@iacobus/hd
Version:
Hierarchical Deterministic Symmetric Keys.
88 lines (87 loc) • 3.28 kB
JavaScript
/**
* @fileoverview Exports utility functions.
* @author Jacob V. B. Haap <iacobus.xyz>
* @license MIT
*/
import { hmac } from "@noble/hashes/hmac";
/** calcSalt creates a 16 byte salt from a given hash, message, and optional context info. */
export function calcSalt(h, msg, info) {
if (info) {
const hash = h.create().update(info); // Hash to expand the info
info = hash.digest().slice(0, 16); // Expanded info from hash digest
}
else {
info = new Uint8Array(16); // 16 byte array
}
const mac = hmac.create(h, info); // Create HMAC using info
mac.update(msg);
const domain = Uint8Array.from([83, 65, 76, 84]); // Bytes SALT for domain separation
mac.update(domain);
return mac.digest().slice(0, 16); // Return a salt from the MAC digest
}
/** encodeInt encodes a given integer as a 4 byte Uint8Array. */
export function encodeInt(int) {
const buf = new Uint8Array(4);
buf[0] = (int >>> 24) & 0xff;
buf[1] = (int >>> 16) & 0xff;
buf[2] = (int >>> 8) & 0xff;
buf[3] = int & 0xff;
return buf;
}
/** strToIndex obtains a 32 bit integer from a given hash and string. */
export function strToIndex(h, str) {
const sum = h.create().update(str).digest().slice(0, 4); // Create a hash of the string
const buf = new DataView(new Uint8Array(sum).buffer); // Dataview of the hash digest
return buf.getUint32(0, false); // Return 32 bit integer from the buffer
}
/** getIndex obtains a 32 bit integer index from a given hash, index string, and type. */
export function getIndex(h, index, type) {
if (!["num", "str", "any"].includes(type)) {
throw new TypeError(`type "${type}" invalid for index`);
}
let i;
if (type === "num") {
try {
const n = parseInt(index, 10); // Parse string to integer
if (!Number.isInteger(n) || n < 0 || n > 0xFFFFFFFF) {
throw new RangeError(`parsed index outside of uint32 range`);
}
i = n;
}
catch (error) {
throw new TypeError(`invalid numeric index "${index}", ${error}`);
}
}
else if (type === "str") {
try {
i = strToIndex(h, index); // Convert string to an integer
}
catch (error) {
throw new TypeError(`invalid alphabetic index "${index}", ${error}`);
}
}
else {
try {
const n = parseInt(index, 10); // Try parsing integer first
if (!Number.isInteger(n) || n < 0 || n > 0xFFFFFFFF) {
throw new RangeError(`parsed index outside of uint32 range`);
}
i = n;
}
catch {
try {
i = strToIndex(h, index); // Try string conversion next
}
catch (error) {
throw new SyntaxError(`invalid index "${index}", ${error}`);
}
}
}
return i;
}
/** fingerprint calculates a fingerprint from a given hash, parent key, and child key. */
export function fingerprint(h, parent, child) {
const mac = hmac.create(h, parent); // Create an HMAC using the parent
mac.update(child); // Write the child to the MAC
return mac.digest().slice(0, 16); // Return the MAC as the fingerprint
}