com.google.crypto.tink.subtle.prf

Class PrfImpl

java.lang.Object

com.google.crypto.tink.subtle.prf.PrfImpl

All Implemented Interfaces:

Prf

@Immutable
public class PrfImpl
extends Object
implements Prf

Class that implements the Prf primitive by wrapping a StreamingPrf.

Method Summary

Modifier and Type	Method and Description
byte[]	compute(byte[] input, int outputLength) Computes the PRF selected by the underlying key on input and returns the first outputLength bytes.
static PrfImpl	wrap(StreamingPrf prfStreamer) Creates a Prf primitive from a StreamingPrf primitive.

Methods inherited from class java.lang.Object

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

Method Detail

wrap

public static PrfImpl wrap(StreamingPrf prfStreamer)

Creates a Prf primitive from a StreamingPrf primitive.

compute

public byte[] compute(byte[] input,
                      int outputLength)
               throws GeneralSecurityException

Description copied from interface: Prf

Computes the PRF selected by the underlying key on input and returns the first outputLength bytes.

Specified by:

compute in interface Prf

Parameters:

input - the input to compute the PRF on.

outputLength - the desired length of the output in bytes. When choosing this parameter keep the birthday paradox in mind. If you have 2^n different inputs that your system has to handle set the output length to ceil(n/4 + 4) This corresponds to 2*n + 32 bits, meaning a collision will occur with a probability less than 1:2^32. When in doubt, request a security review.

Throws:

GeneralSecurityException - if the algorithm fails or if the output of algorithm is less than outputLength.