de.flexiprovider.core.kdf
Class X963

java.lang.Object
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  +--de.flexiprovider.api.KeyDerivation
        |
        +--de.flexiprovider.core.kdf.X963

public class X963

extends KeyDerivation

X963 is a key derivation function defined in ANSI X9.63.

X963 can be used as follows:

 KeyDerivation kdf = Registry.getKeyDerivation("X963");
 kdf.init(secretKey.toByteArray());
 kdf.setSharedInfo(byte[] sharedInfo);
 byte[] derivedKey = kdf.doFinal(int keyDataLen);
 

Author:

Jochen Hechler, Marcus Stögbauer, Martin Döring

Constructor Summary

X963()
Constructor.

Method Summary

byte[]	deriveKey(int keySize) This function does the actual key derivation.
void	init(byte[] secret, AlgorithmParameterSpec params) Initialize the KDF with a secret and parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

X963

public X963()

Constructor. Set the message digest.

Method Detail

init

public void init(byte[] secret,
                 AlgorithmParameterSpec params)
          throws InvalidKeyException,
                 InvalidAlgorithmParameterException

Initialize the KDF with a secret and parameters. The parameters have to be null or an instance of KDFParameterSpec.

Overrides:

init in class KeyDerivation

Parameters:

secret - the secret from which to derive the key

params - the parameters

Throws:

InvalidKeyException - if the secret is null.

InvalidAlgorithmParameterException - if the parameters are not null and not an instance of KDFParameterSpec.

deriveKey

public byte[] deriveKey(int keySize)

This function does the actual key derivation. It uses the shared key value Z from above and the given key size with the desired hash function H and the optional SharedInfo and computes

 Hash<sup>i</sup> = H(Z || counter || [SharedInfo])
 

where the counter is a 32 bit string.

Overrides:

deriveKey in class KeyDerivation

Parameters:

keySize - the desired length of the derived key

Returns:

the derived key with the specified length, or null if the key size is < 0.