Some attributes are going to come in as raw binary objects, such as userCertificate. In the case of certificates we want to base64-encode them. Other binary attributes we'll deal with as they arise.

What API call triggers this, and how is is snet via the RPC?

Below is the response from a curl call to cert_request, which should be find for the web.

{
"error": null,
"id": 0,
"result": {
"result": {
"certificate": "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",
"issuer": "CN=IPA Test Certificate Authority",
"md5_fingerprint": "fa:74:80:3c:62:67:33:97:75:ab:be:0d:97:c6:90:bb",
"serial_number": "1006",
"sha1_fingerprint": "b5:ee:74:e6:53:95:37:b2:c8:4d:c1:a2:17:c7:06:04:46:a6:10:57",
"subject": "CN=ipa.ayoung.boston.devel.redhat.com,O=IPA",
"valid_not_after": "Tue Sep 08 09:12:35 2015 UTC",
"valid_not_before": "Wed Sep 08 09:12:35 2010 UTC"
}
}
}

Was never a problem with the XMLRPC api, just in the mod_wsgi based UI