A signer can use this operation to sign a signature request by registering a signature he procuded on his own.
The signature is automatically anchored on behalf of the owner of the signature request.
The signature anchor created is added to the list of signature anchors of the signature request.
This is a publicly accessible endpoint: authentication is not required to register a signature
(authentication of the signer rely on the knowledge of his secret identifier and OTP, or on the control of his public key).
400Invalid request. More details are returned in the response body as a JSON object.
401Unauthorized. The signer is not an authorized signer (public key or secret signer identifier not found, or invalid OTP).
402Insufficient credits. The owner of the signature request runs out of signature or anchoring credit.
403Forbidden. The signature request is not in progress, the maximum number of signatures has been reached or the OTP has expired.
404Signature request not found.
409Conflict. The signer has already signed.
429Too many requests. A minimum delay of 1 second is required after providing an invalid OTP.
