Package de.pseudonymisierung.controlnumbers

Class ControlNumberGenerator

java.lang.Object

de.pseudonymisierung.controlnumbers.ControlNumberGenerator

All Implemented Interfaces:

java.util.function.Function<String,ControlNumber>

Direct Known Subclasses:

EncryptedControlNumberGenerator

public class ControlNumberGenerator
extends Object
implements java.util.function.Function<String,ControlNumber>

Generator for "simple" control number, i.e. without encryption by a secret key. Use builder() to get a ControlNumberGenerator.Builder instance, which has methods for setting various parameters.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ControlNumberGenerator.AbstractBuilder<T extends ControlNumberGenerator>	Abstraction of a builder class.
static class	ControlNumberGenerator.Builder	Builder for simple control number generators (i.e.

Field Summary

Fields

Modifier and Type	Field	Description
static Charset	defaultEncoding	Default encoding to use when transforming input strings to byte sequences (necessery for applying hash functions and encryption).
static int	defaultHashLength	Default bit lenght of control numbers.
static int	defaultNGramLength	Default length of n-grams (2 -> bigrams).
static int	defaultNHashFunctions	Default number of hash functions.
protected Charset	encoding

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ControlNumberGenerator(ControlNumberGenerator.AbstractBuilder<?> builder)	Constructor, called by ControlNumberGenerator.Builder.build().

Method Summary

Modifier and Type	Method	Description
ControlNumber	apply(String input)	Calculate a control number from an input string.
static ControlNumberGenerator.Builder	builder()	Get a builder object with methods to set parameters to non-default values and to get the resulting instance of ControlNumberGenerator.
protected byte[]	getMd5Hash(String input)	Get MD5 hash of a string.
protected byte[]	getSha1Hash(String input)	Get SHA1 hash of a string.
protected int	hash(byte[] basehash1, byte[] baseHash2, int index)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Function

andThen, compose

Field Detail

defaultHashLength

public static final int defaultHashLength

Default bit lenght of control numbers.

See Also:

Constant Field Values

defaultNGramLength

public static final int defaultNGramLength

Default length of n-grams (2 -> bigrams).

See Also:

Constant Field Values

defaultNHashFunctions

public static final int defaultNHashFunctions

Default number of hash functions.

See Also:

Constant Field Values

defaultEncoding

public static final Charset defaultEncoding

Default encoding to use when transforming input strings to byte sequences (necessery for applying hash functions and encryption).

encoding

protected Charset encoding

Constructor Detail

ControlNumberGenerator

protected ControlNumberGenerator(ControlNumberGenerator.AbstractBuilder<?> builder)

Constructor, called by ControlNumberGenerator.Builder.build().

Parameters:

builder - The builder object from which to create the instance.

Method Detail

builder

public static ControlNumberGenerator.Builder builder()

Get a builder object with methods to set parameters to non-default values and to get the resulting instance of ControlNumberGenerator.

Returns:

An instance of ControlNumberGenerator.Builder

apply

public ControlNumber apply(String input)

Calculate a control number from an input string.

Specified by:

apply in interface java.util.function.Function<String,ControlNumber>

Parameters:

input - The character string to encode.

Returns:

The resulting control number.

getMd5Hash

protected byte[] getMd5Hash(String input)

Get MD5 hash of a string. This is one of the base hash functions from which the desired number of hashes is calculated. The base hashes are defined as protected methods so that EncryptedControlNumberGenerator only needs to override these using keyed hash functions.

Parameters:

input - The character string to encode.

Returns:

The resulting hash.

getSha1Hash

protected byte[] getSha1Hash(String input)

Get SHA1 hash of a string.

See Also:

for more information.

hash

protected int hash(byte[] basehash1,
                   byte[] baseHash2,
                   int index)