$id: https://schema.beckn.io/CounterSignature/v2.0
$schema: https://json-schema.org/draft/2020-12/schema
title: CounterSignature
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}
  ```
x-tags: [common]
$ref: https://schema.beckn.io/Signature/v2.0