An open discussion list for topics related to the eduGAIN interfederation service.

[Alex Stuart <Alex.Stuart AT jisc.ac.uk>]

Hi Nicole, I'm giving a UK federation update at the REFEDS meeting so will 
mention this. I'm around until the TNC closing plenary on Thursday & happy to 
chat informally during the week.

Alex

> On 3 Jun 2022, at 16:11, Nicole Roy <nroy AT internet2.edu> wrote:
> 
> Thanks Alex, this is really good/important information. I’m wondering if 
> this might be a good thing to discuss at, say, the upcoming REFEDS meeting?
> 
> Nicole R
> 
>> On Jun 3, 2022, at 8:47 AM, Alex Stuart <Alex.Stuart AT jisc.ac.uk> wrote:
>> 
>> Dear Colleagues,
>> 
>> We in the UK federation team are reviewing the cryptographic strength of 
>> our metadata publication service. Integrity & authenticity of our 
>> aggregates (including our eduGAIN upstream feed) is provided by a 2K RSA 
>> key, SHA-256 signature and digest algorithms. We are using a 4K RSA key in 
>> our MDQ service, and considered the questions: should we be migrating to 
>> the 4K key, and by when? TL;DR Yes, by 2030.
>> 
>> I hope our analysis is interesting for the member federations of eduGAIN.
>> 
>> We have taken the eduGAIN upstream feeds from the eduGAIN API [0] and 
>> determined the cryptographic parameters of each. The data below presents 
>> the triples (RSA key size, signature algorithm, digest algorithm) and the 
>> number of eduGAIN upstream feeds which use that triple.
>> 
>> (2048, 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256', 
>> 'http://www.w3.org/2001/04/xmlenc#sha256'): 34
>> (3072, 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256', 
>> 'http://www.w3.org/2001/04/xmlenc#sha256'): 4
>> (4096, 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256', 
>> 'http://www.w3.org/2001/04/xmlenc#sha256'): 32
>> (4096, 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha512', 
>> 'http://www.w3.org/2001/04/xmlenc#sha512'): 1
>> 
>> Given this data, I've collated security strengths as per tables 2 and 3 of 
>> NIST SP 800-57 part 1 rev 5 [1] and the footnotes to table 1 in the 
>> implementation guide for FIPS 140-2 [2] to determine:
>> 
>> - For the first triple, the key size of 2048 is the limiting factor. 
>> Strength 112.
>> - For the second triple, all three quantities have estimated strength 128.
>> - For the third triple, increasing the key size to 4K (strength 150 
>> according to the formula in [2]) does not increase the strength above 128 
>> because the algorithms limit strength to 128
>> - For the last triple, the algorithms have strength > 256 and it's key 
>> size that's the limiting factor again. Strength 150.
>> 
>> The UK federation feed is one of the 34 federations in the top line of the 
>> data. Is that a bad thing? Not necessarily. We still conform to the 
>> eduGAIN profile [3]. And NIST estimate that this is acceptable through 
>> 2030 (Table 4 of [1]).
>> 
>> We have a migration route to higher strength that is available by 
>> transitioning to the 4K MDQ key. We intend to do this in the next couple 
>> of years as we re-engineer our metadata publication toolchain.
>> 
>> We note that the Romanian federation uses SHA-512 algorithms in its 
>> eduGAIN upstream and with its federation members (which include Shibboleth 
>> and simpleSAMLphp entities) so there is a route to higher strength for our 
>> eduGAIN upstream and domestically once we have transitioned to the 4K key.
>> 
>> Any comments, advice or gotchas gratefully received.
>> 
>> Regards,
>> Alex
>> 
>> [0] Documentation of eduGAIN database access API
>> https://technical.edugain.org/api
>> 
>> [1] Recommendation for key management
>> https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57pt1r5.pdf
>> 
>> [2] Implementation Guidance for FIPS 140-2 and the Cryptographic Module 
>> Validation Program
>> https://csrc.nist.gov/csrc/media/projects/cryptographic-module-validation-program/documents/fips140-2/fips1402ig.pdf
>> 
>> [3] eduGAIN SAML profile
>> https://technical.edugain.org/doc/eduGAIN-saml-profile.pdf
>> 
>> —
>> Alex Stuart (he/him)
>> Technical Development Manager (Trust and Identity)
>> alex.stuart AT jisc.ac.uk
>> 
>> 
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>> 
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> 

—
Alex Stuart (he/him)
Technical Development Manager (Trust and Identity)
alex.stuart AT jisc.ac.uk