A hash algorithm is a function which takes a variable size input and produces a fixed size output. The algorithm tries to make it difficult to predict the output for a given input, find two inputs with the same output, or reconstruct the input from the output.

learn more… | top users | synonyms (1)

80
votes
6answers
26k 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
4k 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 ...
29
votes
2answers
9k 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 ...
18
votes
1answer
2k views

Collision rate for different hash algorithms

Is there any collision rate measure for popular hashing algorithms (md5, crc32, sha-*)? If that depends only from output size, it's quite trivial to measure, but I suppose that depends also of ...
18
votes
3answers
3k 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
2answers
176 views

Complexity of web certificate attacks

I heard a while ago about someone exploiting md5 weaknesses to create a web certificate with the same md5 that a different certificate has. They were able to create a certificate through bad issuing ...
2
votes
3answers
227 views

Identify client based on computed hash

I'm currently developing a web application which will serve data to iPhone clients. In order to be the owner of the data, I don't want other clients to be able to get it. I thought I could use a ...
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 ...
27
votes
3answers
3k 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. ...
3
votes
1answer
834 views

How to apply FIPS to Microsoft Access database with custom VBA

As the software engineer on a project, I have been asked to make a Microsoft Access application, with custom interfaces running custom VBA. That part is going just fine. Recently though I was asked to ...
13
votes
2answers
26k views

What are the differences between MD5, SHA and RSA?

MD5 tools output hexadecimal values. In the same manner, do SHA and RSA together produce a hexadecimal (or any other) output? What are the differences between the MD5, SHA and RSA algorithms?
3
votes
2answers
322 views

MD5 display format

When I run MD5 algorithm I am getting an output in numeric and a few lower case letters. Obviously it uses all numeric digits and rarely i saw some lower case alphabet letter. I need to understand ...
5
votes
2answers
2k 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
520 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 ...
12
votes
6answers
7k 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 ...
14
votes
3answers
9k views

Whats the difference between MAC vs hash

What is the difference between the two algorithms? One difference that I know of, is that MAC is keyed and hash is not.
13
votes
7answers
7k views

What are the realistic, and most secure crypto for Symmetric, Asymmetric, Hash, Message Authentication Code ciphers?

I'm interested in updating this two pronged question for 2011: What cryptology is most appropriate for low-powered devices (such as a cellphone), and yet still effective? What cryptology is most ...
28
votes
11answers
1k views

Does hashing a file from an unsigned website give a false sense of security?

Consider this. Many websites with software downloads also make available MD5 or SHA1 hashes, for users to verify the integrity of the downloaded files. However, few of these sites actually use HTTPS ...
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?
15
votes
5answers
2k views

The aescrypt 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 aescrypt reference implementation. Looking at the source, it seems that the encryption key is derived from the IV and the ...
65
votes
2answers
13k views

What are rainbow tables and how are they used?

Where can I find one? Is there a pot of gold at the end? How do I protect against them? From the Area51 proposal This question was IT Security Question of the Week. Read the Sep 09, 2011 blog ...
292
votes
11answers
52k views

How to securely hash passwords?

If I hash passwords before storing them in my database, is that sufficient to prevent them being recovered by anyone? I should point out that this relates only to retrieval directly from the ...
280
votes
4answers
83k views

Do any security experts recommend bcrypt for password storage?

On the surface bcrypt, an 11 year old security algorithm designed for hashing passwords by Niels Provos and David Mazieres, which is based on the initialization function used in the NIST approved ...
13
votes
6answers
1k views

Does prepending a salt to the password instead of inserting it in the middle decrease security?

I read somewhere that adding a salt at the beginning of a password before hashing it is a bad idea. Instead, the article claimed it is much more secure to insert it somewhere in the middle of the ...