Connecting to World Check-One, Integration using HTTP Connected system and using the hmacsha256hash function

Question

I am able to connect to the External API with Postman using the API keys and API secrets and am successful. 
 But when I use the Integration object I get a this error.

This request requires authentication but does not specify the type of authentication expected HTTP/1.1 401 Unauthorized 
 We are trying to connect to World Check-One API and wondering if anyone else has ever connected to their API.

Soma · Answer

Make sure you are passing correct value for "Authorisation" parameter in the header. It should be in a way which the External API document suggests. 
 Authorization: Signature keyId="{API-KEY}",algorithm="hmac-sha256",
 headers="(request-target) host date content-type content-length",
 signature="{BASE64-HMAC-VALUE}"
 
Example:
Authorization: Signature keyId="4321",algorithm="hmac-sha256",
 headers="(request-target) host date content-type content-length",
 signature="Iktz/AdXHmDouNm6uBB8ZW0xcfNGuWGDxmX9TFMwuF0="