[Cryptography] CFB/OFB/CTR mode with HMAC for key stream

Tom Mitchell mitch at niftyegg.com
Mon May 1 17:45:00 EDT 2017

On Mon, May 1, 2017 at 2:35 PM, Tom Mitchell <mitch at niftyegg.com> wrote:
> On Mon, May 1, 2017 at 8:29 AM, Bill Frantz <frantz at pwpconsult.com> wrote:
>> On 5/1/17 at 12:07 AM, memvandal at gmail.com (Memory Vandal) wrote:
>>> I was wondering if using HMAC with something like SHA-256 to create a key
>>> stream in CFB/OFB/CTR mode is a bad idea.

Name space collisions may have made me look foolish.  :-\


There is a bit of history in the WP page.
"The definition and analysis of the HMAC construction was first
published in 1996 by Mihir Bellare, Ran Canetti, and Hugo Krawczyk,[1]
who also wrote RFC 2104. This paper also defined a variant called NMAC
that is rarely, if ever, used. FIPS PUB 198 generalizes and
standardizes the use of HMACs. HMAC-SHA1 and HMAC-MD5 are used within
the IPsec and TLS protocols."

  T o m    M i t c h e l l

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