Re: why HMAC (Keyed-Hashing for Message Authentication)?
From: Panu Hämäläinen (panu.hamalainen_at_NOSPAM.tut.fi.invalid)
Date: 12/23/03
- Next message: Andrew McCall: "Security through wide system use?"
- Previous message: Adam Russell: "Re: Why is Win Explorer accessing the Net?"
- In reply to: Bernhard Kuemel: "why HMAC (Keyed-Hashing for Message Authentication)?"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Date: Tue, 23 Dec 2003 11:56:35 +0200
> What is the advantage of HMAC over simply passing
> hash(strcat(key,message)) along with the message?
If you use a standard iterative hash function (e.g. SHA), the construction
allows length extension attacks, i.e., using the hash value for
authenticating a longer message with the same key. If you put the key in the
end, attacking is little more complicated (key recovery attack) but still
possible. HMAC is designed so that it resists both. (see "Practical
Cryptography," Niels Ferguson, Bruce Schneier)
-- Panu
- Next message: Andrew McCall: "Security through wide system use?"
- Previous message: Adam Russell: "Re: Why is Win Explorer accessing the Net?"
- In reply to: Bernhard Kuemel: "why HMAC (Keyed-Hashing for Message Authentication)?"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Relevant Pages
|
|
