X-HubSpot-Signature validation fails when request has certain Unicode characters

[arickp1]

This is for a workflow extension that I've written. The workflow extension takes form submission values via contact tokens in the workflow settings, and passes them to a webhook I've made, which relays those form submission values to another system.

I'm noticing in my application logs that my value of the X-HubSpot-Signature isn't matching the one in the request headers when the request contains a certain Unicode character. It's some "line separator character" (I'm guessing this is from customers copy/pasting from Microsoft Word into a HubSpot form)

Other Unicode characters work; I tested the signature validation when the body contained Korean text, and that worked fine.

Here's a sample request body that would cause me compute a mismatching signature:

{"callbackId":"ap-7084102-215042484774-1-0","origin":{"portalId":7084102,"actionDefinitionId":1970,"actionDefinitionVersion":5,"extensionDefinitionId":1970,"extensionDefinitionVersionId":5},"context":{"source":"WORKFLOWS","workflowId":36738539},"object":{"objectId":58401,"objectType":"CONTACT"},"fields":{"ticket_type":"task","subject":"Unicode body","due_date":"12","comment":"Hello\u2028\nThank you,","priority":"low","type":"30","tags_space_delimited":"test hubspot zendesk","status":"open"},"inputFields":{"ticket_type":"task","subject":"Unicode body","due_date":"12","comment":"Hello\u2028\nThank you,","priority":"low","type":"30","tags_space_delimited":"test hubspot zendesk","status":"open"}}

The character appears right before "Thank you". If I do another request that doesn't contain this \u2028 character then my signature checks out.

[dennisedson]

@PJagdale! 👋  Long time no chat!

Have you run into this before