{
  "$id": "https://schema.nfh.global/CounterSignature/v2.0",
  "x-iri": "https://schema.nfh.global/CounterSignature/v2.0",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Beckn HTTP Counter-Signature",
  "description": "A signed receipt transmitted in the synchronous `Ack` response body, proving that the receiver authenticated, received, and processed the inbound request.  `CounterSignature` shares the same wire format as `Signature` but differs: - **Signer**: the response receiver (not the request sender) - **Location**: transmitted in the `Ack` response body (not in the `Authorization` header) - **`digest`**: covers the Ack response body (not the inbound request body) - **`(request-digest)`** and **`(message-id)`** MUST be included in the signing string  Signing string format: ``` (created): {unixTimestamp} (expires): {unixTimestamp} digest: BLAKE-512={base64DigestOfAckBody} (request-digest): BLAKE-512={base64DigestOfInboundRequestBody} (message-id): {messageId} ```",
  "allOf": [
    {
      "$ref": "https://schema.nfh.global/Signature/v2.0/schema.json"
    }
  ]
}