com.entrust.toolkit.util

Class CmpRfc4210CompliantHasher

java.lang.Object

com.entrust.toolkit.util.CmpRfc4210CompliantHasher

public class CmpRfc4210CompliantHasher
extends java.lang.Object

This hasher implements the hashing specified in RFC 4210 section 5.1.3.1. It hashes the input the given number of times using the provided algorithm. If the key size is greater than the hash, the result is created by:

1. hash (now called BASEKEY) forms the high order bits
2. the BASEKEY (original hash) is prefixed with an ASCII block# (starting at 1) and then hashed with the same algorithm as above and appended
3. This is repeated until at least as big as the key size.
4. If the hash is bigger than the key size, it is truncated to the key size.

Constructor Summary

Constructors

Constructor and Description
CmpRfc4210CompliantHasher(java.security.MessageDigest messageDigest) A constructor; creates and initializes an CMP4210Hasher object that uses the provided MessageDigest to do the hashing.
CmpRfc4210CompliantHasher(java.security.MessageDigest messageDigest, byte[] input) A constructor; creates and initializes an CMP4210Hasher object that uses the provided MessageDigest to do the hashing.
CmpRfc4210CompliantHasher(java.lang.String algorithm) A constructor; creates and initializes an ExtendedHasher object that uses the specified hashing algorithm to do the hashing.
CmpRfc4210CompliantHasher(java.lang.String algorithm, byte[] input) A constructor; creates and initializes an ExtendedHasher object that uses the specified hashing algorithm to do the hashing.

Method Summary

Modifier and Type	Method and Description
byte[]	getOutput(int nIterations) Hashes the input byte array the specified number of times.
byte[]	getOutput(int requiredKeySize, int nIterations) Hashes the input byte array the specified number of times and returns the requested number of bytes (requiredKeySize), truncating or stretching the key as required.
void	setInput(byte[] input) Sets the input byte array to be used by the extended hasher, and resets all internal data in preparation for a new hashing session.
void	wipe() Wipes all internal data.

Methods inherited from class java.lang.Object

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

Constructor Detail

CmpRfc4210CompliantHasher

public CmpRfc4210CompliantHasher(java.lang.String algorithm)
                          throws java.security.NoSuchAlgorithmException

A constructor; creates and initializes an ExtendedHasher object that uses the specified hashing algorithm to do the hashing.

Parameters:

algorithm - the hashing algorithm

Throws:

java.security.NoSuchAlgorithmException - thrown if the hashing algorithm is not recognized

CmpRfc4210CompliantHasher

public CmpRfc4210CompliantHasher(java.lang.String algorithm,
                                 byte[] input)
                          throws java.security.NoSuchAlgorithmException

A constructor; creates and initializes an ExtendedHasher object that uses the specified hashing algorithm to do the hashing.

Parameters:

algorithm - the hashing algorithm

input - data to hash

Throws:

java.security.NoSuchAlgorithmException - thrown if the hashing algorithm is not recognized

CmpRfc4210CompliantHasher

public CmpRfc4210CompliantHasher(java.security.MessageDigest messageDigest,
                                 byte[] input)
                          throws java.lang.IllegalArgumentException

A constructor; creates and initializes an CMP4210Hasher object that uses the provided MessageDigest to do the hashing.

Parameters:

messageDigest - a MessageDigest that will be used for all hashing

input - data to hash

Throws:

java.lang.IllegalArgumentException - thrown if either parameter is null or the input is empty.

CmpRfc4210CompliantHasher

public CmpRfc4210CompliantHasher(java.security.MessageDigest messageDigest)

A constructor; creates and initializes an CMP4210Hasher object that uses the provided MessageDigest to do the hashing.

Parameters:

messageDigest - a MessageDigest that will be used for all hashing

Throws:

java.lang.IllegalArgumentException - thrown if either parameter is null or the input is empty.

Method Detail

setInput

public void setInput(byte[] input)
              throws java.lang.IllegalArgumentException

Sets the input byte array to be used by the extended hasher, and resets all internal data in preparation for a new hashing session.

Parameters:

input - the input byte array

Throws:

java.lang.IllegalArgumentException - thrown if the input byte array is null

getOutput

public byte[] getOutput(int nIterations)
                 throws java.lang.IllegalArgumentException,
                        java.lang.NullPointerException

Hashes the input byte array the specified number of times.

Parameters:

nIterations - the number of times to hash the input

Returns:

the hashed result

Throws:

java.lang.IllegalArgumentException - thrown if the requested number of bytes is less than zero, or if the requested number of iterations is less than one (at least one hashing round must be done)

java.lang.NullPointerException - thrown if the input data has not been set yet

getOutput

public byte[] getOutput(int requiredKeySize,
                        int nIterations)
                 throws java.lang.IllegalArgumentException,
                        java.lang.NullPointerException

Hashes the input byte array the specified number of times and returns the requested number of bytes (requiredKeySize), truncating or stretching the key as required.

The input is hashed nIterations times. The output of the final iteration (called "BASEKEY" for ease of reference, with a size of "H") is what is used to form the symmetric key. If the MAC algorithm requires a K-bit key and K <= H: the most significant K bits of BASEKEY are used. K > H: all of BASEKEY is used for the most significant H bits of the key, OWF("1" || BASEKEY) is used for the next most significant H bits of the key, OWF("2" || BASEKEY) is used for the next most significant H bits of the key, and so on, until all K bits have been derived.

Parameters:

requiredKeySize - the required key size, in bytes, or 0 if a specific key size isn't required. See RFC 4210 section 5.1.3.1 where this corresponds to 'K' but in bytes instead of bits.

nIterations - the number of times to hash the input

Returns:

the hashed result truncated or stretched as required.

Throws:

java.lang.IllegalArgumentException - thrown if the requested number of bytes is less than zero, or if the requested number of iterations is less than one (at least one hashing round must be done)

java.lang.NullPointerException - thrown if the input data has not been set yet

wipe

public final void wipe()

Wipes all internal data.