KeyDerivationService

Source

BIP-32/BIP-44 hierarchical deterministic key derivation.

Interface Bip44PathOptions:

Field	Type	Required	Description
coinType	number	Yes	BIP-44 coin type.
account	number	No	Account index. Defaults to 0.
change	number	No	0 = external chain, 1 = internal. Defaults to 0.
index	number	No	Address index. Defaults to 0.

buildBip44Path

buildBip44Path(options: Bip44PathOptions): string

Constructs a BIP-44 derivation path string from the provided options.

Parameters:

Name	Type	Required	Description
options	Bip44PathOptions	Yes	Path components (coinType, account, change, index).

Returns: string — derivation path in the format m/44'/coinType'/account'/change/index.

derivePrivateKey

derivePrivateKey(masterNode: BIP32Interface, path: string): Uint8Array

Derives a private key from a BIP-32 master node along the specified path.

Parameters:

Name	Type	Required	Description
masterNode	BIP32Interface	Yes	Master BIP-32 node.
path	string	Yes	BIP-32 derivation path.

Returns: Uint8Array — private key (32 bytes).

Throws: Error("No private key at derived node") — if the derived node does not contain a private key.

mnemonicToSeed

mnemonicToSeed(mnemonicWords: string[] | string, passphrase?: string): Promise<Uint8Array>

Converts a mnemonic to a 64-byte BIP-39 seed using PBKDF2-HMAC-SHA512.

Parameters:

Name	Type	Required	Description
mnemonicWords	string[] | string	Yes	Mnemonic as array or space-separated string.
passphrase	string	No	Optional BIP-39 passphrase. Defaults to "".

Returns: Promise<Uint8Array> — seed bytes (64 bytes).

seedToMasterNode

seedToMasterNode(seed: Uint8Array): BIP32Interface

Creates a BIP-32 master node from a seed using tiny-secp256k1 and the bip32 factory.

Parameters:

Name	Type	Required	Description
seed	Uint8Array	Yes	Seed bytes (typically 64 bytes from mnemonicToSeed).

Returns: BIP32Interface — master node for key derivation.

deriveKeyFromMnemonic

deriveKeyFromMnemonic(mnemonicWords: string[], options?: Bip44PathOptions): Promise<Uint8Array>

Full derivation pipeline: mnemonic → seed → master node → private key.

Parameters:

Name	Type	Required	Description
mnemonicWords	string[]	Yes	Mnemonic word array.
options	Bip44PathOptions	No	BIP-44 path options. Uses defaults if omitted.

Returns: Promise<Uint8Array> — derived private key (32 bytes).

deriveNextKeyFromMnemonic

deriveNextKeyFromMnemonic(
  mnemonicWords: string[],
  currentIndex: number,
  options?: Omit<Bip44PathOptions, 'index'>
): Promise<Uint8Array>

Derives the key at currentIndex + 1 from the mnemonic.

Parameters:

Name	Type	Required	Description
mnemonicWords	string[]	Yes	Mnemonic word array.
currentIndex	number	Yes	Current derivation index. The next key is derived at currentIndex + 1.
options	Omit<Bip44PathOptions, 'index'>	No	BIP-44 path options (without index).

Returns: Promise<Uint8Array> — private key at the next index.