0
votes
1answer
58 views

Should I use HMAC in this situation

I need to store a big message encrypted on a server. What I am about to do is: Encrypt the message with a AES key; (Authentication) Hash the message with SHA512 and encrypt the hash with RSA priv ...
0
votes
0answers
44 views

Payment Application Integration - Encryption or HMAC

Doing an integration with an online payment provider. Payment provider will be making a web request to my server to provide some information about the basket content. On my end there's no payment ...
1
vote
1answer
69 views

Should HMAC key be changed regularly? Should it be kept secret at all times?

I am doing an HMAC of some cipher-text, IV and encryption algorithm. Right now I am using a hard-coded key that is known to both sender and receiver. I was wondering if the key should be changed once ...
3
votes
3answers
134 views

How to simply and efficiently generate different keys from one password?

I saw here that using the same key to encrypt and mac (in that order) a message could eventually be unsafe. What is the best way to generate two different keys from the same password (using a PBKDF ...
1
vote
1answer
1k views

How is the HMAC key exchanged?

Just wondering about this. Does it need a PKI to work?
9
votes
1answer
967 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. ...
4
votes
3answers
253 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.
3
votes
3answers
302 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 ...
4
votes
1answer
169 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 ...
11
votes
1answer
978 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? ...
5
votes
1answer
407 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 ...