As we have seen in the previous article, the blockchain lends itself to tracing transactions between two subjects, but to respond to this need, it would not be enough to have a simpler communication protocol based on known tools such as
- Digital signature for imputability,
- Certified delivery receipt
- Timestamp for the time guarantee?
In particular, would not a mechanism based on the return receipt, typical of the postal system, be sufficient?
In other words what is the function of the “log” within a communication protocol?
Communication is a process of processing, transmitting and receiving messages and follows a linear model in which:
A subject (sender) processes a message according to a code, sends it through a channel to the receiving recipient and decodes it.
In this system the sender, if he receives a return receipt, is guaranteed the delivery, but the recipient has no guarantee that the sender has in turn received the notification of the return receipt, so he does not know if the sender is notified or not Of receiving the message. In fact, to have that security it should send and receive a new message from the sender; But in this way the sender would not be more confident that the recipient would receive confirmation of the confirmation.
One of the paradoxes of communication opens therefore, which cannot be used with subsequent confirmation messages, which would otherwise be repeated indefinitely.
To overcome this in a conventional way, only the sender, through the return receipt, has information on receiving the message from the recipient, of course with all the legal consequences associated with that choice: for example in the Italian legal system the so-called presumption of knowledge, whereby communications directed to a particular subject are considered known at the time they reach the address of the recipient, terminates the notifications chain at the moment the sender has received the confirmation that the message has arrived at the address of the recipient, if the recipient does not read the mail … it’s his problem, but the communication is legally successful.
In order to overcome this intrinsic limitation of the communication protocol, especially when it is necessary that not only the affected parties but also other parties can know the status of a transaction, there is a need for a log to collect the transactions, which can be consulted by the sender from the recipient and eventually from the so-called interested third parties, and determine, in case of disputes, whether it is to be faithful.
When the transaction is of particular relevance to the legal order it is placed under the supervision and management of a public entity by the creation of a public register; but even if the transaction is of relevance only among private individuals, the creation of a register can meet this need for knowledge and the implementation of blockchain mechanisms is useful to the creation of computer registers.
Traceability of transactions through public registers
Public registers are nothing more than centralized databases of certain transactions that must be registered in them, managed under the responsibility and control of an entity subject to a rule.
They allow, in relation to their function, the traceability of specific information / operations.
The function of public registers and the manner in which they are held are always defined by a law (subjects authorized to modify and consult registers, access rights, security criteria and quality of service) and their relevance goes beyond those directly concerned from the transaction; the specificity of the public registry is to have the value:
For third parties not involved in the transaction, which can therefore legally rely on the results of the public register
For the State that always based on these findings it bases some tax claims but also of liability in the field of publicity and criminal (think about road traffic and how to determine the ownership of vehicles).
Traceability of transactions by blockchain mechanisms
The need to have a mechanism for registering transactions, which is not subject to an entity in this way, simplifies two different strategies:
Entities agree in a formal way for one of them to handle the register on behalf of everyone (centralized system);
Entities handle distributed (distributed) system records.
The blockchain system is born as a distributed database system where the guarantee of registration is guaranteed by the fact that multiple systems report consistently on registering the transaction; more exactly whenever you want to register a transaction, the confirmation that it has been validated must come from at least 51% of the nodes participating in the network.
The guarantee of non-modification of the registers is given both by the number of coherent log replicas and by encryption systems. Various applications that need logs for traceability of transactions can leverage this mechanism by honing the following features:
Plurality of different subjects, better if they are extraneous to the transaction to be traced, which handle copies of the logs for reliability and security in case of failures (management computer systems should be in different locations). These subjects may possibly be networked in a qualified network, but must in any case be different to ensure the distribution of information and the ability to handle separate replies;
Registry volunteering: The registers to be managed must be voluntary, that is, they are not under the control and management of a single entity defined by a rule, otherwise we would fall into the central register scheme.
Systems based on these features in practice recognize the usefulness of having a register of transactions that can be consulted by the interested parties and by third parties, but instead replace the public register managed by a qualified body to that effect, a register managed in a distributed manner by subjects who can, they do not necessarily have to, have different qualifications, so they can also be private entities with great computing power.
The network of subjects managing log replies can in principle be open or qualified as we will see in the next deepening.