net.i2p.router.crypto.ratchet

Class Elligator2

java.lang.Object

net.i2p.router.crypto.ratchet.Elligator2

class Elligator2
extends Object

Elligator2 encoding and decoding for X25519 public keys to provide cryptographically indistinguishable representations Ported from the Jan. 13, 2016 C version at https://github.com/Kleshni/Elligator-2 Note: That code was completely rewritten May 8, 2017 and is now much more complex. No apparent license.

Constructor Summary

Constructors

Constructor and Description
Elligator2(I2PAppContext ctx)

Method Summary

Modifier and Type	Method and Description
static PublicKey	decode(AtomicBoolean alternative, byte[] representative) From javascript version documentation: Returns an array with the point and the second argument of the corresponding call to the `encode` function.
static PublicKey	decode(byte[] representative) From javascript version documentation: Returns an array with the point and the second argument of the corresponding call to the `encode` function.
byte[]	encode(PublicKey point) Use for on-the-wire.

Methods inherited from class java.lang.Object

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

Constructor Detail

Elligator2

public Elligator2(I2PAppContext ctx)

Method Detail

decode

public static PublicKey decode(AtomicBoolean alternative,
                               byte[] representative)

From javascript version documentation: Returns an array with the point and the second argument of the corresponding call to the `encode` function. It's also able to return null if the representative is invalid (there are only 10 invalid representatives).

Parameters:

alternative - out parameter, or null if you don't care

representative - the encoded data, little endian, 32 bytes; WILL BE MODIFIED by masking byte 31

Returns:

x or null on failure

decode

public static PublicKey decode(byte[] representative)

From javascript version documentation: Returns an array with the point and the second argument of the corresponding call to the `encode` function. It's also able to return null if the representative is invalid (there are only 10 invalid representatives).

Parameters:

representative - the encoded data, little endian, 32 bytes WILL BE MODIFIED by masking byte 31

Returns:

x or null on failure

encode

public byte[] encode(PublicKey point)

Use for on-the-wire. Don't use for unit tests as output will be randomized based on the 'alternative' and the high bits. There are eight possible encodings for any point. Output will look like 256 random bits.

Returns:

"representative", little endian or null on failure