org.protelis.vm.impl

Class HashingCodePathFactory

java.lang.Object

org.protelis.vm.impl.HashingCodePathFactory

All Implemented Interfaces:

java.io.Serializable, CodePathFactory

public class HashingCodePathFactory
extends java.lang.Object
implements CodePathFactory

A hash-based CodePath factory. It allows for predictable packet sizes, as codepath length is no affected by the evaluation tree depth at which the field was built. It is arguably more secure than the default option (if a cryptographic hashing function is used) as receivers cannot deduce the code that generated some values. The provided factory is configurable by using an HashFunction from Guava. Being hash based, it has a non-zero probability of collision. Using decent hash functions (e.g. SHA) should however make the event very unlikely. In any case, there is a trade-off between collision probability and packet size. Implementations of AbstractExecutionContext can use it by passing the factory instance in the super constructor call, e.g.:

 super(execenv, netmgr, new HashingCodePathFactory(Hashing.sha256()));
 

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	HashingCodePathFactory.HasherSupplier Serializable supplier, because Java 8 lambdas are not.
static class	HashingCodePathFactory.HashingCodePath Hash-based CodePath.

Constructor Summary

Constructors

Constructor and Description
HashingCodePathFactory(com.google.common.hash.HashFunction hashFunction)
HashingCodePathFactory(HashingCodePathFactory.HasherSupplier hashFunction)

Method Summary

Modifier and Type	Method and Description
CodePath	createCodePath(gnu.trove.list.TIntList callStackIdentifiers, gnu.trove.stack.TIntStack callStackSizes) Creates a CodePath for the current stack status.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HashingCodePathFactory

public HashingCodePathFactory(HashingCodePathFactory.HasherSupplier hashFunction)

Parameters:

hashFunction - the hashing algorithm to use

HashingCodePathFactory

public HashingCodePathFactory(com.google.common.hash.HashFunction hashFunction)

Parameters:

hashFunction - the hashing algorithm to use

Method Detail

createCodePath

public final CodePath createCodePath(gnu.trove.list.TIntList callStackIdentifiers,
                                     gnu.trove.stack.TIntStack callStackSizes)

Description copied from interface: CodePathFactory

Creates a CodePath for the current stack status.

Specified by:

createCodePath in interface CodePathFactory

Parameters:

callStackIdentifiers - the stack frames identifiers

callStackSizes - the stack frame sizes, by frame

Returns:

a new CodePath