expo-crypto/src/aes/web-utils.ts

Provides cryptography primitives for Android, iOS and web.

import type { BinaryInput } from './aes.types';

export function hexToUintArray(hexString: string): Uint8Array {
  const byteLength = hexString.length / 2;
  const bytes = new Uint8Array(byteLength);
  for (let i = 0; i < hexString.length; i += 2) {
    bytes[i >>> 1] = parseInt(hexString.substring(i, i + 2), 16);
  }
  return bytes;
}

export function bytesToHex(bytes: Uint8Array): string {
  const hex = [];
  for (const byte of bytes) {
    const current = byte < 0 ? byte + 256 : byte;
    hex.push((current >>> 4).toString(16));
    hex.push((current & 0xf).toString(16));
  }
  return hex.join('');
}

export function base64ToUintArray(base64String: string): Uint8Array {
  const binaryString = atob(base64String);
  const len = binaryString.length;
  const bytes = new Uint8Array(len);
  for (let i = 0; i < len; i++) {
    bytes[i] = binaryString.charCodeAt(i);
  }
  return bytes;
}
export function uint8ArrayToBase64(uint8Array: Uint8Array) {
  let binaryString = '';
  for (const byte of uint8Array) {
    binaryString += String.fromCharCode(byte);
  }

  return btoa(binaryString);
}

export function binaryInputBytes(input: BinaryInput): Uint8Array {
  if (input instanceof Uint8Array) {
    return input;
  }

  if (input instanceof ArrayBuffer) {
    return new Uint8Array(input);
  }

  if (ArrayBuffer.isView(input)) {
    return new Uint8Array(input.buffer);
  }

  if (typeof input === 'string') {
    return base64ToUintArray(input);
  }

  throw new Error('Cannot parse serializable input as ArrayBuffer');
}