Shade/packages/shade-key-transparency/src/util.ts

/**
 * Constant-time byte comparison. Mirrors `@shade/core` `constantTimeEqual`
 * but is duplicated here so the KT package has no runtime dependency on
 * `@shade/core` for primitive comparisons (it depends on it for error
 * types only).
 */
export function constantTimeEqual(a: Uint8Array, b: Uint8Array): boolean {
  if (a.length !== b.length) return false;
  let diff = 0;
  for (let i = 0; i < a.length; i++) {
    diff |= a[i]! ^ b[i]!;
  }
  return diff === 0;
}

/**
 * Encode bytes to standard base64 (no URL variant). Avoids platform-specific
 * `Buffer` so the KT package works in browsers, Bun, and Workers.
 */
export function toBase64(bytes: Uint8Array): string {
  if (typeof Buffer !== 'undefined') return Buffer.from(bytes).toString('base64');
  let str = '';
  for (let i = 0; i < bytes.length; i++) str += String.fromCharCode(bytes[i]!);
  return btoa(str);
}

export function fromBase64(s: string): Uint8Array {
  if (typeof Buffer !== 'undefined') return new Uint8Array(Buffer.from(s, 'base64'));
  const str = atob(s);
  const out = new Uint8Array(str.length);
  for (let i = 0; i < str.length; i++) out[i] = str.charCodeAt(i);
  return out;
}

/** Stable hex encoding for log_id rendering. */
export function toHex(bytes: Uint8Array): string {
  let s = '';
  for (let i = 0; i < bytes.length; i++) {
    s += bytes[i]!.toString(16).padStart(2, '0');
  }
  return s;
}