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| --- This message came from the IEEE 802.11 Working Group Reflector ---
> I am confused in reading 11-14/1104r1 on these CIDs because it does not seem consistent in the naming. > Is it supposed to be SHA1 or SHA-1 for example (as you note). I think it is supposed to be "SHA-1". Please note the following part of 14/1104r1, where I've added emphasis: Regarding terminology, it seems
the hashes themselves are SHA-1, SHA-256 and SHA-384. However, the HMACs which use the latter two should be (and generally are) HMAC-SHAn[-len] to avoid confusion with the truncated HMACs.
It seems OK, though, to keep HMAC-SHA-1 since it seems harder to think the 1 might be a truncation length, and this aligns with the referenced RFC 2202 at 2619.48. > So to help those of us that do not work with the security protocols daily, what is the appropriate names...can we safely say that it is supposed to be SHA1, SHA256, SHA128.
I don't think so. There is a reference to FIPS PUB 180-3-2008 in the standard. This is available at http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf and explicitly states near the beginning that "This Standard specifies five secure hash algorithms - SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512". > Given the nominal names then I understand from your suggestion that the "-xxx" is then the amount to truncate to. (without the word truncate to prefix the name). Mark -- Mark RISON, Standards Architect, WLAN English/Esperanto/Français Samsung Cambridge Solution Centre Tel: +44 1223 434600 Innovation Park, Cambridge CB4 0DS Fax: +44 1223 434601 ROYAUME UNI WWW: http://www.samsung.com/uk From: *** IEEE stds-802-11 List *** [mailto:STDS-802-11@xxxxxxxx]
On Behalf Of Jon Rosdahl --- This message came from the IEEE 802.11 Working Group Reflector ---
Hi Dan, As doc 11-14/1104r1 has a lot of CIDs, it took a bit of reading to find where your concern area was in the document. (for those reading along it is I believe CID 3432, 3426, 3427, 3429). I am confused in reading 11-14/1104r1 on these CIDs because it does not seem consistent in the naming. Is it supposed to be SHA1 or SHA-1 for example (as you note). So to help those of us that do not work with the security protocols daily, what is the appropriate names...can we safely say that it is supposed to be SHA1, SHA256, SHA128.
Given the nominal names then I understand from your suggestion that the "-xxx" is then the amount to truncate to. (without the word truncate to prefix the name). The other parts that are noted as needing to be change you do not comment on. Do we need to say "delete securely" in all cases or is "delete" sufficient. does "destroy" imply "delete securely" and thus it is a valid term to use, and should be used when ever we mean "delete securely" Thanks,
----------------------------------------------------------------------------- On Thu, Sep 18, 2014 at 1:14 AM, Dan Harkins <dharkins@xxxxxxxxxxxxxxxxx> wrote: --- This message came from the IEEE 802.11 Working Group Reflector ---
Hello, I may not be at the 11mc session where 11-14/1104r1 is presented so I want to get discussion on it started on the mailing list. There are some issues with the proposed description of various designations of the Secure Hash Algorithm family of hash functions. In an effort to obtain what the author views as "consistency" he has introduced ambiguity and, in my opinion, incorrectness. There are 3 families of the Secure Hash Algorithm. There's the 1st family of SHA, (which is just designated SHA1) and there's the 2nd family of SHA (known as SHA2) which is SHA256 and SHA512, including truncated versions of each, SHA224 is a truncated version of SHA256 and SHA384 is a truncated version of SHA512. The 3rd family of SHA, SHA3 is a weird beast that we don't need to trouble ourselves with since we're not using it. It is important to understand, though, that SHA1, SHA256, and SHA512 are different. They are not just truncated versions of the same function. And while SHA256 does actually produce 256-bits of digest output, SHA1 does not produce 1-bit of digest output, it produces 160-bits. But we (802.11) do truncate the output of SHA family hash functions. For instance, we sometimes want only the first 128-bits of SHA1. Just to make things more complicated, we also use the HMAC construct with a SHA family algorithm. So how to deal with identifying the appropriate algorithm in the appropriate family of SHA, whether it is alone or as HMAC, and how to identify the particular output bit length that we are concerned with? 11-14/1104r1 does a poor job. Let me propose a better way: * the particular algorithm of the family is used without any hyphens— for example, it's SHA256 not SHA-256, and it's SHA1 always. * when we want to truncate we add a hyphen and indicate the bit length we want to use— for example, it's SHA256-128 (not sure why we'd do this but it's an example) or SHA1-128. * if we don't add a hyphen and number indicating truncation then the entire length of the algorithm output is used. * if we want to use the HMAC construct we prepend "HMAC-" to the SHA family algorithm indicated, including any possible indication of truncation— for example, HMAC-SHA256 or HMAC-SHA1-128. * if we don't prepend "HMAC-" then we are using the algorithm directly, and not as a keyed hash function. While 11-14/1104r1 does this correct in some cases— it proposes to change "HMAC-SHA-256" to "HMAC-SHA256"-- it does it wrong in other cases— it proposes to change "SHA1" to "SHA-1". Also, if we adopt this more correct way of referring to these various incarnations of hashing we do not need to say something like "Truncate-128(HMAC-SHA1(xxx))" we just say HMAC-SHA1-128(xxx)". Minor grammatical gripe: there is no such algorithm called "HMAC-SHA1-64", or even "HMAC-SHA-1-64" so we should not be using the definite article when describing the use of SHA1 in an HMAC construct while truncating the output to 64 bits. Please modify 11-14/1104r1 to adopt this more correct terminology before it gets adopted. regards, Dan. _______________________________________________________________________________
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