I agree with Mike here. Though PKCE only needs the ASCII(STRING) one. On Fri, Jan 30, 2015 at 12:38 PM, Mike Jones <michael.jo...@microsoft.com> wrote:
> > http://tools.ietf.org/html/draft-ietf-jose-json-web-signature-41#section-1.1 > uses this notation: > > > > UTF8(STRING) denotes the octets of the UTF-8 [RFC3629 > <http://tools.ietf.org/html/rfc3629>] representation > > of STRING, where STRING is a sequence of zero or more Unicode > > [UNICODE > <http://tools.ietf.org/html/draft-ietf-jose-json-web-signature-41#ref-UNICODE>] > characters. > > > > ASCII(STRING) denotes the octets of the ASCII [RFC20 > <http://tools.ietf.org/html/rfc20>] representation > > of STRING, where STRING is a sequence of zero or more ASCII > > characters. > > > > This is unambiguous and has already been vetted by the IESG and SecDir, so > I would use exactly this wording. > > > > OCTETS(STRING) is ambiguous, since for the same string there are many > possible representations as octets, including ASCII, UTF-8, UTF-16, UTF-32, > and EBCDIC. > > > > -- Mike > > > > *From:* OAuth [mailto:oauth-boun...@ietf.org] *On Behalf Of *John Bradley > *Sent:* Friday, January 30, 2015 11:33 AM > *To:* Brian Campbell > *Cc:* oauth; Naveen Agarwal > *Subject:* Re: [OAUTH-WG] PKCE: SHA256(WAT?) > > > > Have a look at the latest version I added OCTETS(STRING) to show the > conversion. ASCII(STRING) seemed more confusing by drawing character > encoding back in. > > > > I was tempted to call it a octet array without the terminating NULL of > STRING but didn’t want to introduce array. > > > > Let me know what you think. > > > > On Jan 30, 2015, at 1:56 PM, Brian Campbell <bcampb...@pingidentity.com> > wrote: > > > > But, while it may be clear to you, what I'm saying here is that it's not > clear to a reader/implementer. > > Somehow the conversion from a character string to an octet string needs to > be clearly and unambiguously stated. It doesn't have to be the text I > suggested but it's not sufficient as it is now. > > Something like this might work, if you don't want to touch the parts in > 4.2 and 4.6: "SHA256(STRING) denotes a SHA2 256bit hash [RFC6234] of the > octets of the ASCII [RFC0020] representation of STRING." > > An "octet sequence using the url and filename safe Alphabet [...], with > length less than 128 characters." is ambiguous. Octets and characters are > intermixed with no mention of encoding. But they're not interchangeable. > > > > > > On Fri, Jan 30, 2015 at 7:15 AM, Nat Sakimura <sakim...@gmail.com> wrote: > > I do not think we need ASCII(). It is quite clear without it, I suppose. > > > > In 4.1, I would rather do like: > > > > code_verifier = high entropy cryptographic random > 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. > > > > Nat > > > > 2015-01-30 22:51 GMT+09:00 Brian Campbell <bcampb...@pingidentity.com>: > > 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 > > > > > > > > > > > > > > > > -- > > Nat Sakimura (=nat) > > Chairman, OpenID Foundation > http://nat.sakimura.org/ > @_nat_en > > > > >
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