text: 
  
  /**
   * find the multiplicative inverse of i in GF(2^8)
   *
   * denote i'(x) = i^-1(x), the multiplicative inverse of i
   * i(x) * i'(x) = 1 (mod m(x))
   *
   * for AES the module is 0x11b, (x^8 + x^4 + x^3 + x + 1)
   *
   * for the special value 0, the inverse is set to 0
   * for other cases, here finds them by trails
   * @param {Number} i
   */
  const inv = (() => {
    const mem = [0, 1];
    const m = 0x11b;
    return (i) => {
      if (mem[i] !== undefined) return mem[i];
  
      // i(x) * x^0 mod m(x)
      const i01 = i;
      // i(x) * x^1 mod m(x)
      const i02 = i01 & 0x80 ? (i01 << 1) ^ m : i01 << 1;
      // i(x) * x^2 mod m(x)
      const i04 = i02 & 0x80 ? (i02 << 1) ^ m : i02 << 1;
      // i(x) * x^3 mod m(x)
      const i08 = i04 & 0x80 ? (i04 << 1) ^ m : i04 << 1;
      // i(x) * x^4 mod m(x)
      const i10 = i08 & 0x80 ? (i08 << 1) ^ m : i08 << 1;
      // i(x) * x^5 mod m(x)
      const i20 = i10 & 0x80 ? (i10 << 1) ^ m : i10 << 1;
      // i(x) * x^6 mod m(x)
      const i40 = i20 & 0x80 ? (i20 << 1) ^ m : i20 << 1;
      // i(x) * x^7 mod m(x)
      const i80 = i40 & 0x80 ? (i40 << 1) ^ m : i40 << 1;
  
      for (let t = 2; t <= 0xff; t += 1) {
        if (mem[t] === undefined) {
          const it =
            (t & 0x01 ? i01 : 0) ^
            (t & 0x02 ? i02 : 0) ^
            (t & 0x04 ? i04 : 0) ^
            (t & 0x08 ? i08 : 0) ^
            (t & 0x10 ? i10 : 0) ^
            (t & 0x20 ? i20 : 0) ^
            (t & 0x40 ? i40 : 0) ^
            (t & 0x80 ? i80 : 0);
          if (it === 0x01) {
            mem[i] = t;
            mem[t] = i;
            break;
          }
        }
      }
      return mem[i];
    };
  })();
  
  
  /**
   * affine transform of b in GF(2)
   *
   * b_i = b_i             <+>
   *       b_((i + 4) % 8) <+>
   *       b_((i + 5) % 8) <+>
   *       b_((i + 6) % 8) <+>
   *       b_((i + 7) % 8) <+>
   *       c_i;
   *
   * where c = 0x63 (01100011)
   *
   * here implement bit transform as byte operation
   * @param {Number} b
   */
  const affineTrans = (b) => {
    const b4 = (b >>> 4) | (b << (8 - 4));
    const b5 = (b >>> 5) | (b << (8 - 5));
    const b6 = (b >>> 6) | (b << (8 - 6));
    const b7 = (b >>> 7) | (b << (8 - 7));
    const c = 0x63;
  
    return b ^ b4 ^ b5 ^ b6 ^ b7 ^ c;
  };
  
  
  export const constructSBox = () =>
    new Uint8Array(256).map((_, i) => affineTrans(inv(i)));
  
  // Here use a prepared table as S-Box, which is the result of the
  // constructSBox function
  export const S_BOX = Uint8Array.of(
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
  );
  
  export const INV_S_BOX = Uint8Array.of(
    0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
    0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
    0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
    0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
    0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
    0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
    0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
    0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
    0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
    0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
    0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
    0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
    0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
    0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
    0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d,
  );
  
  /**
   *
   * @param {{u8: Uint8Array}} state
   */
  export const subBytes = (state) => {
    const st = state.u8;
    st.forEach((v, i) => {
      st[i] = S_BOX[v];
    });
    return state;
  };
  /**
   *
   * @param {{u8: Uint8Array}} state
   */
  export const invSubBytes = (state) => {
    const st = state.u8;
    st.forEach((v, i) => {
      st[i] = INV_S_BOX[v];
    });
    return state;
  };
  
  export default { subBytes, invSubBytes };
  