get the number three ...