Section 4.1 mentions three methods for securing information: prevention, restriction, and encryption. An alternate implementation splits data into separate pieces so that no single person holds all...

Section 4.1 mentions three methods for securing information: prevention,

restriction, and encryption. An alternate implementation splits data into

separate pieces so that no single person holds all the pieces. For example, a

safe may need three keys held by three different people. Is splitting information a form of prevention or restriction? Or is it a fourth option? If it is

a fourth option, are there other options (a fifth or sixth)?