Книга: Code 2.0

Identity and Authentication: Cyberspace

Identity and Authentication: Cyberspace

Identity and authentication in cyberspace and real space are in theory the same. In practice they are quite different. To see that difference, however, we need to see more about the technical detail of how the Net is built.

As I’ve already said, the Internet is built from a suite of protocols referred to collectively as “TCP/IP.” At its core, the TCP/IP suite includes protocols for exchanging packets of data between two machines “on” the Net.[2] Brutally simplified, the system takes a bunch of data (a file, for example), chops it up into packets, and slaps on the address to which the packet is to be sent and the address from which it is sent. The addresses are called Internet Protocol addresses, and they look like this: 128.34.35.204. Once properly addressed, the packets are then sent across the Internet to their intended destination. Machines along the way (“routers”) look at the address to which the packet is sent, and depending upon an (increasingly complicated) algorithm, the machines decide to which machine the packet should be sent next. A packet could make many “hops” between its start and its end. But as the network becomes faster and more robust, those many hops seem almost instantaneous.

In the terms I’ve described, there are many attributes that might be associated with any packet of data sent across the network. For example, the packet might come from an e-mail written by Al Gore. That means the e-mail is written by a former vice president of the United States, by a man knowledgeable about global warming, by a man over the age of 50, by a tall man, by an American citizen, by a former member of the United States Senate, and so on. Imagine also that the e-mail was written while Al Gore was in Germany, and that it is about negotiations for climate control. The identity of that packet of information might be said to include all these attributes.

But the e-mail itself authenticates none of these facts. The e-mail may say it’s from Al Gore, but the TCP/IP protocol alone gives us no way to be sure. It may have been written while Gore was in Germany, but he could have sent it through a server in Washington. And of course, while the system eventually will figure out that the packet is part of an e-mail, the information traveling across TCP/IP itself does not contain anything that would indicate what the content was. The protocol thus doesn’t authenticate who sent the packet, where they sent it from, and what the packet is. All it purports to assert is an IP address to which the packet is to be sent, and an IP address from which the packet comes. From the perspective of the network, this other information is unnecessary surplus. Like a daydreaming postal worker, the network simply moves the data and leaves its interpretation to the applications at either end.

This minimalism in the Internet’s design was not an accident. It reflects a decision about how best to design a network to perform a wide range over very different functions. Rather than build into this network a complex set of functionality thought to be needed by every single application, this network philosophy pushes complexity to the edge of the network — to the applications that run on the network, rather than the network’s core. The core is kept as simple as possible. Thus if authentication about who is using the network is necessary, that functionality should be performed by an application connected to the network, not by the network itself. Or if content needs to be encrypted, that functionality should be performed by an application connected to the network, not by the network itself.

This design principle was named by network architects Jerome Saltzer, David Clark, and David Reed as the end-to-end principle[3]. It has been a core principle of the Internet’s architecture, and, in my view, one of the most important reasons that the Internet produced the innovation and growth that it has enjoyed. But its consequences for purposes of identification and authentication make both extremely difficult with the basic protocols of the Internet alone. It is as if you were in a carnival funhouse with the lights dimmed to darkness and voices coming from around you, but from people you do not know and from places you cannot identify. The system knows that there are entities out there interacting with it, but it knows nothing about who those entities are. While in real space — and here is the important point — anonymity has to be created, in cyberspace anonymity is the given.

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