Re: [Cryptography-dev] Adding support for Admissions extension

Wed, 30 Oct 2024 06:37:16 -0700

Well, to some extent certificates are suppose to be public.  But then I often deal with those that are kept out of the public's view...
It looks like this is an ITU standard from at least 2010. Unfortunately the dump is not showing the actual OID for the "Professional Information or basis for Admission:".  But I did see that it's content is suppose to be generalName. 


In many ways I kind of hate putting such information into the cert and 
that it should be external to the cert management structure. That is how 
we do it in Aviation, but Health Care always seemed to have its own set 
of drivers.



Given how this seems to be an ITU standard (would be nice to have the 
exact one(s)), and it seems to "just" be using generalName, it seems 
valid for the powers that be here to add its support.



Like I said, I don't like this approach, but it was done long ago. I 
have to send certs over very constrained wireless links and cringe on 
how policy people think they can override laws of Physics (20Kg in a 1Kg 
bag kind of stuff).



Professionally, this is good to know.  It is NOT in the Aviation 
Certificate Policy we are doing in ICAO.  But it may creep in via 
EUROCONTROL people.  I will have to dig into this at the upcoming ICAO 
meeting.



And just an aside that using RSA 2048 is not such a good idea for use 
anymore (and in Health Care?).  I am using EdDSA25519.  It has some 
resistance to attacks that ECDSA does not have, it fits over our 
wireless links, and is stronger than your 2048 keys.  But then we have 
legacy 4096 keys in Aviation and have to include support for them in our CP.




On 10/30/24 09:06, Oleg Höfling via Cryptography-dev wrote:

I hope I won't be fired for publishing the certificates out in the 
wild :-) so I'll try to black out the unrelated parts. BIO print:

```
openssl x509 -in certfile -noout -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: XXX (0xXXX)
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=DE, O=Orga, OU=OrgaUnit, CN=Authority
        Validity
            Not Before: Oct 16 10:31:30 2024 GMT
            Not After : Jul 22 10:22:29 2026 GMT

        Subject: C=DE, serialNumber=99.99999999999 + GN=spam + SN=eggs 
+ CN=bacon

        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    XXX
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Extended Key Usage:
                TLS Web Client Authentication, E-mail Protection
            X509v3 Authority Key Identifier:
                XXX
            Professional Information or basis for Admission:
                admissionAuthority:
                  DirName:C = DE, O = Authority
                Entry 1:
                  Profession Info Entry 1:
                    registrationNumber: 9-99.9.9999999999.99.999
                    Info Entries:
                      Apotheker/-in
                    Profession OIDs:
                      undefined (1.2.276.0.76.4.32)

            Authority Information Access:
                OCSP - URI:http://example.com
            X509v3 Certificate Policies:
                Policy: 1.2.276.0.76.4.145

                  CPS: 
https://www.abda.de/themen/positionen-und-initiativen/telematik/hba/

                Policy: 1.2.276.0.76.4.75
            X509v3 CRL Distribution Points:
                Full Name:

                  
URI:ldap://example.com/CN=XXX,O=XXX,C=DE?certificaterevocationlist 
<http://example.com/CN=XXX,O=XXX,C=DE?certificaterevocationlist>

            X509v3 Subject Key Identifier:
                XXX
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
email:s...@eggs.com <mailto:email%3as...@eggs.com>
            X509v3 Basic Constraints: critical
                CA:FALSE
    Signature Algorithm: sha256WithRSAEncryption
    Signature Value:
        XXX
```

The OIDs in the 1.2.276.0.76.4 range are available in public in the 
spec 
https://gemspec.gematik.de/downloads/gemSpec/gemSpec_OID/gemSpec_OID_V3.17.0.pdf


