Package nxt.crypto

Class KeyDerivation

java.lang.Object

nxt.crypto.KeyDerivation

public class KeyDerivation
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	KeyDerivation.Bip32Node	Represents a node in the Bip32 derivation tree.

Constructor Summary

Constructors

Constructor	Description
KeyDerivation()

Method Summary

Modifier and Type	Method	Description
static KeyDerivation.Bip32Node	deriveChildPrivateKey(KeyDerivation.Bip32Node node, int childIndex)	INPUT: (kL,kR): 64 bytes private eddsa key A: 32 bytes public key (y coordinate only), optional as A = kR.G (y coordinate only) c: 32 bytes chain code i: child index to compute (hardened if >= 0x80000000) OUTPUT: (kL_i,kR_i): 64 bytes ith-child private eddsa key A_i: 32 bytes ith-child public key, A_i = kR_i.G (y coordinatte only) c_i: 32 bytes ith-child chain code PROCESS: 1.
static KeyDerivation.Bip32Node	deriveChildPublicKey(byte[] parentPublicKey, byte[] chainCode, int childIndex)
static KeyDerivation.Bip32Node	deriveChildPublicKey(KeyDerivation.Bip32Node node, int childIndex)
static KeyDerivation.Bip32Node	deriveChildPublicKey(PublicKeyDerivationInfo derivationInfo)
static KeyDerivation.Bip32Node	deriveChildPublicKey(SerializedMasterPublicKey serializedMasterPublicKey, int childIndex)
static KeyDerivation.Bip32Node	deriveMnemonic(String path, String mnemonic)
static KeyDerivation.Bip32Node	deriveSeed(String path, byte[] seed)
static byte[]	mnemonicToSeed(String mnemonic)
static byte[]	mnemonicToSeed(String mnemonic, String passphrase)

Methods inherited from class java.lang.Object

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

Constructor Details

KeyDerivation

public KeyDerivation()

Method Details

deriveMnemonic

public static KeyDerivation.Bip32Node deriveMnemonic(String path,
 String mnemonic)

Parameters:

path - bip32 path

mnemonic - bip39 words

Returns:

derived seed

mnemonicToSeed

public static byte[] mnemonicToSeed(String mnemonic)

mnemonicToSeed

public static byte[] mnemonicToSeed(String mnemonic,
 String passphrase)

deriveSeed

public static KeyDerivation.Bip32Node deriveSeed(String path,
 byte[] seed)

Parameters:

path - bip32 string path to derive (eg 42'/1/2)

seed - 512 bits seed

Returns:

bip32 node representing the public/private key pair and chain code

deriveChildPublicKey

public static KeyDerivation.Bip32Node deriveChildPublicKey(PublicKeyDerivationInfo derivationInfo)

deriveChildPublicKey

public static KeyDerivation.Bip32Node deriveChildPublicKey(KeyDerivation.Bip32Node node,
 int childIndex)

deriveChildPublicKey

public static KeyDerivation.Bip32Node deriveChildPublicKey(SerializedMasterPublicKey serializedMasterPublicKey,
 int childIndex)

deriveChildPublicKey

public static KeyDerivation.Bip32Node deriveChildPublicKey(byte[] parentPublicKey,
 byte[] chainCode,
 int childIndex)

deriveChildPrivateKey

public static KeyDerivation.Bip32Node deriveChildPrivateKey(KeyDerivation.Bip32Node node,
 int childIndex)

INPUT:

• (kL,kR): 64 bytes private eddsa key
• A: 32 bytes public key (y coordinate only), optional as A = kR.G (y coordinate only)
• c: 32 bytes chain code
• i: child index to compute (hardened if >= 0x80000000)

OUTPUT:

• (kL_i,kR_i): 64 bytes ith-child private eddsa key
• A_i: 32 bytes ith-child public key, A_i = kR_i.G (y coordinatte only)
• c_i: 32 bytes ith-child chain code

PROCESS: 1. encode i 4-bytes little endian, il = encode_U32LE(i)
2. if i is less than 2^31
- compute Z = HMAC-SHA512(key=c, Data=0x02 | A | il )
- compute c_ = HMAC-SHA512(key=c, Data=0x03 | A | il )
else
- compute Z = HMAC-SHA512(key=c, Data=0x00 | kL | kR | il )
- compute c_ = HMAC-SHA512(key=c, Data=0x01 | kL | kR | il )
3. ci = lowest_32bytes(c_)
4. set ZL = highest_28bytes(Z)
set ZR = lowest_32bytes(Z)
5. compute kL_i:
zl_ = LEBytes_to_int(ZL)
kL_ = LEBytes_to_int(kL)
kLi_ = zl_*8 + kL_
if kLi_ % order == 0: child does not exist
kL_i = int_to_LEBytes(kLi_)
6. compute kR_i
zr_ = LEBytes_to_int(ZR)
kR_ = LEBytes_to_int(kR)
kRi_ = (zr_ + kRn_) % 2^256
kR_i = int_to_LEBytes(kRi_)
7. compute A
A = kLi_.G
8. return (kL_i,kR_i), A_i, c

Parameters:

node - node

childIndex - child index

Returns:

derived node