[Ndn-interest] Interest Signature

[Zhiyi Zhang]

On Mon, Jan 14, 2019 at 10:01 AM Mosko, Marc <mmosko at parc.com> <
mmosko at parc.com> wrote:

> (Due to a change at PARC, my current email address was not a subscriber to
> this list, so I had to cancel and re-post this message).
>
> Out of curiosity, I looked through the Gerrit on the new signed interest.
> I do like this direction better than the old signed interest where it is
> all munged in the name.
>
> I noticed at the end of the code review comments there is the statement
> "The signature should not cover Name-TYPE and Name-Length."  I did not see
> it in the comments, but I assume you are applying the same logic to the
> Parameters and SignatureInfo fields?
>

Actually not. The reason why we don't include Name's T and L is because
after generating the signature value, we need to append a
SignedInterestSha256Digest component to the end of the current name, thus
changing the Name's L.
This cuase extra overhead when verifying the signature -- receiver needs to
calculate and modify the L before signature verification.


>
> I think that is not correct.  When computing a digest over multiple
> fields, you need to delimit those fields somehow (a special character or
> length encoding, etc.).  Otherwise, you could have a first field with the
> values of the later fields and the later fields empty and get the same
> digest and thus the same signature.  For example, if my digest is over
> fields A and B, if I do not delimit them, I could have A="abc" and B="def"
> or A="abcdef" and B="" and they would look the same.
>
> I think this sentence is confusing.  Maybe use more commas or break it up
> or use set notation.
>
> >>> The cryptographic signature that is included in the
> ``InterestSignatureValue`` element covers all bytes of the ``Name`` element
> excluding the ``ParametersSha256Digest`` component, the Parameters element
> if presents, and the SignatureInfo.
>
> It could be read that the signature _excludes_ the Parameters and
> SignatureInfo.  You also use "bytes" and then "component" which mixes
> measurements.
>

Thank you for your comments. I will fix this.


>
> So it appears that the signature is only on the tuple (Name \
> ParametersSha256Digest, Parameters, SignatureInfo).  Usually one would
> makes those contiguous memory to simplify the digest calculation, so I
> would have expected the BNF to have Parameters and SignatureInfo directly
> after Name, assuming that the BNF implies normal ordering.
>

That's right. I will propose this to the reviewers. (Actually I did the
same things in NDN-Lite's signed Interest implementation.)


> Marc
>
> ________________________________________
> From: Ndn-interest <ndn-interest-bounces at lists.cs.ucla.edu> on behalf of
> Zhiyi Zhang <Zhiyi.Zhang at ucla.edu>
> Sent: Saturday, January 12, 2019 11:35:33 AM
> To: 侯 ?博
> Cc: mini-ndn at lists.cs.ucla.edu; ndn-interest at lists.cs.ucla.edu
> Subject: Re: [Ndn-interest] Interest Signature
>
> Actually, we have a pending commit waiting to be merged into NDN-TLV
> specification: https://gerrit.named-data.net/c/NDN-TLV/+/4942
> This commit defines the new NDN Signed Interest format.
> Also, there is a corresponding implementation in ndn-lite library:
> https://github.com/named-data-iot/ndn-lite/blob/master/encode/signed-interest.h
> and
> https://github.com/named-data-iot/ndn-lite/blob/master/encode/signed-interest.c
> .
>
> Hope it helps.
>
> Best,
> Zhiyi
>
> On Fri, Jan 11, 2019 at 8:20 PM 侯 ?博 via Ndn-interest <
> ndn-interest at lists.cs.ucla.edu<mailto:ndn-interest at lists.cs.ucla.edu>>
> wrote:
> Hello all,
> I want to add signature for Interest packet. So I do some actions as
> follow:
> Firstly, I add a member named m_signature in Interest.hpp.
> Secondly, I add set and get function for this field of m_signature in
> interest.hpp.
> Thirdly, I change the function of wireEncode and wireDecode in
> interest.cpp to encode and decode it.
> Finally, I  add a value for m_signature  in ndn-consumer.cpp.
> However, when I run the test program of ndn-simple,it shows the folloing
> errors，is there anyone can help me to resolve it.
>
> terminate called after throwing an instance of
> 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<ndn::Interest::Error>
> >'
> what():  unrecognized element of critical type 4294967295
>
> Thanks a lot.
>
>
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