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HMAC is a method for constructing a message authentication code based on a cryptographic hash function.
0
votes
Key derivation using the main AES encryption key and some plain text?
It would be better to use your main key to derive two separate keys, one for encryption, and one for HMAC... and using the info parameter to distinguish the two keys. …
3
votes
SHA3 HMAC key padding
In lieu of any answers; I've compared my own implementation with the few test vectors I've been able to find (one of which can be found here) and it would appear that yes, keys longer than the block-s …
4
votes
Encryption and HMAC key derivation
If you go with Scrypt (which I would recommend you do), there are no restrictions on the size of the passphrase... and Scrypt consumes it internally with one round of PBKDF2-HMAC-SHA256 anyway. … When generating the HMAC authentication and encryption keys, would I benefit at all from using SHA-512?
No, you wouldn't. In fact, this step is unnecessary. …
10
votes
Accepted
How to use HMAC-SHA1, HMAC-SHA2 in conjunction with AES
Using a HMAC provides this integrity. … A HMAC solves this problem as it uses a key - meaning that an attacker is unable to create a valid HMAC unless they have a valid key (which only you possess). …
5
votes
Using one-way hash functions as the encryption method
"Frequency analysis of the output might help determine simple words in
the ciphertext such as 'the' etc if that word is repeated and sent
multiple times. This isn't necessarily a problem as it' …
1
vote
RSA digital signature vs authenticated cipher
Your options should really be either using GCM mode, or using a non-authenticated mode (such as CBC) and calculating the HMAC (with something like HMAC-SHA256) post-encryption. … The second option, encrypt-then-hmac, is fine too, but there's more room for error. …
29
votes
What is the difference between a HMAC and a hash of data?
With a HMAC, a key is used when calculating the hash value, so unless the attacker has the key, they're unable to calculate a valid hash value of the modified data. …