org.whispersystems.libsignal.util

Class KeyHelper

java.lang.Object

org.whispersystems.libsignal.util.KeyHelper

public class KeyHelper
extends java.lang.Object

Helper class for generating keys of different types.

Method Summary

Modifier and Type	Method and Description
static IdentityKeyPair	generateIdentityKeyPair() Generate an identity key pair.
static java.util.List<PreKeyRecord>	generatePreKeys(int start, int count) Generate a list of PreKeys.
static int	generateRegistrationId(boolean extendedRange) Generate a registration ID.
static byte[]	generateSenderKey()
static int	generateSenderKeyId()
static ECKeyPair	generateSenderSigningKey()
static SignedPreKeyRecord	generateSignedPreKey(IdentityKeyPair identityKeyPair, int signedPreKeyId) Generate a signed PreKey
static int	getRandomSequence(int max)

Methods inherited from class java.lang.Object

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

Method Detail

generateIdentityKeyPair

public static IdentityKeyPair generateIdentityKeyPair()

Generate an identity key pair. Clients should only do this once, at install time.

Returns:

the generated IdentityKeyPair.

generateRegistrationId

public static int generateRegistrationId(boolean extendedRange)

Generate a registration ID. Clients should only do this once, at install time.

Parameters:

extendedRange - By default (false), the generated registration ID is sized to require the minimal possible protobuf encoding overhead. Specify true if the caller needs the full range of MAX_INT at the cost of slightly higher encoding overhead.

Returns:

the generated registration ID.

getRandomSequence

public static int getRandomSequence(int max)

generatePreKeys

public static java.util.List<PreKeyRecord> generatePreKeys(int start,
                                                           int count)

Generate a list of PreKeys. Clients should do this at install time, and subsequently any time the list of PreKeys stored on the server runs low.

PreKey IDs are shorts, so they will eventually be repeated. Clients should store PreKeys in a circular buffer, so that they are repeated as infrequently as possible.

Parameters:

start - The starting PreKey ID, inclusive.

count - The number of PreKeys to generate.

Returns:

the list of generated PreKeyRecords.

generateSignedPreKey

public static SignedPreKeyRecord generateSignedPreKey(IdentityKeyPair identityKeyPair,
                                                      int signedPreKeyId)
                                               throws InvalidKeyException

Generate a signed PreKey

Parameters:

identityKeyPair - The local client's identity key pair.

signedPreKeyId - The PreKey id to assign the generated signed PreKey

Returns:

the generated signed PreKey

Throws:

InvalidKeyException - when the provided identity key is invalid

generateSenderSigningKey

public static ECKeyPair generateSenderSigningKey()

generateSenderKey

public static byte[] generateSenderKey()

generateSenderKeyId

public static int generateSenderKeyId()