ietf-openpgp
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Wordsmithing in 3.6.3.3

1998-04-02 12:23:49
I'm probably unusually thick, but I found the wording of 3.6.3.3
difficult.  Despite words to the contrary, it took me a while to
get away from the idea that it was being run through multiple
hashes -- I've been looking at too many HMACs lately -- rather
than simply being duplicate data sent into the same hash.  The
current second paragraph is:
-------------------------------------------------------------------
Initially, one or more hash contexts are set up as with the other S2K
algorithms, depending on how many octets of key data are needed.  Then
the salt, followed by the passphrase data is repeatedly hashed until
the number of octets specified by the octet count has been hashed.  The
one exception is that if the octet count is less than the size of the
salt plus passphrase, the full salt plus passphrase will be hashed even
though that is greater than the octet count.  After the hashing is done
the data is unloaded from the hash context(s) as with the other S2K
algorithms.
-------------------------------------------------------------------
Would it be too redundant to add a little more to it, like this?
-------------------------------------------------------------------
Initially, one or more hash contexts are set up as with the other S2K
algorithms, depending on how many octets of key data are needed.  Then
the
salt, followed by the passphrase data is repeatedly hashed until the
number of octets specified by the octet count has been hashed.  That is,
each hash context is fed the initial zero-valued octets (if any), the
salt, the passphrase, the salt again, the passphrase again, and so on
until the specified octet count has been hashed, not counting the
initializing zero-valued octets.  The one exception is that if the octet
count is less than the size of the salt plus passphrase, the full salt
plus passphrase will be hashed even though that is greater than the
octet
count.
 
After the hashing is done the data is unloaded from the hash context(s)
as with the other S2K algorithms.
----------------------------------------------------------------------


-- 
        Jim Gillogly
        Trewesday, 11 Astron S.R. 1998, 19:21
        12.19.5.1.1, 7 Imix 19 Cumku, Third Lord of Night

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