de.uni_koblenz.aggrimm.icp.crypto.sign.algorithm.auxiliary

Class HashCombinator

java.lang.Object

de.uni_koblenz.aggrimm.icp.crypto.sign.algorithm.auxiliary.HashCombinator

public class HashCombinator
extends Object

Combine hashes There are 3 possible combination algorithms: Method Speed Security --------------------------------------------------------------------- - Xor fast low - Addition modulo N average average - Multiplication modulo N slow high

Author:

Peter Schauß

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	HashCombinator.ca

Field Summary

Fields

Modifier and Type	Field and Description
static BigInteger	N_ADD
static BigInteger	N_MUL Modulo Number 64-bit prime: 2^64 - 59 = 18446744073709551557 BigInteger("2").pow(64).subtract(new BigInteger("59")); 3072-bit prime: 2^3072 - 1103717 BigInteger("2").pow(3072).subtract(new BigInteger("1103717")); 2048-bit prime: 2^2048 - 11837 BigInteger("2").pow(2048).subtract(new BigInteger("11837"));
static BigInteger	N_XOR

Constructor Summary

Constructors

Constructor and Description
HashCombinator()

Method Summary

Modifier and Type	Method and Description
static BigInteger	combine(BigInteger a, BigInteger b, HashCombinator.ca algorithm) Combines two BigInteger hashes (requires no conversion from/to byte[])
static byte[]	combine(byte[] hashA, byte[] hashB, HashCombinator.ca algorithm) Combines two byte[] hashes

Methods inherited from class java.lang.Object

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

Field Detail

N_MUL

public static final BigInteger N_MUL

Modulo Number 64-bit prime: 2^64 - 59 = 18446744073709551557 BigInteger("2").pow(64).subtract(new BigInteger("59")); 3072-bit prime: 2^3072 - 1103717 BigInteger("2").pow(3072).subtract(new BigInteger("1103717")); 2048-bit prime: 2^2048 - 11837 BigInteger("2").pow(2048).subtract(new BigInteger("11837"));

N_XOR

public static final BigInteger N_XOR

N_ADD

public static final BigInteger N_ADD

Constructor Detail

HashCombinator

public HashCombinator()

Method Detail

combine

public static byte[] combine(byte[] hashA,
                             byte[] hashB,
                             HashCombinator.ca algorithm)

Combines two byte[] hashes

Parameters:

hashA - first hash value to combine

hashB - second hash value to combine

algorithm - used combination algorithm (HashCombinator.ca)

Returns:

combined hash value as byte array

combine

public static BigInteger combine(BigInteger a,
                                 BigInteger b,
                                 HashCombinator.ca algorithm)

Combines two BigInteger hashes (requires no conversion from/to byte[])

Parameters:

a - first hash value to combine

b - second hash value to combine

algorithm - used combination algorithm (HashCombinator.ca)

Returns:

combined hash value as BigInteger