a method for constructing a message authentication code based on a cryptographic hash function.

learn more… | top users | synonyms

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. ...
12
votes
1answer
2k views

Why can't I use the same key for encryption and MAC?

I wrote a simple file encryption program as an example of how to do encryption correctly, but after reading a questions about encryption + MAC, I think I made a mistake by using the same key for both. ...
12
votes
2answers
1k views

Timing attack against HMAC in authenticated encryption?

In an answer to another question of mine, it was noted that a class using standard string comparison functions when checking the HMAC in authenticated encryption would make the class vulnerable to ...
-5
votes
2answers
132 views

Protection of online image file (ancient manuscript) [duplicate]

I am going to protect an image file (ancient manuscript) which will be available online for everyone to download. I want to protect the file in these situations: When it's on the server, I need to ...
52
votes
5answers
35k views

How and when do I use HMAC?

I was reading HMAC on wikipedia and I was confused about a few points. Where do I use HMAC? Why is the key part of the hash? Even if someone successfully used a "length-extension attack", how would ...
9
votes
2answers
6k views

Salted hashes vs HMAC?

Most of discussions involving access credentials include references to "hashing salted passwords". Is this another way to referring to the HMAC algorithm or a totally different operation? Different or ...
6
votes
4answers
4k views

HMAC/PBKDF2 vs Simple hashing algorithm for web service authentication?

We are in the process of creating a web service and have been investigating ways of securing it. In reality, the service is likely to get very little traffic and the data is likely to be of little use ...
6
votes
1answer
532 views

Should password hashes be encrypted or HMACed?

Assume I am hashing user passwords with PBKDF2, bcrypt, scrypt, or some other secure key derivation function. Are there: tangible security benefits, precedents, and respected research for ...
3
votes
1answer
258 views

When to use HMAC alongside AES?

One of my clients wants to provide an URL to each of his customers to register in a system. This URL would contain a query string parameter with some data (e.g. code, email and name) from his clients ...