A Fortress Built on Sand

There are two strategies that I know for building robust systems on top of less robust systems,
John von Neumann described in the 40’s a scheme for building reliable digital computing equipment from unreliable parts. Twenty years later Hamming codes were invented to extend this idea but that was still in von Neumann’s general plan. RAM can now be built that is much more reliable than even the reliable commodity parts that are now available.

Cryptography and hash ideas allow us build reliable channels to carry data upon unreliable channels. Here reliable means that the data will delivered to the correct place and no where else.

The second scheme assumes that there are opponents working against the designer whereas the first schemes assumes that nature is benign.