aes-cmac/lib/aes-cmac.cjs

AES-CMAC implementation in typescript

'use strict';

class BufferTools {
  static bitShiftLeft(input) {
    const output = new Uint8Array(input.length);
    let overflow = 0;
    for (let i = input.length - 1; i >= 0; i--) {
      const byte = input[i];
      output[i] = byte << 1 | overflow;
      overflow = byte & 128 ? 1 : 0;
    }
    return output;
  }
  static xor(a, b) {
    const length = Math.min(a.length, b.length);
    const output = new Uint8Array(length);
    for (let i = 0; i < length; i++) {
      output[i] = a[i] ^ b[i];
    }
    return output;
  }
  static toBinaryString(input) {
    let binary = "";
    for (let i = 0; i < input.length; i++) {
      for (let b = 7; b >= 0; b--) {
        const byte = input[i];
        binary += byte & 1 << b ? "1" : "0";
      }
    }
    return binary;
  }
}

var __defProp = Object.defineProperty;
var __defNormalProp = (obj, key, value) => key in obj ? __defProp(obj, key, { enumerable: true, configurable: true, writable: true, value }) : obj[key] = value;
var __publicField = (obj, key, value) => __defNormalProp(obj, typeof key !== "symbol" ? key + "" : key, value);
class AesCmac {
  constructor(key) {
    __publicField(this, "blockSize", 16);
    __publicField(this, "supportedLengths", [16, 24, 32]);
    __publicField(this, "subkeys");
    __publicField(this, "key");
    if (key instanceof Uint8Array === false) {
      throw new Error("The key must be provided as a Uint8Array.");
    }
    if (this.supportedLengths.includes(key.length) === false) {
      throw new Error("Key size must be 128, 192, or 256 bits.");
    }
    this.key = crypto.subtle.importKey("raw", key, "AES-CBC", false, ["encrypt"]);
  }
  async generateSubkeys() {
    const rb = Uint8Array.from([
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      0,
      135
    ]);
    const z = new Uint8Array(this.blockSize);
    const l = await this.aes(z);
    let key1 = BufferTools.bitShiftLeft(l);
    if (l[0] & 128) {
      key1 = BufferTools.xor(key1, rb);
    }
    let key2 = BufferTools.bitShiftLeft(key1);
    if (key1[0] & 128) {
      key2 = BufferTools.xor(key2, rb);
    }
    return { key1, key2 };
  }
  async getSubKeys() {
    if (!this.subkeys) {
      this.subkeys = await this.generateSubkeys();
    }
    const key1 = new Uint8Array(this.blockSize);
    key1.set(this.subkeys.key1);
    const key2 = new Uint8Array(this.blockSize);
    key2.set(this.subkeys.key2);
    return { key1, key2 };
  }
  async calculate(message) {
    if (message instanceof Uint8Array === false) {
      throw new Error("The message must be provided as a Uint8Array.");
    }
    const blockCount = this.getBlockCount(message);
    let x = new Uint8Array(this.blockSize);
    let y = new Uint8Array(0);
    for (let i = 0; i < blockCount - 1; i++) {
      const from = i * this.blockSize;
      const block = message.slice(from, from + this.blockSize);
      y = BufferTools.xor(x, block);
      x = await this.aes(y);
    }
    y = BufferTools.xor(x, await this.getLastBlock(message));
    x = await this.aes(y);
    return x;
  }
  getBlockCount(message) {
    const blockCount = Math.ceil(message.length / this.blockSize);
    return blockCount === 0 ? 1 : blockCount;
  }
  async aes(message) {
    const iv = new Uint8Array(this.blockSize);
    if ("then" in this.key) {
      this.key = await this.key;
    }
    const aesCiphertext = await crypto.subtle.encrypt(
      { name: "AES-CBC", iv },
      this.key,
      message
    );
    return new Uint8Array(aesCiphertext.slice(0, 16));
  }
  async getLastBlock(message) {
    if (!this.subkeys) {
      this.subkeys = await this.generateSubkeys();
    }
    const blockCount = this.getBlockCount(message);
    const paddedBlock = this.padding(message, blockCount - 1);
    let complete = false;
    if (message.length > 0) {
      complete = message.length % this.blockSize === 0;
    }
    const key = complete ? this.subkeys.key1 : this.subkeys.key2;
    return BufferTools.xor(paddedBlock, key);
  }
  padding(message, blockIndex) {
    const block = new Uint8Array(this.blockSize);
    const from = blockIndex * this.blockSize;
    const slice = message.slice(from, from + this.blockSize);
    block.set(slice);
    if (slice.length !== this.blockSize) {
      block[slice.length] = 128;
    }
    return block;
  }
}

exports.AesCmac = AesCmac;
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