curl --request POST \
  --url https://perp-api.phoenix.trade/v1/auth/login/service/challenge \
  --header 'Content-Type: application/json' \
  --data '
{
  "client_id": "string"
}
'

{
  "expires_at": "<string>",
  "key_id": "<string>",
  "message": "<string>",
  "nonce": "<string>"
}