A Blockchain-Based User Authentication Scheme with Access Control for Telehealth Systems

Algorithm 2

Challenge-response pair contract.

	function uploadCRP(, , , , )
	if userExists  = = false
	status = ‘valid’
	= time.Now()
	user = User \{, , , , , status\}
	return putState(, user)
	else
	return Errorf(“the user has already exists”)
	function queryCRP
	err, result = getState
	if (err = = null && result.getStatus() = = ‘valid’)
	return result
	else if (result.getStatus() ! = “valid”)
	return Errorf(“the CRP of user has been expired”)
	return err
	function updateCRP(, , , )
	if userExists  = = true
	status = ‘valid’
	= time.Now()
	user = User \{, , , , , status\}
	return putState(, user)
	else
	return Errorf(“the user does not exist”)