Re: [jose] Propsoed Signing Procedure

["Jim Schaad" <[e-mail]>]

You are making an assumption which is incorrect.

 

This text is in response to a request by you to outline the procedures for
not base64 encoding the content.  Thus it is completely correct that there
no difference between the JWS payload and the JWS encoded payload because
under that proposal there isn't any difference.

 

The problem with doing things piecemeal over time is that one forgets
things.  I was going to add a new section to the document as well

 

X.  Content Preparation requirements on the Application

 

Applications need to do a certain amount of preparation of the content
before it can be signed.   The only content that can be signed is a stream
of octet values.  How the stream of octet values is represented is specific
to the language and, potentially, library being used for the implementation
of JWS.  

 

Some libraries will provide helper functions that can do the preparation for
the application, however the capabilities will vary from library to library
and are not covered by this specification.

 

The compact serialization method requires that the content be placed in the
base64url character set prior to being signed.  This can be done either by
the application doing the base64url encoding on the content, or by the
application constraining the set of possible values to be signed to those in
the base64url character set.  Again this is a feature that some libraries
will provide helper functions for but how it is done will be library
specific.

 

From: Mike Jones [mailto:[e-mail]] 
Sent: Friday, June 28, 2013 9:38 PM
To: Jim Schaad; [e-mail]
Subject: RE: [jose] Propsoed Signing Procedure

 

Your description below confuses the JWS Payload (which can be any octet
sequence) and the Encoded JWS Payload (which is the base64url encoded
representation of the JWS Payload).  For instance, you made a typo in your
point 3.c.iii below by writing "JWS Payload" when you meant "Encoded JWS
Payload".

 

Likewise, your first point 3 in your proposed 8.1 should be referring to the
Encoded JWS Payload - not the JWS Payload.  Similarly, you left off the
"Encoded" in the second point 3 of your proposed 8.1.

 

Likewise, you are confusing the Encoded Payload and the Payload in your
proposed 8.2 text.  The payload has to be able to represent any octet
stream, which your text doesn't enable.  That's why we have the Encoded
Payload in the first place.

 

Do you want to revise your proposal to eliminate this confusion,
differentiating between the JWS Payload - which can represent any octet
sequence, and the JWS Encoded Payload, which is a URL-safe, JSON-string-safe
representation of that octet stream?

 

I understand that editorially you're trying to restructure the signing and
verification sections to be more agnostic to whether there are multiple
signatures.  I don't have any issue with that.

 

                                                            Thanks,

                                                            -- Mike

 

From: [e-mail] [mailto:[e-mail]] On Behalf Of Jim
Schaad
Sent: Friday, June 28, 2013 9:07 PM
To: [e-mail]; Mike Jones
Subject: [jose] Propsoed Signing Procedure

 

I would suggest something along the following lines.  It is still missing
some of the descriptive text that is required, but not a great deal of it.

 

Jim

 

 

 

5.1 Message signing or MACing

 

To create a JWS, on performs the following steps.  The order of the steps is
information, however the result of performing the steps is prescriptive.

 

1.        Verify the content to be used as the JWS Payload is an octet
stream.  If it is not then the fail.

2.        If a common signature header field exists, then serialize the
object describing the header using UTF-8 and then base64 URL that result.
This is now the Encoded JWS Header.

3.       For each signature to be created perform the following steps:

a.       Obtain the algorithm to be used for the signature operation.  This
may be in the common signature protected header, the common signature
unprotected header or the signature header objects.  If this is not a legal
and supported signature algorithm then fail.

b.      Verify that the key to be used for the signature operation is
compatible with the signature algorithm.

c.       Concatenate the following values for the octet stream to be signed:

                                                                  i.
The Encoded JWS header if it exists,

                                                                 ii.
One period character ('.')

                                                               iii.      The
JWS payload

d.      Compute the signature value using the key, the signature algorithm
and the octet stream to be signed.

e.      Base64url encode the signature value, this is the Encoded JWS
signature.

 

Section 8.1  Compact serialization

 

In order for a compact serialization to be created, the following conditions
must be met:

1.       There must be exactly one signer

2.       There must not be a common unprotected header field or a signer
header field.  These can be combined before the signature is created to form
the common protected header field.

3.       The JWS payload MUST conform to the character set which is used for
base64url encoding.  This is A-Za-z0-9 (and whatever the rest of them are)

 

The compact serialization is formed by concatenating the following items:

1.       The Encoded JWS Header,

2.       One period character ('.')

3.       The JWS Payload

4.       One period character ('.')

5.       The Encoded JWS signature

 

Section 8.2  JSON Serialization

 

The JSON serialization is an object with the following members:

Protected            - a string containing the Encoded JWS Header (OPTIONAL)

Unprotected      - an object containing any common unprotected header values
(OPTINAL)

Payload                - a string containing the JWS Payload (REQUIRED)

Signatures           - an array containing one element for each signature
created.  Each array element consists of an object with the following
members:

                Header - an object containing any signer specific
unprotected header values (OPTINAL)

                Signature - a string containing the Encoded JWS Signature
for that signer.