org.bitcoinj.crypto

Class HDKeyDerivation

java.lang.Object

org.bitcoinj.crypto.HDKeyDerivation

public final class HDKeyDerivation
extends Object

Implementation of the BIP 32 deterministic wallet child key generation algorithm.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	HDKeyDerivation.PublicDeriveMode
static class	HDKeyDerivation.RawKeyBytes

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_CHILD_DERIVATION_ATTEMPTS Child derivation may fail (although with extremely low probability); in such case it is re-attempted.

Method Summary

Modifier and Type	Method and Description
static DeterministicKey	createMasterPrivateKey(byte[] seed) Generates a new deterministic key from the given seed, which can be any arbitrary byte array.
static DeterministicKey	createMasterPrivKeyFromBytes(byte[] privKeyBytes, byte[] chainCode)
static DeterministicKey	createMasterPubKeyFromBytes(byte[] pubKeyBytes, byte[] chainCode)
static DeterministicKey	deriveChildKey(DeterministicKey parent, ChildNumber childNumber)
static DeterministicKey	deriveChildKey(DeterministicKey parent, int childNumber) Derives a key given the "extended" child number, ie.
static HDKeyDerivation.RawKeyBytes	deriveChildKeyBytesFromPrivate(DeterministicKey parent, ChildNumber childNumber)
static HDKeyDerivation.RawKeyBytes	deriveChildKeyBytesFromPublic(DeterministicKey parent, ChildNumber childNumber, HDKeyDerivation.PublicDeriveMode mode)
static DeterministicKey	deriveThisOrNextChildKey(DeterministicKey parent, int childNumber) Derives a key of the "extended" child number, ie.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_CHILD_DERIVATION_ATTEMPTS

public static final int MAX_CHILD_DERIVATION_ATTEMPTS

Child derivation may fail (although with extremely low probability); in such case it is re-attempted. This is the maximum number of re-attempts (to avoid an infinite loop in case of bugs etc.).

See Also:

Constant Field Values

Method Detail

createMasterPrivateKey

public static DeterministicKey createMasterPrivateKey(byte[] seed)
                                               throws HDDerivationException

Generates a new deterministic key from the given seed, which can be any arbitrary byte array. However resist the temptation to use a string as the seed - any key derived from a password is likely to be weak and easily broken by attackers (this is not theoretical, people have had money stolen that way). This method checks that the given seed is at least 64 bits long.

Throws:

HDDerivationException - if generated master key is invalid (private key 0 or >= n).

IllegalArgumentException - if the seed is less than 8 bytes and could be brute forced.

createMasterPrivKeyFromBytes

public static DeterministicKey createMasterPrivKeyFromBytes(byte[] privKeyBytes,
                                                            byte[] chainCode)
                                                     throws HDDerivationException

Throws:

HDDerivationException - if privKeyBytes is invalid (0 or >= n).

createMasterPubKeyFromBytes

public static DeterministicKey createMasterPubKeyFromBytes(byte[] pubKeyBytes,
                                                           byte[] chainCode)

deriveChildKey

public static DeterministicKey deriveChildKey(DeterministicKey parent,
                                              int childNumber)

Derives a key given the "extended" child number, ie. the 0x80000000 bit of the value that you pass for childNumber will determine whether to use hardened derivation or not. Consider whether your code would benefit from the clarity of the equivalent, but explicit, form of this method that takes a ChildNumber rather than an int, for example: deriveChildKey(parent, new ChildNumber(childNumber, true)) where the value of the hardened bit of childNumber is zero.

deriveThisOrNextChildKey

public static DeterministicKey deriveThisOrNextChildKey(DeterministicKey parent,
                                                        int childNumber)

Derives a key of the "extended" child number, ie. with the 0x80000000 bit specifying whether to use hardened derivation or not. If derivation fails, tries a next child.

deriveChildKey

public static DeterministicKey deriveChildKey(DeterministicKey parent,
                                              ChildNumber childNumber)
                                       throws HDDerivationException

Throws:

HDDerivationException - if private derivation is attempted for a public-only parent key, or if the resulting derived key is invalid (eg. private key == 0).

deriveChildKeyBytesFromPrivate

public static HDKeyDerivation.RawKeyBytes deriveChildKeyBytesFromPrivate(DeterministicKey parent,
                                                                         ChildNumber childNumber)
                                                                  throws HDDerivationException

Throws:

HDDerivationException

deriveChildKeyBytesFromPublic

public static HDKeyDerivation.RawKeyBytes deriveChildKeyBytesFromPublic(DeterministicKey parent,
                                                                        ChildNumber childNumber,
                                                                        HDKeyDerivation.PublicDeriveMode mode)
                                                                 throws HDDerivationException

Throws:

HDDerivationException