ASN.1 dump:
```
    0:d=0  hl=4 l=1614 cons: SEQUENCE
    4:d=1  hl=4 l=1334 cons:  SEQUENCE
    8:d=2  hl=2 l=   3 cons:   cont [ 0 ]
   10:d=3  hl=2 l=   1 prim:    INTEGER           :02
   13:d=2  hl=2 l=   3 prim:   INTEGER           :XXX
   18:d=2  hl=2 l=  13 cons:   SEQUENCE
   20:d=3  hl=2 l=   9 prim:    OBJECT  :sha256WithRSAEncryption
   31:d=3  hl=2 l=   0 prim:    NULL
   33:d=2  hl=3 l= 140 cons:   SEQUENCE
   36:d=3  hl=2 l=  11 cons:    SET
   38:d=4  hl=2 l=   9 cons:     SEQUENCE
   40:d=5  hl=2 l=   3 prim:      OBJECT  :countryName
   45:d=5  hl=2 l=   2 prim:      PRINTABLESTRING   :DE
   49:d=3  hl=2 l=  31 cons:    SET
   51:d=4  hl=2 l=  29 cons:     SEQUENCE
   53:d=5  hl=2 l=   3 prim:      OBJECT  :organizationName
   58:d=5  hl=2 l=  22 prim:      UTF8STRING        :Orga
   82:d=3  hl=2 l=  56 cons:    SET
   84:d=4  hl=2 l=  54 cons:     SEQUENCE
   86:d=5  hl=2 l=   3 prim:      OBJECT  :organizationalUnitName
   91:d=5  hl=2 l=  47 prim:      UTF8STRING  :OrgaUnit
  140:d=3  hl=2 l=  34 cons:    SET
  142:d=4  hl=2 l=  32 cons:     SEQUENCE
  144:d=5  hl=2 l=   3 prim:      OBJECT  :commonName
  149:d=5  hl=2 l=  25 prim:      UTF8STRING  :Authority
  176:d=2  hl=2 l=  30 cons:   SEQUENCE
  178:d=3  hl=2 l=  13 prim:    UTCTIME :241016103130Z
  193:d=3  hl=2 l=  13 prim:    UTCTIME :260722102229Z
  208:d=2  hl=3 l= 211 cons:   SEQUENCE
  211:d=3  hl=2 l=  11 cons:    SET
  213:d=4  hl=2 l=   9 cons:     SEQUENCE
  215:d=5  hl=2 l=   3 prim:      OBJECT  :countryName
  220:d=5  hl=2 l=   2 prim:      PRINTABLESTRING   :DE
  224:d=3  hl=3 l= 195 cons:    SET
  227:d=4  hl=2 l=  30 cons:     SEQUENCE
  229:d=5  hl=2 l=   3 prim:      OBJECT  :serialNumber
  234:d=5  hl=2 l=  23 prim:      PRINTABLESTRING :99.99999999999
  259:d=4  hl=2 l=  30 cons:     SEQUENCE
  261:d=5  hl=2 l=   3 prim:      OBJECT  :givenName
  266:d=5  hl=2 l=  23 prim:      UTF8STRING        :spam
  291:d=4  hl=2 l=  48 cons:     SEQUENCE
  293:d=5  hl=2 l=   3 prim:      OBJECT            :surname
  298:d=5  hl=2 l=  41 prim:      UTF8STRING        :eggs
  341:d=4  hl=2 l=  79 cons:     SEQUENCE
  343:d=5  hl=2 l=   3 prim:      OBJECT  :commonName
  348:d=5  hl=2 l=  72 prim:      UTF8STRING        :bacon
  422:d=2  hl=4 l= 290 cons:   SEQUENCE
  426:d=3  hl=2 l=  13 cons:    SEQUENCE
  428:d=4  hl=2 l=   9 prim:     OBJECT  :rsaEncryption
  439:d=4  hl=2 l=   0 prim:     NULL
  441:d=3  hl=4 l= 271 prim:    BIT STRING
  716:d=2  hl=4 l= 622 cons:   cont [ 3 ]
  720:d=3  hl=4 l= 618 cons:    SEQUENCE
  724:d=4  hl=2 l=  29 cons:     SEQUENCE

  726:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Extended 
Key Usage
  731:d=5  hl=2 l=  22 prim:      OCTET STRING      [HEX 
DUMP]:301406082B0601050507030206082B06010505070304

  755:d=4  hl=2 l=  31 cons:     SEQUENCE

  757:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Authority 
Key Identifier

  762:d=5  hl=2 l=  24 prim:      OCTET STRING      [HEX DUMP]:XXX
  788:d=4  hl=2 l= 126 cons:     SEQUENCE

  790:d=5  hl=2 l=   5 prim:      OBJECT  :Professional Information or 
basis for Admission
  797:d=5  hl=2 l= 117 prim:      OCTET STRING      [HEX 
DUMP]:3073A4333031310B300906035504061302444531223020060355040A0C1941706F7468656B65726B616D6D6572204E6F7264726865696E303C303A30383036300F0C0D41706F7468656B65722F2D696E300906072A8214004C04201318332D31302E332E323135343131313038332E31302E323234

  916:d=4  hl=2 l=  59 cons:     SEQUENCE
  918:d=5  hl=2 l=   8 prim:      OBJECT  :Authority Information Access
  928:d=5  hl=2 l=  47 prim:      OCTET STRING      [HEX DUMP]:XXX
  977:d=4  hl=2 l= 116 cons:     SEQUENCE

  979:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 
Certificate Policies
  984:d=5  hl=2 l= 109 prim:      OCTET STRING      [HEX 
DUMP]:306B305E06082A8214004C0481113052305006082B06010505070201164468747470733A2F2F7777772E616264612E64652F7468656D656E2F706F736974696F6E656E2D756E642D696E69746961746976656E2F74656C656D6174696B2F6862612F300906072A8214004C044B

 1095:d=4  hl=3 l= 137 cons:     SEQUENCE

 1098:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 CRL 
Distribution Points

 1103:d=5  hl=3 l= 129 prim:      OCTET STRING      [HEX DUMP]:XXX
 1235:d=4  hl=2 l=  29 cons:     SEQUENCE

 1237:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Subject 
Key Identifier

 1242:d=5  hl=2 l=  22 prim:      OCTET STRING      [HEX DUMP]:XXX
 1266:d=4  hl=2 l=  14 cons:     SEQUENCE
 1268:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Key Usage
 1273:d=5  hl=2 l=   1 prim:      BOOLEAN           :255
 1276:d=5  hl=2 l=   4 prim:      OCTET STRING      [HEX DUMP]:030205A0
 1282:d=4  hl=2 l=  44 cons:     SEQUENCE

 1284:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Subject 
Alternative Name

 1289:d=5  hl=2 l=  37 prim:      OCTET STRING      [HEX DUMP]:XXX
 1328:d=4  hl=2 l=  12 cons:     SEQUENCE

 1330:d=5  hl=2 l=   3 prim:      OBJECT            :X509v3 Basic 
Constraints

 1335:d=5  hl=2 l=   1 prim:      BOOLEAN           :255
 1338:d=5  hl=2 l=   2 prim:      OCTET STRING      [HEX DUMP]:3000
 1342:d=1  hl=2 l=  13 cons:  SEQUENCE
 1344:d=2  hl=2 l=   9 prim:   OBJECT  :sha256WithRSAEncryption
 1355:d=2  hl=2 l=   0 prim:   NULL
 1357:d=1  hl=4 l= 257 prim:  BIT STRING
```


