how do extended validation X.509 certs work?

Question

https://www.forumatic.com/ uses an extended validation cert. wikipedia.org's entry on extended validation certs says that a cert is known to be an extended validation cert if the OID in the certificate policies extension is of the appropriate value.

How does the browser know what the appropriate value is? Here's what Google Chrome shows for the root cert in the chain:

Screenshot

The Extended Validation field looks promising. Doing "openssl x509 -in cert.pem -noout -text" gives me the following:

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 0 (0x0)
        Signature Algorithm: sha1WithRSAEncryption
        Issuer: C=US, O=The Go Daddy Group, Inc., OU=Go Daddy Class 2 Certificat
ion Authority
        Validity
            Not Before: Jun 29 17:06:20 2004 GMT
            Not After : Jun 29 17:06:20 2034 GMT
        Subject: C=US, O=The Go Daddy Group, Inc., OU=Go Daddy Class 2 Certifica
tion Authority
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
            RSA Public Key: (2048 bit)
                Modulus (2048 bit):
                    00:de:9d:d7:ea:57:18:49:a1:5b:eb:d7:5f:48:86:
                    ea:be:dd:ff:e4:ef:67:1c:f4:65:68:b3:57:71:a0:
                    5e:77:bb:ed:9b:49:e9:70:80:3d:56:18:63:08:6f:
                    da:f2:cc:d0:3f:7f:02:54:22:54:10:d8:b2:81:d4:
                    c0:75:3d:4b:7f:c7:77:c3:3e:78:ab:1a:03:b5:20:
                    6b:2f:6a:2b:b1:c5:88:7e:c4:bb:1e:b0:c1:d8:45:
                    27:6f:aa:37:58:f7:87:26:d7:d8:2d:f6:a9:17:b7:
                    1f:72:36:4e:a6:17:3f:65:98:92:db:2a:6e:5d:a2:
                    fe:88:e0:0b:de:7f:e5:8d:15:e1:eb:cb:3a:d5:e2:
                    12:a2:13:2d:d8:8e:af:5f:12:3d:a0:08:05:08:b6:
                    5c:a5:65:38:04:45:99:1e:a3:60:60:74:c5:41:a5:
                    72:62:1b:62:c5:1f:6f:5f:1a:42:be:02:51:65:a8:
                    ae:23:18:6a:fc:78:03:a9:4d:7f:80:c3:fa:ab:5a:
                    fc:a1:40:a4:ca:19:16:fe:b2:c8:ef:5e:73:0d:ee:
                    77:bd:9a:f6:79:98:bc:b1:07:67:a2:15:0d:dd:a0:
                    58:c6:44:7b:0a:3e:62:28:5f:ba:41:07:53:58:cf:
                    11:7e:38:74:c5:f8:ff:b5:69:90:8f:84:74:ea:97:
                    1b:af
                Exponent: 3 (0x3)
        X509v3 extensions:
            X509v3 Subject Key Identifier:
                D2:C4:B0:D2:91:D4:4C:11:71:B3:61:CB:3D:A1:FE:DD:A8:6A:D4:E3
            X509v3 Authority Key Identifier:
                keyid:D2:C4:B0:D2:91:D4:4C:11:71:B3:61:CB:3D:A1:FE:DD:A8:6A:D4:E
3
                DirName:/C=US/O=The Go Daddy Group, Inc./OU=Go Daddy Class 2 Cer
tification Authority
                serial:00

            X509v3 Basic Constraints:
                CA:TRUE
    Signature Algorithm: sha1WithRSAEncryption
        32:4b:f3:b2:ca:3e:91:fc:12:c6:a1:07:8c:8e:77:a0:33:06:
        14:5c:90:1e:18:f7:08:a6:3d:0a:19:f9:87:80:11:6e:69:e4:
        96:17:30:ff:34:91:63:72:38:ee:cc:1c:01:a3:1d:94:28:a4:
        31:f6:7a:c4:54:d7:f6:e5:31:58:03:a2:cc:ce:62:db:94:45:
        73:b5:bf:45:c9:24:b5:d5:82:02:ad:23:79:69:8d:b8:b6:4d:
        ce:cf:4c:ca:33:23:e8:1c:88:aa:9d:8b:41:6e:16:c9:20:e5:
        89:9e:cd:3b:da:70:f7:7e:99:26:20:14:54:25:ab:6e:73:85:
        e6:9b:21:9d:0a:6c:82:0e:a8:f8:c2:0c:fa:10:1e:6c:96:ef:
        87:0d:c4:0f:61:8b:ad:ee:83:2b:95:f8:8e:92:84:72:39:eb:
        20:ea:83:ed:83:cd:97:6e:08:bc:eb:4e:26:b6:73:2b:e4:d3:
        f6:4c:fe:26:71:e2:61:11:74:4a:ff:57:1a:87:0f:75:48:2e:
        cf:51:69:17:a0:02:12:61:95:d5:d1:40:b2:10:4c:ee:c4:ac:
        10:43:a6:a5:9e:0a:d5:95:62:9a:0d:cf:88:82:c5:32:0c:e4:
        2b:9f:45:e6:0d:9f:28:9c:b1:b9:2a:5a:57:ad:37:0f:af:1d:
        7f:db:bd:9f

I don't see anything resembling the Extended Validation field in openssl's parsing of the cert...

I believe E.V. certs are also signed by a different root key. — ewanm89, Apr 22 '12 at 22:15

Bruno · Accepted Answer · 2012-04-22T22:21:44.823

8

These values (both OID and root CA cert fingerprint) are indeed hard-coded in the browser's code. In Firefox, this is done in nsIdentityChecking.cpp.

edited Apr 22 '12 at 22:21

answered Apr 22 '12 at 22:16

Bruno

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Still they don't mean much, just the authority saying "we think we performed better verification." – ewanm89 Apr 22 '12 at 22:24
@ewanm89, part of this is done purely for commercial reasons unfortunately. Of course, by having these values hard-coded, those CAs have more power to control the market. The biggest EV certs advocates are the CAs themselves... (I've also mentioned a few related problems in [this answer](http://security.stackexchange.com/a/13614/2435)). – Bruno Apr 22 '12 at 22:32
Yeah, I just thought I should add it for the benefit of anyone reading this thread. – ewanm89 Apr 22 '12 at 22:54
@ewanm89: While part of it may be for commercial reasons, outside of the regulated public CA market, EV has no meaning anyway. To issue an EV certificate, you not only need to follow the EV verification procedure as defined by CA/B, but you also need to be audited by accredited auditing bodies which must be reviewed by browser vendors. A private root CA, cannot fulfill EV CA requirements anyway, and if you go through the lengths of submitting to browser vendors, you're effectively as trustworthy as a public CA, so an EV bar for a private root cannot really indicate anything meaningful. – Lie Ryan Feb 21 '18 at 23:07
That link leads to an error page. – user124384 Jul 31 '18 at 17:15
1

@user124384 It looks like it has moved to [`ExtendedValidation.cpp`](https://hg.mozilla.org/mozilla-central/file/0d72c7996d60/security/certverifier/ExtendedValidation.cpp) in recent versions. – Bruno Jul 31 '18 at 18:15

how do extended validation X.509 certs work?

1 Answers1

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