zero dependency ksuid implementation

ksuid-browser-only.js

// KSUIDs should be 20 bytes: 4 for the timestamp and 16 for the payload
const TIMESTAMP_BYTES = 4;
const PAYLOAD_BYTES = 16;
const TOTAL_BYTES = TIMESTAMP_BYTES + PAYLOAD_BYTES;

function getCurrentTimestamp() {
  // KSUID timestamps have a custom epoch that starts in 14e8
  const CUSTOM_EPOCH_DIFF = 1_400_000_000;

  const timestamp = Math.floor(Date.now() / 1000) - CUSTOM_EPOCH_DIFF;
  const timestampArray = new Uint8Array(TIMESTAMP_BYTES);

  // Write the timestamp to the buffer in Big Endian format
  new DataView(timestampArray.buffer).setUint32(0, timestamp);
  
  return timestampArray;
}

function generatePayload() {
  const payloadArray = new Uint8Array(PAYLOAD_BYTES);
  window.crypto.getRandomValues(payloadArray);
  return payloadArray;
}

function toBase62(uint8Array) {
  const characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
  let result = '';

  let quotient = BigInt(`0x${Array.from(uint8Array).map(b => b.toString(16).padStart(2, '0')).join('')}`);
  while (quotient > 0) {
    const remainder = Number(quotient % 62n);
    quotient /= 62n;

    result = characters[remainder] + result;
  }

  return result.padStart(26, '0');
}

function generateKSUID() {
  const ksuidArray = new Uint8Array(TOTAL_BYTES);
  
  ksuidArray.set(getCurrentTimestamp(), 0);
  ksuidArray.set(generatePayload(), TIMESTAMP_BYTES);

  // Convert to a base62 string for easier handling
  return toBase62(ksuidArray);
}

ksuid-isomorphic.js

// KSUIDs should be 20 bytes: 4 for the timestamp and 16 for the payload
const TIMESTAMP_BYTES = 4;
const PAYLOAD_BYTES = 16;
const TOTAL_BYTES = TIMESTAMP_BYTES + PAYLOAD_BYTES;

function isBrowserEnvironment() {
    return typeof window !== 'undefined';
}

function getCurrentTimestamp() {
    // KSUID timestamps have a custom epoch that starts in 14e8
    const CUSTOM_EPOCH_DIFF = 1_400_000_000;

    const timestamp = Math.floor(Date.now() / 1000) - CUSTOM_EPOCH_DIFF;
    if (isBrowserEnvironment()) {
        const timestampArray = new Uint8Array(TIMESTAMP_BYTES);
        new DataView(timestampArray.buffer).setUint32(0, timestamp);
        return timestampArray;
    } else {
        const timestampBuffer = Buffer.alloc(TIMESTAMP_BYTES);
        timestampBuffer.writeUInt32BE(timestamp, 0);
        return timestampBuffer;
    }
}

function generatePayload() {
    if (isBrowserEnvironment()) {
        const payloadArray = new Uint8Array(PAYLOAD_BYTES);
        window.crypto.getRandomValues(payloadArray);
        return payloadArray;
    } else {
        return require('crypto').randomBytes(PAYLOAD_BYTES);
    }
}

function toBase62(uint8Array) {
    const characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    let result = '';

    let quotient = BigInt(`0x${Array.from(uint8Array).map(b => b.toString(16).padStart(2, '0')).join('')}`);
    while (quotient > 0) {
        const remainder = Number(quotient % 62n);
        quotient /= 62n;

        result = characters[remainder] + result;
    }

    return result.padStart(26, '0');
}

function generateKSUID() {
    const ksuidArray = new (isBrowserEnvironment() ? Uint8Array : Buffer)(TOTAL_BYTES);
  
    ksuidArray.set(getCurrentTimestamp(), 0);
    ksuidArray.set(generatePayload(), TIMESTAMP_BYTES);

    // Convert to a base62 string for easier handling
    return toBase62(ksuidArray);
}

ksuid-node-only.js

const crypto = require('crypto');

// KSUIDs should be 20 bytes: 4 for the timestamp and 16 for the payload
const TIMESTAMP_BYTES = 4;
const PAYLOAD_BYTES = 16;
const TOTAL_BYTES = TIMESTAMP_BYTES + PAYLOAD_BYTES;

function getCurrentTimestamp() {
  // KSUID timestamps have a custom epoch that starts in 14e8
  const CUSTOM_EPOCH_DIFF = 1_400_000_000;

  const timestamp = Math.floor(Date.now() / 1000) - CUSTOM_EPOCH_DIFF;
  const timestampBuffer = Buffer.alloc(TIMESTAMP_BYTES);
  
  // Write the timestamp to the buffer in Big Endian format
  timestampBuffer.writeUInt32BE(timestamp, 0);
  
  return timestampBuffer;
}

function generatePayload() {
  return crypto.randomBytes(PAYLOAD_BYTES);
}

function toBase62(buffer) {
  const characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
  let result = '';

  let quotient = BigInt(`0x${buffer.toString('hex')}`);
  while (quotient > 0) {
    const remainder = Number(quotient % 62n);
    quotient /= 62n;

    result = characters[remainder] + result;
  }

  return result;
}

function generateKSUID() {
  const ksuidBuffer = Buffer.alloc(TOTAL_BYTES);
  
  getCurrentTimestamp().copy(ksuidBuffer, 0, 0, TIMESTAMP_BYTES);
  generatePayload().copy(ksuidBuffer, TIMESTAMP_BYTES, 0, PAYLOAD_BYTES);

  // Convert to a base62 string for easier handling
  return toBase62(ksuidBuffer);
}