Am Mi., 30. Okt. 2024 um 04:06 Uhr schrieb Robert Moskowitz 
<r...@htt-consult.com>:


    Can you do a print out of such a cert with say:

    openssl x509 -in whatever.pem -text -noout

    ?

    And perhaps an ASN.1 dump:


    openssl asn1parse -i -in whatever.pem

    I am curious as to what this extension looks like.  It is not in
    rfc5280
    and wonder if it was ever published in an rfc (which is the common
    practice when pushing a new extension for common use).

    BTW, I worked in the IETF PKIX workgroup back in the day...

    On 10/29/24 22:28, Paul Kehrer via Cryptography-dev wrote:
    > Is there a published spec that defines the ASN.1 syntax for these
    > extensions (maybe from BSI)? We generally like to have a
    specification
    > that we can use as a source of truth. For x509 I don’t have any
    > objection to adding this assuming a spec exists.
    >
    > -Paul
    >
    >> On Oct 29, 2024, at 6:54 PM, Oleg Höfling via Cryptography-dev
    >> <cryptography-dev@python.org> wrote:
    >>
    >> 
    >> Dear devs,
    >>
    >> there is an X509 extension named `Admissions`, supported e.g. by
    >> OpenSSL (https://docs.openssl.org/master/man3/ADMISSIONS/) and
    >> BouncyCastle
    >>
    
(https://people.eecs.berkeley.edu/~jonah/bc/index.html?org/bouncycastle/asn1/isismtt/x509/AdmissionSyntax.html).

    >> Would you be interested in `cryptography` supporting it as
    well? This
    >> is an extension that is used in german public healthcare and legal
    >> sectors, and I am working for one of them :-) I really enjoy
    working
    >> with `cryptography` for reading out and persisting X509
    certificates,
    >> but dealing with the `Admissions` extension requires me adding
    extra
    >> dependencies and writing extra code using other libraries I do not
    >> enjoy this much.
    >>
    >> If you agree that it could be a viable addition to the project, I
    >> would gladly contribute the necessary bits myself. I made a
    >> proof-of-concept implementation for the Admissions extension in my
    >> fork of `cryptography` to have something to discuss:
    >>
    >>
    
https://github.com/pyca/cryptography/compare/main...hoefling:cryptography:admission-extension?expand=1
    >>
    >> Example script that creates a certificate with an admission
    extension
    >> that has some dummy values:
    >> https://gist.github.com/hoefling/fa290eb33b24a2e5405cf9cdeeda03bc
    >>
    >> Of course, this is far from the state where it can be reviewed,
    >> should be split into smaller patches, is missing tests and docs
    etc etc.
    >>
    >> If you reject the idea, I would try and put the code in a separate
    >> library that depends on `cryptography` and connect them together
    >> somehow. I would be grateful for any advices on that matter -
    maybe
    >> you already had a case with a third party extension for
    >> `cryptography` being built.
    >>
    >> Last but not least - I really enjoyed hacking the working
    prototype
    >> together and fiddling with the Rust backend, kudos for having
    such a
    >> clear and concise API design!
    >>
    >> Kind regards,
    >>
    >> Oleg
    >> _______________________________________________
    >> Cryptography-dev mailing list
    >> Cryptography-dev@python.org
    >> https://mail.python.org/mailman/listinfo/cryptography-dev
    >
    > _______________________________________________
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    > Cryptography-dev@python.org
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