GET PKIMessage endpoint returning illegal base64 data at input byte

[KarthikaRajendran11]

I am trying to implement OTA on a ios device. The device sends /GetCACert and /GetCACaps request successfully. In the third step, when the device send operation=PKIOperation\u0026message=MIAGCSq... request, the server returns illegal base64 data at input byte This error is returned specifically at this line :

scep/server/transport.go

Line 111 in 2c96089

return base64.StdEncoding.DecodeString(msg2)

I am running the scepserver as a standalone project. I realize this might not be an issue with the server but wanted to confirm once. Would anyone happen to know what the issue might be ?

[jessepeterson]

Hmm, we definitely have used OTA with SCEP in MicroMDM. But because the GetCACaps tells it that it uses a POST you shouldn't see the message= part on the PKIOperation. Is this a GET or POST request?

[KarthikaRajendran11]

Thanks for the response. It was a GET request. I was able to get a response when I replaced

scep/server/transport.go

Line 106 in 2c96089

if op == "PKIOperation" {

with

if op == "PKIOperation" {
	execPath, err := exec.LookPath("base64")
	if err != nil {
		fmt.Println(err.Error())
		return nil, err
	}
	cmd := exec.Command(execPath, "--decode", "/Users/karthikarajendran/Desktop/iphone.txt")
	d, err := cmd.Output()
	if err != nil {
		fmt.Println(err.Error())
		return nil, err
	}
	msg = string(d)
}

And this how the endpoint was called from Postman
http://localhost:8080/scep?operation=PKIOperation&message=MIAGCSqGSIb... iPhone logs showed the same call.