More than the structure of the blockchain, it is the extreme redundancy of the main file and the operations of construction of this file which is the most striking originality of Bitcoin and the systems that derive from it. A computer application that uses the same file structure, but is implemented on a single computer or a small number of computers belonging to related organizations, would obviously not have the same properties.

This redundancy ensures 24-hour service continuity. Each computer can disconnect or fail without jeopardizing the proper functioning of the entire system. If it is a complete node, the blockchain build protocol will automatically rebuild the missing portion with the help of neighboring nodes when it becomes operational again.

As long as he has access to the Internet, a user will always find a network node to accept and relay a write, and there will be a large number of miners and full nodes to register and make it available in their blockchain . All scripts, even those created in a country where no Bitcoin network node exists, will be processed by computers anywhere in the world, and will be readable anywhere in the world with access to the Internet. The only way to shutdown the system is to shut down the Internet.


This same redundancy, coupled with the “precautionary principle” according to which each node of the network verifies the validity of everything it receives before using it, makes it impossible to propagate fraudulent entries. All errors and frauds are possible on a particular computer, whether by the site operator or by a hacker who manipulates this site. It is even possible that they spread locally through contagion or connivance. But it is almost impossible for this pollution to spread to a significant percentage of the blockchain, let alone the entire network.

On the other hand, any device whose functions are not duplicated in the network remains vulnerable. This is particularly the case for individual keyrings, which hold the correspondence between the account numbers and the identity of their holders, and systems serving as an entry / exit portal, for example the exchange sites with the others. currencies or interconnection with corporate IT. The security and confidentiality of these peripheral systems are the responsibility of their operators. Hack a walletor an exchange site can have dramatic consequences for their users (this is the only way to “steal” bitcoins), but has no effect on the Bitcoin system itself, in the same way as stealing the wallet. someone does not endanger the banking system. When we stop the activities of an illicit trading platform such as Silk Road, it is all the same as if we were dismantling a mafia; Contrary to what is often read in the press, the Bitcoin system itself is better off.