zhywpt-h5/utils/util/sm4.js

/**
 * base64js
 * base64js.toByteArray(d.input)
 * base64js.fromByteArray(c);
 * 国密SM4加密算法
 * @email 1216113487@qq.com
 * 原作者：中科软wzk
 * 修改：徐一杰
 * 2021/12/24
 *
 * 调用方法：
 * import {SM4Util} from '@/utils/sm4';
 * var sm4 = new SM4Util();
 sm4.encryptData_CBC('');
 */
;(function (r) {
  if (typeof exports === 'object' && typeof module !== 'undefined') {
    module.exports = r()
  } else {
    let define
    if (typeof define === 'function' && define.amd) {
      define([], r)
    } else {
      var e
      if (typeof window !== 'undefined') {
        e = window
      } else {
        if (typeof global !== 'undefined') {
          e = global
        } else {
          if (typeof self !== 'undefined') {
            e = self
          } else {
            e = this
          }
        }
      }
      e.base64js = r()
    }
  }
})(function () {
  return (function r(e, t, n) {
    const f = typeof require == 'function' && require

    function o(i, a) {
      if (!t[i]) {
        if (!e[i]) {
          const u = typeof require == 'function' && require
          if (!a && u) {
            return u(i, !0)
          }
          if (f) {
            return f(i, !0)
          }
          const d = new Error("Cannot find module '" + i + "'")
          throw ((d.code = 'MODULE_NOT_FOUND'), d)
        }
        const c = (t[i] = { exports: {} })
        e[i][0].call(
          c.exports,
          function (r) {
            const t = e[i][1][r]
            return o(t ? t : r)
          },
          c,
          c.exports,
          r,
          e,
          t,
          n
        )
      }
      return t[i].exports
    }
    for (let i = 0; i < n.length; i++) {
      o(n[i])
    }
    return o
  })(
    {
      '/': [
        function (r, e, t) {
          t.byteLength = c
          t.toByteArray = v
          t.fromByteArray = s
          var n = []
          var o = []
          var f = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
          const i =
            'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
          let a = 0,
            u = i.length
          for (; a < u; ++a) {
            n[a] = i[a]
            o[i.charCodeAt(a)] = a
          }
          o['-'.charCodeAt(0)] = 62
          o['_'.charCodeAt(0)] = 63
          function d(r) {
            const e = r.length
            if (e % 4 > 0) {
              throw new Error('Invalid string. Length must be a multiple of 4')
            }
            return r[e - 2] === '=' ? 2 : r[e - 1] === '=' ? 1 : 0
          }
          function c(r) {
            return (r.length * 3) / 4 - d(r)
          }
          function v(r) {
            let e, t, n, i, a
            const u = r.length
            i = d(r)
            a = new f((u * 3) / 4 - i)
            t = i > 0 ? u - 4 : u
            let c = 0
            for (e = 0; e < t; e += 4) {
              n =
                (o[r.charCodeAt(e)] << 18) |
                (o[r.charCodeAt(e + 1)] << 12) |
                (o[r.charCodeAt(e + 2)] << 6) |
                o[r.charCodeAt(e + 3)]
              a[c++] = (n >> 16) & 255
              a[c++] = (n >> 8) & 255
              a[c++] = n & 255
            }
            if (i === 2) {
              n = (o[r.charCodeAt(e)] << 2) | (o[r.charCodeAt(e + 1)] >> 4)
              a[c++] = n & 255
            } else {
              if (i === 1) {
                n =
                  (o[r.charCodeAt(e)] << 10) |
                  (o[r.charCodeAt(e + 1)] << 4) |
                  (o[r.charCodeAt(e + 2)] >> 2)
                a[c++] = (n >> 8) & 255
                a[c++] = n & 255
              }
            }
            return a
          }
          function l(r) {
            return (
              n[(r >> 18) & 63] +
              n[(r >> 12) & 63] +
              n[(r >> 6) & 63] +
              n[r & 63]
            )
          }
          function h(r, e, t) {
            let n
            const o = []
            for (let f = e; f < t; f += 3) {
              n = (r[f] << 16) + (r[f + 1] << 8) + r[f + 2]
              o.push(l(n))
            }
            return o.join('')
          }
          function s(r) {
            let e
            const t = r.length
            const o = t % 3
            let f = ''
            const i = []
            const a = 16383
            let u = 0,
              d = t - o
            for (; u < d; u += a) {
              i.push(h(r, u, u + a > d ? d : u + a))
            }
            if (o === 1) {
              e = r[t - 1]
              f += n[e >> 2]
              f += n[(e << 4) & 63]
              f += '=='
            } else {
              if (o === 2) {
                e = (r[t - 2] << 8) + r[t - 1]
                f += n[e >> 10]
                f += n[(e >> 4) & 63]
                f += n[(e << 2) & 63]
                f += '='
              }
            }
            i.push(f)
            return i.join('')
          }
        },
        {},
      ],
    },
    {},
    []
  )('/')
})

