Authentication to the API is performed via HTTP Basic Access Authentication. Provide your API key as the basic auth username value. You do not need to provide a password. If you need to authenticate via bearer auth (e.g., for a cross-origin request) see Token Authentication
If you don’t use a client which can handle the HTTP Basic Access Authentication request for you, make sure you send the request as a header with the following format:
Authorization: Basic cHJpdmF0ZV9CUW9raWtKT3ZCaUkySGxXZ0g0b2xmUTI6
base64encode('username:password') = base64 value to pass in the header
base64encode('private_BQokikJOvBiI2HlWgH4olfQ2:') = cHJpdmF0ZV9CUW9raWtKT3ZCaUkySGxXZ0g0b2xmUTI6
In the above example the username and empty password are base64 encoded. Note the : sign after your private key in the above example.
curl "https://api.hips.com/v2/echo_with_private_key" \
-u "private_BQokikJOvBiI2HlWgH4olfQ2:"
curl "https://api.hips.com/v2/echo_with_private_key" \
-H "Authorization: Basic cHJpdmF0ZV9CUW9raWtKT3Z
curl uses the -u flag to pass basic auth credentials (adding a colon after your API key prevents cURL from asking for a password).
You must replace private_BQokikJOvBiI2HlWgH4olfQ2 with your private API key.