a method for constructing a message authentication code based on a cryptographic hash function.
35
votes
4answers
11k 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.
...
8
votes
1answer
259 views
When authenticating ciphertexts, what should be HMACed?
Some have argued for using AES-256-CTR with HMAC-SHA-256 for authenticated encryption over AEAD-specific modes like EAX and GCM.
However, when doing, this, what should be HMAC'd? And how? ...
6
votes
2answers
400 views
HMAC Based Request Signing - Storing the Salt
I'm working on a (non high security) project that currently isn't live but might go live at some point.
We have a REST API (implemented using Restlet and Neo4j) running on a server and an Android ...
5
votes
4answers
1k 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 ...
5
votes
1answer
116 views
Why a symmetric key for HMAC?
I am working on securing a RESTful API and am using the Amazon AWS HMAC model as my guide. I am struggling with coming up with a secure way to store the symmetric keys on my end. What is the standard ...
5
votes
1answer
68 views
Authentication by Signing or MAC?
I'm still new to security, so I'm sorry if this question doesn't make sense or if I'm completely off base with something. I've got some messages I want to encrypt (probably with AES-256-CBC) and send ...
4
votes
2answers
94 views
HMACSHA512 versus Rfc2898DeriveBytes for password hash
We are currently using HMACSHA512 in .net, with a 128Char (64byte) validation key
The salt is 64 char randomly generated string.
We allocated 2048 length on the database for the hashed base64 string ...
4
votes
3answers
99 views
What SSL options should not be used?
What SSL options should be avoided, due to recently discovered weaknesses? This might include symmetric algorithms, or MAC functions.
4
votes
1answer
169 views
Random number for HTTPS Message Authentication Code (MAC)
Recently I found that Netscape used quite simple algorithm to generate random number for Message Authentication Code to establish an HTTPS connection (Netscape used time, process identification ...
4
votes
1answer
201 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 ...
4
votes
2answers
118 views
Online banking proof of transaction for vertification in court
So, when i do an online payment transaction i "sign" my transaction with my digipass using some sort of a MAC (HMAC) with a shared key and some information that is unique for this transaction.
But ...
4
votes
1answer
48 views
How do I build a secure signing mechanism on top of HMAC
Say we have a system with strong shared keys (not passphrases), and we're trying to sign messages sent by the server that will be visible to an attacker. E.g. storing session state in a signed cookie.
...
4
votes
1answer
129 views
Is there a tree hash form of MAC that can be used when encrypting data for storage on S3 using multipart upload?
I am storing files on S3, some of which are very large, and need to be stored encrypted. I had planned on using Galois Counter Mode since it includes the MAC, however this won't work with multipart ...
3
votes
3answers
1k views
Is a HMAC-ed password is more secure than a bcrypt-ed or scrypt-ed password?
Given an option , which one should I choose , a HMAC for storing a password securely or a bcrypt or scrypt library?
3
votes
2answers
154 views
Reusing HMAC state for multiple messages
I have a secret key k and message m. I send m || HMAC(m, k) to some other party, who can verify the integrity of m, assuming that they know k.
Suppose I have multiple messages m1, m2, and so on. ...
3
votes
3answers
1k views
How/When do i use HMAC?
I was reading HMAC on wikipedia and i was confused at 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 ...
3
votes
1answer
71 views
Does the HMAC of symmetric key revealed weakens the encryption?
If I reveal the HMAC of encryption key, does it weaken the secrurity of the payload ?
e.g, I would construct following security packet
cipher: bf_cbc
IV: initialization vector to the cipher
key-md5: ...
2
votes
2answers
351 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 ...
2
votes
1answer
119 views
Can a salted hash be an effective MAC?
An HMAC is basically a "keyed hash". Only the correct message and the correct key will produce a particular hash digest efficiently.
Conceptually speaking, the same can be said for a salted hash; ...
2
votes
1answer
81 views
HOTP with as HMAC hashing algoritme a hash from the SHA-2 family
I'm looking into using a OTP solution.
HOTP is a OTP solution that is based on a HMAC with as hashing algorithm SHA-1. The standards defines it this way.
But... SHA1 (as we know) has been a ...
2
votes
3answers
346 views
Proper hash_hmac key creation
I'm looking for, but unable to find, some definitive information on how long to make the secret and what characters are useable in creating a HMAC signature in PHP using SHA256.
I found some ...
2
votes
1answer
122 views
Web service HMAC authentication/anti-replay
I am creating a web service, which handles various requests from web clients. The client and server share a big secret key S, and when one part wants to send data, it calculates the token as follows:
...
2
votes
3answers
176 views
HMAC What is secure manner to distribute shared secret between client and server?
I am looking at ways to secure http communication using HMAC. My understanding is that in this scenario the client and the server both know a secret. This means the secret must be first generated on ...
2
votes
3answers
79 views
How do I transfer the HMAC?
I have a file I'd like to encrypt with a symmetric key using AES-256 and then use an HMAC for integrity. So I don't "roll my own" scheme which I know is a big mistake, what are the standards for using ...
1
vote
2answers
57 views
How to guarantee counter synchronisation between client and server for counter in hmac-based one time password implementation?
This is a clone of a question I posted on Stack Exchange. Thought I might catch the eye of some different people who could help here.
We are trying to implement a hmac-based one time password ...
1
vote
3answers
141 views
Validate hmac with hashed stored key
What if an HMAC is correctly generated and sent with the data to the server, so far I know the server needs to know the original data with which the MAC was created in order to re-create the MAC and ...