/**
 * 国密SM4加密算法
 * @author wzk
 * @email 1216113487@qq.com
 * @company 中科软
 */
function SM4_Context() {
  this.mode = 1
  this.isPadding = true
  this.sk = new Array(32)
}

function SM4() {
  this.SM4_ENCRYPT = 1
  this.SM4_DECRYPT = 0

  const SboxTable = [
    0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2,
    0x28, 0xfb, 0x2c, 0x05, 0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3,
    0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99, 0x9c, 0x42, 0x50, 0xf4,
    0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
    0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa,
    0x75, 0x8f, 0x3f, 0xa6, 0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba,
    0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8, 0x68, 0x6b, 0x81, 0xb2,
    0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
    0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b,
    0x01, 0x21, 0x78, 0x87, 0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52,
    0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e, 0xea, 0xbf, 0x8a, 0xd2,
    0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
    0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30,
    0xf5, 0x8c, 0xb1, 0xe3, 0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60,
    0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f, 0xd5, 0xdb, 0x37, 0x45,
    0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
    0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41,
    0x1f, 0x10, 0x5a, 0xd8, 0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd,
    0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0, 0x89, 0x69, 0x97, 0x4a,
    0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
    0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e,
    0xd7, 0xcb, 0x39, 0x48,
  ]

  const FK = [0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc]

  const CK = [
    0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269, 0x70777e85, 0x8c939aa1,
    0xa8afb6bd, 0xc4cbd2d9, 0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
    0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9, 0xc0c7ced5, 0xdce3eaf1,
    0xf8ff060d, 0x141b2229, 0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
    0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209, 0x10171e25, 0x2c333a41,
    0x484f565d, 0x646b7279,
  ]

  this.GET_ULONG_BE = function (b, i) {
    return (
      ((b[i] & 0xff) << 24) |
      ((b[i + 1] & 0xff) << 16) |
      ((b[i + 2] & 0xff) << 8) |
      (b[i + 3] & 0xff & 0xffffffff)
    )
  }

  this.PUT_ULONG_BE = function (n, b, i) {
    var t1 = 0xff & (n >> 24)
    var t2 = 0xff & (n >> 16)
    var t3 = 0xff & (n >> 8)
    var t4 = 0xff & n
    b[i] = t1 > 128 ? t1 - 256 : t1
    b[i + 1] = t2 > 128 ? t2 - 256 : t2
    b[i + 2] = t3 > 128 ? t3 - 256 : t3
    b[i + 3] = t4 > 128 ? t4 - 256 : t4
  }

  this.SHL = function (x, n) {
    return (x & 0xffffffff) << n
  }

  this.ROTL = function (x, n) {
    // const s = this.SHL(x, n);
    // const ss = x >> (32 - n);
    return this.SHL(x, n) | (x >> (32 - n))
  }

  this.sm4Lt = function (ka) {
    let bb = 0
    let c = 0
    const a = new Array(4)
    const b = new Array(4)
    this.PUT_ULONG_BE(ka, a, 0)
    b[0] = this.sm4Sbox(a[0])
    b[1] = this.sm4Sbox(a[1])
    b[2] = this.sm4Sbox(a[2])
    b[3] = this.sm4Sbox(a[3])
    bb = this.GET_ULONG_BE(b, 0)
    c =
      bb ^
      this.ROTL(bb, 2) ^
      this.ROTL(bb, 10) ^
      this.ROTL(bb, 18) ^
      this.ROTL(bb, 24)
    return c
  }

  this.sm4F = function (x0, x1, x2, x3, rk) {
    return x0 ^ this.sm4Lt(x1 ^ x2 ^ x3 ^ rk)
  }

  this.sm4CalciRK = function (ka) {
    let bb = 0
    let rk = 0
    const a = new Array(4)
    const b = new Array(4)
    this.PUT_ULONG_BE(ka, a, 0)
    b[0] = this.sm4Sbox(a[0])
    b[1] = this.sm4Sbox(a[1])
    b[2] = this.sm4Sbox(a[2])
    b[3] = this.sm4Sbox(a[3])
    bb = this.GET_ULONG_BE(b, 0)
    rk = bb ^ this.ROTL(bb, 13) ^ this.ROTL(bb, 23)
    return rk
  }

  this.sm4Sbox = function (inch) {
    const i = inch & 0xff
    const retVal = SboxTable[i]
    return retVal > 128 ? retVal - 256 : retVal
  }

  this.sm4_setkey_enc = function (ctx, key) {
    if (ctx == null) {
      alert('ctx is null!')
      return false
    }
    if (key == null || key.length !== 16) {
      alert('key error!')
      return false
    }
    ctx.mode = this.SM4_ENCRYPT
    this.sm4_setkey(ctx.sk, key)
  }

