Troubleshooting PIV/CAC logins and Managing Certificates

Background

Using a PIV/CAC with Login.gov relies on a certificate trust chain. The identity-pki repo tracks trusted issuing certificates in source control. We need to know that a certificate is used to issue PIVs before we trust it (since not all certificates are used for issuing PIVs).

Related article: Common OpenSSL command line recipes

Steps

If a user writes in that they can’t log in to Login.gov with their PIV and get errors like “The certificate you selected is invalid”, then we are probably missing an issuing certificate for their PIV. These steps outline how to find out what that certificate is, and how to add it.

Get a user UUID, usually via uuid-lookup or salesforce-email-lookup
Download the user’s public key (we log this to S3) using oncall/download-piv-certs

Use the rails console in identity-pki to inspect the certificate that was downloaded from S3, by using the CertificateChainService.

 cert = Certificate.new(OpenSSL::X509::Certificate.new(File.read("path/to/cert")))
 chain = CertificateChainService.new.debug(cert)

It will print out a list of certificates, their issuers, and key_ids.

 ///////////////////////////////////////
 ///////////// [ CA Step: 0 ] /////////////
 ///////////////////////////////////////
 Subject: /C=US/O=U.S. Government/OU=Department of State/OU=PIV/OU=Certification Authorities/OU=U.S. Department of State PIV CA2
 Issuer: /DC=sbu/DC=state/CN=Configuration/CN=Services/CN=Public Key Services/CN=AIA/CN=U.S. Department of State AD Root CA
 -----BEGIN CERTIFICATE-----
 MIIJ5TCCB82gAwIBAgIEUbC5fzANBgkqhkiG9w0BAQsFADCBsTETMBEGCgmSJomT
 8ixkARkWA3NidTEVMBMGCgmSJomT8ixkARkWBXN0YXRlMRYwFAYDVQQDDA1Db25m
 ....
 ....
 -----END CERTIFICATE-----
 key_id: 8C:D6:D4:69:A9:E4:85:41:3A:6A:A6:5E:DA:51:1A:17:8D:92:8B:6C
 signing_key_id: CC:00:68:61:A6:A5:03:93:10:0A:1B:61:B7:87:18:C1:45:56:DA:82
 ca_issuer_dn: /DC=sbu/DC=state/CN=Configuration/CN=Services/CN=Public Key Services/CN=AIA/CN=U.S. Department of State AD Root CA
 ca_issuer_url: http://crls.pki.state.gov/AIA/CertsIssuedToDoSADRootCA.p7c
 fetching: http://crls.pki.state.gov/AIA/CertsIssuedToDoSADRootCA.p7c
 ///////////////////////////////////////

If a certificate is missing from our tracked issuing certificates, this will be nil:

 key_id = '8C:D6:D4:69:A9:E4:85:41:3A:6A:A6:5E:DA:51:1A:17:8D:92:8B:6C'
 CertificateStore.instance[key_id]
 # => nil

Load all the missing certs in the chain:

 missing = CertificateChainService.new.missing(cert)
 # => [Certificate .... ]

If you want to add the missing certificates to our repo, run rake certs:find_missing_intermediate_certs[path/to/cert.pem]

The script will prompt you to add missing certificates to the config/certs folder:
```
 Expiration: 2023-02-18 16:08:44 UTC
 Subject: /C=US/O=CertiPath/OU=Certification Authorities/CN=CertiPath Bridge CA - G3
 Issuer: /C=US/O=U.S. Government/OU=FPKI/CN=Federal Bridge CA G4
 SHA1 Fingerpint: 77d6cf512ec6054e9ddf37a37d83c4955228e21c
 Key ID: 7A:8B:3C:06:92:DC:1E:A8:D2:82:AC:1B:74:6F:74:3D:4E:D1:A8:9B

 Would you like to save this cert? Type (y)es to save.
 y
 Writing certificate to ./config/certs/C=US, O=CertiPath, OU=Certification Authorities, CN=CertiPath Bridge CA - G3.pem
```
1. Test that the certificate(s) was added correctly by closing and opening the Rails console (the certificates are loaded by config/initializers/ so it’s easier than manually running the initializer)
```
 key_id = '7A:8B:3C:06:92:DC:1E:A8:D2:82:AC:1B:74:6F:74:3D:4E:D1:A8:9B'
 CertificateStore.instance[key_id]
 => #<Certificate:0x00007fd564fa89a8 ...>
```
2. Test that the end-user certificate is now valid by running rake certs:validate_client_cert[path/to/cert.pem]
  
  The script will print whether the certificate is now valid.
```
 Certificate is valid!
```
3. Commit the new .pem file(s) to source control and make a pull request
4. Once merged, deploy the change to INT and ask the reporters to confirm the fixes