Sign Challenge (Web Socket API)

The subscribe and unsubscribe requests to web socket private feeds require a signed challenge
message with the user api_secret.

The challenge is obtained as is shown in Section Web Socket API Public (using the api_key).

Authenticated requests must include both the original challenge message (original_challenge) and the signed (signed_challenge) in JSON format.

Challenge

The challenge is a UUID string.

The steps to sign the challenge are the same as the steps to generate an authenticated REST request
except for step 1 which now is just the challenge string:

1. Hash the challenge with the SHA-256 algorithm
2. Base64-decode your api_secret
3. Use the result of step 2 to hash the result of step 1 with the HMAC-SHA-512 algorithm
4. Base64-encode the result of step 3

The result of the step 4 is the signed challenge which will be included in the subscribe request.

The table below shows the expected output from example inputs: