S/MIME: Extracting certificate with multiple email values fails

[urz-hgw]

Version

Tested with version 6.2.40

Installation method

Installed in Debian Buster using default Debian repo

Expected behavior

The signed mail should be accepted by Sympa and delivered to the list members.

Actual behavior

The mail is rejected by sympa with the following error message:

sympa,3,sympa_msg[853]: err main::#243 >
Sympa::Spindle::spin#83 > Sympa::Spindle::ProcessIncoming::_twist#204 >
Sympa::Message::check_smime_signature#1323 Sympa::Message
<destination@listen.example.com.1623673874.9819>: 
Could not extract certificate for mailaddress@example.com

Additional information

The used mailing list only accepts signed mails. The certificate in use has multiple email values due to the fact that each user in our organization has at least one primary and one alternative email address. One of the email values does match the sender address so the verification is correct. When I remove all email aliases from the certificate except the one I use as sender for the mailing list, the mail is correctly delivered to the members.

Best regards
Daniel

[ikedas]

@urz-hgw , could you please show us any example of the certificate "with multiple email values"?

(Sensitive information, e.g. subject and issuer of the certificate, actual emails in any attributes etc., should be masked.)

[urz-hgw]

Hi @ikedas

Sure, here is the output of
openssl x509 -in cert.pem -text

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C = DE, O = Verein zur Foerderung eines Deutschen Forschungsnetzes e. V., OU = DFN-PKI, CN = DFN-Verein Global Issuing CA
        Validity
            Not Before: Jun 16 11:44:10 2021 GMT
            Not After : Jun 15 11:44:10 2024 GMT
        Subject: C = DE, ST = STATE, L = CITY, O = ORGNAME, SN = SN, GN = Daniel, CN = Daniel SN
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                RSA Public-Key: (4096 bit)
                Modulus:
                    ca:0e:db:18:1b:95:3d:37:79:fd:f4:0a:71:b4:37:
                    df:a8:f3:0d:a1:80:2f:0d:a9:2d:c3:f4:73:b5:62:
                    ...
                    ...
                    ...
                    3b:2d:42:f0:6f:80:fc:8b:bf:e1:09:5d:47:80:3d:
                    34:70:eb:06:98:5f:fa:36:8a:6c:b0:02:54:1a:3d:
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Certificate Policies: 
                Policy: 1.3.6.1.4.1.22177.300.1.1.4
                Policy: 1.3.6.1.4.1.22177.300.1.1.4.8
                Policy: 1.3.6.1.4.1.22177.300.2.1.4.8

            X509v3 Basic Constraints: 
                CA:FALSE
            X509v3 Key Usage: critical
                Digital Signature, Non Repudiation, Key Encipherment
            X509v3 Extended Key Usage: 
                TLS Web Client Authentication, E-mail Protection
            X509v3 Subject Key Identifier: 
                BE:0D:A9:40:08:BE:0D:A9:BE:0D:A9:BE:0D:A9:79:57:BE:0D:A9:F2
            X509v3 Authority Key Identifier: 
                keyid:BE:0D:A9:A1:F9:F2:BE:0D:A9:E0:AD:BE:0D:A9:09:1F:E8:BE:0D:A9:

            X509v3 Subject Alternative Name: 
                email:alias1@example.com, email:alias2@example.com
            X509v3 CRL Distribution Points: 

                Full Name:
                  URI:http://cdp1.pca.dfn.de/dfn-ca-global-g2/pub/crl/cacrl.crl

                Full Name:
                  URI:http://cdp2.pca.dfn.de/dfn-ca-global-g2/pub/crl/cacrl.crl

            Authority Information Access: 
                OCSP - URI:http://ocsp.pca.dfn.de/OCSP-Server/OCSP
                CA Issuers - URI:http://cdp1.pca.dfn.de/dfn-ca-global-g2/pub/cacert/cacert.crt
                CA Issuers - URI:http://cdp2.pca.dfn.de/dfn-ca-global-g2/pub/cacert/cacert.crt

    Signature Algorithm: sha256WithRSAEncryption
         3b:b5:29:77:1b:8b:d5:c1:4e:6b:1d:4d:d2:5d:e7:e2:5f:f6:
         53:94:85:6e:c4:b5:89:0e:b0:dc:84:ef:c6:91:5b:9e:a5:f9:
         ...
         ...
         34:be:ad:69:98:42:a6:0a:61:12:0a:7c:2f:81:c1:da:9b:53:
         3b:b5:29:77:1b:8b:d5:c1:4e:6b
-----BEGIN CERTIFICATE-----
#####
#####
#####
-----END CERTIFICATE-----

The important section is at X509v3 Subject Alternative Name.

Best regards
Daniel

[ikedas]

@urz-hgw , could you please apply this patch and check if the problem will be solved (and certificate with single email will also be processed properly)?

[urz-hgw]

Hi @ikedas

thanks for the immediate patch. I tested it and the problem seems to be solved.
Mails are sent correctly using certificates with single and multiple email values.

[ikedas]

@urz-hgw , thank yor for confirming! This fix will be included in the next stable release, 6.2.64.