That's definitely an improvement (to me anyway). Checking that the rest of the document uses those notations appropriately, I think, yields a few other changes. And probably begs for the "ASCII(STRING) denotes the octets of the ASCII representation of STRING" notation/function, or something like it, to be put back in. Those changes might look like the following:
In 4.1.: OLD: code_verifier = high entropy cryptographic random ASCII [RFC0020] octet sequence using the url and filename safe Alphabet [A-Z] / [a-z] / [0-9] / "-" / "_" from Sec 5 of RFC 4648 [RFC4648], with length less than 128 characters. NEW (maybe): code_verifier = high entropy cryptographically strong random STRING using the url and filename safe Alphabet [A-Z] / [a-z] / [0-9] / "-" / "_" from Sec 5 of RFC 4648 [RFC4648], with length less than 128 characters. In 4.2.: OLD: S256 "code_challenge" = BASE64URL(SHA256("code_verifier")) NEW (maybe): S256 "code_challenge" = BASE64URL(SHA256(ASCII("code_verifier"))) In 4.6.: OLD: SHA256("code_verifier" ) == BASE64URL-DECODE("code_challenge"). NEW (maybe): SHA256(ASCII("code_verifier")) == BASE64URL-DECODE("code_challenge"). On Thu, Jan 29, 2015 at 8:37 PM, Nat Sakimura (=nat) <n...@sakimura.org> wrote: > I take your point, Brian. > > In our most recent manuscript, STRING is defined inside ASCII(STRING) as > > STRING is a sequence of zero or more ASCII characters > > but it is kind of circular, and we do not seem to use ASCII(). > > What about re-writing the section like below? > > STRING denotes a sequence of zero or more ASCII [RFC0020] > <http://xml2rfc.ietf.org/cgi-bin/xml2rfc.cgi#RFC0020> characters. > > OCTETS denotes a sequence of zero or more octets. > > BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per Section 3 > <http://xml2rfc.ietf.org/cgi-bin/xml2rfc.cgi#Terminology> producing a > ASCII[RFC0020] <http://xml2rfc.ietf.org/cgi-bin/xml2rfc.cgi#RFC0020> > STRING. > > BASE64URL-DECODE(STRING) denotes the base64url decoding of STRING, per Section > 3 <http://xml2rfc.ietf.org/cgi-bin/xml2rfc.cgi#Terminology>, producing a > sequence of octets. > > SHA256(OCTETS) denotes a SHA2 256bit hash [RFC6234] > <http://xml2rfc.ietf.org/cgi-bin/xml2rfc.cgi#RFC6234> of OCTETS. > > > > > > > On Jan 30, 2015, at 08:15, Brian Campbell <bcampb...@pingidentity.com> > wrote: > > In §2 [1] we've got "SHA256(STRING) denotes a SHA2 256bit hash [RFC6234] > of STRING." > > But, in the little cow town where I come from anyway, you hash bits/octets > not character strings (BTW, "STRING" isn't defined anywhere but it's kind > of implied that it's a string of characters). > > Should it say something more like "SHA256(STRING) denotes a SHA2 256bit > hash [RFC6234] of the octets of the ASCII [RFC0020] representation of > STRING."? > > I know it's kind of pedantic but I find it kind of confusing because the > code_verifier uses the url and filename safe alphabet, which has me second > guessing if SHA256(STRING) actually means a hash of the octet produced by > base64url decoding the string. > > Maybe it's just me but, when reading the text, I find the transform > process to be much more confusing than I think it needs to be. Removing and > clarifying some things will help. I hate to suggest this but maybe an > example showing the computation steps on both ends would be helpful? > > Also "UTF8(STRING)" and "ASCII(STRING)" notations are defined in §2 but > not used anywhere. > > And §2 also says, "BASE64URL-DECODE(STRING) denotes the base64url decoding > of STRING, per Section 3, producing a UTF-8 sequence of octets." But what > is a UTF-8 sequence of octets? Isn't it just a sequence octets? The > [RFC3629] reference, I think, could be removed. > > [1] https://tools.ietf.org/html/draft-ietf-oauth-spop-06#section-2 > > > Nat Sakimura > n...@sakimura.org > > > > > >
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