JVM TCB: Measurements of the Trusted Computing Base of Java Virtual Machines

Abstract:

The trusted computing base (TCB) of a Java virtual machine (JVM)
is the part of the program code in which programming bugs
could lead to security holes. Java systems keep the front
end compiler (which translates source code to byte code) out of
the TCB, by having the JVM verify the safety of the byte code
before just-in-time (JIT) compiling it to machine code. Still,
the JIT compiler itself is usually in the TCB, and the more lines
of code in the TCB, the more likelihood of security problems.
We have measured the TCB size of several JVMs, and find that they
range from 36,000 to 229,000 lines of source code.