curl --request POST \
  --url https://api.dfns.io/auth/registration/init \
  --header 'Content-Type: application/json' \
  --data '{
  "orgId": "<string>",
  "username": "<string>",
  "registrationCode": "<string>"
}'

{
  "user": {
    "id": "<string>",
    "displayName": "<string>",
    "name": "<string>"
  },
  "temporaryAuthenticationToken": "<string>",
  "challenge": "<string>",
  "rp": {
    "id": "<string>",
    "name": "<string>"
  },
  "supportedCredentialKinds": {
    "firstFactor": [
      "Fido2"
    ],
    "secondFactor": [
      "Fido2"
    ]
  },
  "authenticatorSelection": {
    "authenticatorAttachment": "platform",
    "residentKey": "required",
    "requireResidentKey": true,
    "userVerification": "required"
  },
  "attestation": "none",
  "pubKeyCredParams": [
    {
      "type": "public-key",
      "alg": 123
    }
  ],
  "excludeCredentials": [
    {
      "type": "public-key",
      "id": "<string>"
    }
  ],
  "otpUrl": "<string>"
}