iaik.security.kdf

Class KDF1

java.lang.Object

javax.crypto.KeyGeneratorSpi

iaik.security.kdf.KDF1

Direct Known Subclasses:

KDF2

public class KDF1
extends javax.crypto.KeyGeneratorSpi

This class implements the Key Derivation Function (KDF) 1, defined in ISO/IEC 18033-2. A KDF is a function which derives keying material of desired length from a shared secret and additional, optional information. The KDF itself is further parameterized with, e.g., a cryptographic hash function.

An application which wants to use KDF1 has to obtain it via the KeyGenerator engine class.

     KeyGenerator kdf1 = KeyGenerator.getInstance("KDF1", ""IAIK)
 

A caller has to configure the KDF1 with a cryptographic hash function, like SHA2-256, SHA3-256,.... For that, use KDF1ParameterSpec. An example usage may look like this:

     AlgorithmID hashAlg = ...;
     int keyLength = ...;
     byte[] secretValue = ...
     KDF1ParameterSpec spec = new KDF1ParameterSpec(hashAlg, keyLength);
     spec.setSecretValue(secretValue);
     kg.init(spec);
     SecretKey key = (SecretKey) kg.generateKey();
 

If an implementation tries to use the KDF1 without a call to engineInit(AlgorithmParameterSpec, SecureRandom), the class will throw an exception.

See Also:

KDF1ParameterSpec

Field Summary

Fields

Modifier and Type	Field and Description
static ObjectID	OID The ASN.1 object identifier (1.0.18033.2.5.1) for the KDF1 key derivation function.

Constructor Summary

Constructors

Constructor and Description
KDF1()

Method Summary

Methods

Modifier and Type	Method and Description
protected javax.crypto.SecretKey	engineGenerateKey() Generates a key according to the specification of KDF1 with the provided information.
protected void	engineInit(java.security.spec.AlgorithmParameterSpec paramSpec, java.security.SecureRandom random) Initializes the KDF1 with the provided AlgorithmParameterSpec.
protected void	engineInit(int keysize, java.security.SecureRandom random) This method is not supported as the caller has to initiate the class with a KDF1ParameterSpec.
protected void	engineInit(java.security.SecureRandom random) This method is not supported as the caller has to initiate the class with a KDF1ParameterSpec.
protected HashBasedGenerationFunction	generateHBGF(KDF1ParameterSpec spec) Intern helper function to create an instance of HashBasedGenerationFunction.
protected java.lang.String	name() Outputs the algorithm name.

Methods inherited from class java.lang.Object

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

Field Detail

OID

public static final ObjectID OID

The ASN.1 object identifier (1.0.18033.2.5.1) for the KDF1 key derivation function.

Constructor Detail

KDF1

public KDF1()

Method Detail

name

protected java.lang.String name()

Outputs the algorithm name. Will always return "KDF1".

Returns:

"KDF1"

generateHBGF

protected HashBasedGenerationFunction generateHBGF(KDF1ParameterSpec spec)

Intern helper function to create an instance of HashBasedGenerationFunction. Note: Do not call this on your own.

engineInit

protected void engineInit(java.security.SecureRandom random)

This method is not supported as the caller has to initiate the class with a KDF1ParameterSpec.

Specified by:

engineInit in class javax.crypto.KeyGeneratorSpi

engineInit

protected void engineInit(int keysize,
              java.security.SecureRandom random)

This method is not supported as the caller has to initiate the class with a KDF1ParameterSpec.

Specified by:

engineInit in class javax.crypto.KeyGeneratorSpi

engineInit

protected void engineInit(java.security.spec.AlgorithmParameterSpec paramSpec,
              java.security.SecureRandom random)
                   throws java.security.InvalidAlgorithmParameterException

Initializes the KDF1 with the provided AlgorithmParameterSpec. The implementation expects an instance of KDF1ParameterSpec. The method ignores the second parameter, as it does not need a source of randomness.

Specified by:

engineInit in class javax.crypto.KeyGeneratorSpi

Parameters:

paramSpec - an instance of AlgorithmParameterSpec

random - may be null as it will be ignored

Throws:

java.security.InvalidAlgorithmParameterException - if the caller provides AlgorithmParameterSpec which are inappropriate to initialize the object.

engineGenerateKey

protected javax.crypto.SecretKey engineGenerateKey()

Generates a key according to the specification of KDF1 with the provided information. This method returns an instance of SecretKey. To obtain the secret, call SecretKey.getEncoded().

Specified by:

engineGenerateKey in class javax.crypto.KeyGeneratorSpi

Returns:

an instance of SecretKey holding the derived secret.

Throws:

InternalErrorException - if the caller did not initialize the object accordingly.