HKDFBytesGenerator (Bouncy Castle Cryptography 1.79 API Specification)

java.lang.Object
- org.bouncycastle.crypto.generators.HKDFBytesGenerator

All Implemented Interfaces:

DerivationFunction
```
public class HKDFBytesGenerator
extends java.lang.Object
implements DerivationFunction
```
HMAC-based Extract-and-Expand Key Derivation Function (HKDF) implemented according to IETF RFC 5869, May 2010 as specified by H. Krawczyk, IBM Research & P. Eronen, Nokia. It uses a HMac internally to compute de OKM (output keying material) and is likely to have better security properties than KDF's based on just a hash function.

Constructor Summary

Constructors
Constructor Description

HKDFBytesGenerator(Digest hash)
Creates a HKDFBytesGenerator based on the given hash function.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`byte[]`	`extractPRK(byte[] salt, byte[] ikm)`	Performs the extract part of the key derivation function.
`int`	`generateBytes(byte[] out, int outOff, int len)`
`Digest`	`getDigest()`
`void`	`init(DerivationParameters param)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - HKDFBytesGenerator
```
public HKDFBytesGenerator(Digest hash)
```
    Creates a HKDFBytesGenerator based on the given hash function.
    
    Parameters:
    
    hash - the digest to be used as the source of generatedBytes bytes
- Method Detail
  - init
```
public void init(DerivationParameters param)
```
    Specified by:
    
    init in interface DerivationFunction
  - extractPRK
```
public byte[] extractPRK(byte[] salt,
                         byte[] ikm)
```
    Performs the extract part of the key derivation function.
    
    Parameters:
    
    salt - the salt to use
    
    ikm - the input keying material
    
    Returns:
    
    the PRK as KeyParameter
  - getDigest
```
public Digest getDigest()
```
  - generateBytes
```
public int generateBytes(byte[] out,
                         int outOff,
                         int len)
                  throws DataLengthException,
                         java.lang.IllegalArgumentException
```
    Specified by:
    
    generateBytes in interface DerivationFunction
    
    Throws:
    
    DataLengthException
    
    java.lang.IllegalArgumentException