  //生成解密密钥
  this.sm4_setkey_dec = function (ctx, key) {
    if (ctx == null) {
      Error('ctx is null!')
    }

    if (key == null || key.length !== 16) {
      Error('2key error!')
    }

    // var i = 0;
    ctx.mode = 0
    this.sm4_setkey(ctx.sk, key)
    ctx.sk = ctx.sk.reverse()
  }

  this.sm4_setkey = function (SK, key) {
    const MK = new Array(4)
    const k = new Array(36)
    // var i = 0;
    MK[0] = this.GET_ULONG_BE(key, 0)
    MK[1] = this.GET_ULONG_BE(key, 4)
    MK[2] = this.GET_ULONG_BE(key, 8)
    MK[3] = this.GET_ULONG_BE(key, 12)
    k[0] = MK[0] ^ FK[0]
    k[1] = MK[1] ^ FK[1]
    k[2] = MK[2] ^ FK[2]
    k[3] = MK[3] ^ FK[3]
    for (let i = 0; i < 32; i++) {
      k[i + 4] = k[i] ^ this.sm4CalciRK(k[i + 1] ^ k[i + 2] ^ k[i + 3] ^ CK[i])
      SK[i] = k[i + 4]
    }
  }
  this.padding = function (input, mode) {
    let p
    if (input == null) {
      return null
    }
    let ret = null
    if (mode === this.SM4_ENCRYPT) {
      p = parseInt(16 - (input.length % 16))
      ret = input.slice(0)
      for (let i = 0; i < p; i++) {
        ret[input.length + i] = p
      }
    } else {
      p = input[input.length - 1]
      ret = input.slice(0, input.length - p)
    }
    return ret
  }
  this.sm4_one_round = function (sk, input, output) {
    let i = 0
    const ulbuf = new Array(36)
    ulbuf[0] = this.GET_ULONG_BE(input, 0)
    ulbuf[1] = this.GET_ULONG_BE(input, 4)
    ulbuf[2] = this.GET_ULONG_BE(input, 8)
    ulbuf[3] = this.GET_ULONG_BE(input, 12)
    while (i < 32) {
      ulbuf[i + 4] = this.sm4F(
        ulbuf[i],
        ulbuf[i + 1],
        ulbuf[i + 2],
        ulbuf[i + 3],
        sk[i]
      )
      i++
    }
    this.PUT_ULONG_BE(ulbuf[35], output, 0)
    this.PUT_ULONG_BE(ulbuf[34], output, 4)
    this.PUT_ULONG_BE(ulbuf[33], output, 8)
    this.PUT_ULONG_BE(ulbuf[32], output, 12)
  }

  this.sm4_crypt_ecb = function (ctx, input) {
    if (input == null) {
      alert('input is null!')
    }
    if (ctx.isPadding && ctx.mode == this.SM4_ENCRYPT) {
      input = this.padding(input, this.SM4_ENCRYPT)
    }

    let i = 0
    let length = input.length
    let bous = []
    for (; length > 0; length -= 16) {
      var out = new Array(16)
      var ins = input.slice(i * 16, 16 * (i + 1))
      this.sm4_one_round(ctx.sk, ins, out)
      bous = bous.concat(out)
      i++
    }

    let output = bous
    if (ctx.isPadding && ctx.mode === this.SM4_DECRYPT) {
      output = this.padding(output, this.SM4_DECRYPT)
    }
    for (i = 0; i < output.length; i++) {
      if (output[i] < 0) {
        output[i] = output[i] + 256
      }
    }
    return output
  }

  this.sm4_crypt_cbc = function (ctx, iv, input) {
    let out
    let ins
    let out1
    let k
    if (iv == null || iv.length !== 16) {
      alert('iv error!')
    }

    if (input == null) {
      alert('input is null!')
    }

    if (ctx.isPadding && ctx.mode === this.SM4_ENCRYPT) {
      input = this.padding(input, this.SM4_ENCRYPT)
    }

    let i = 0
    let length = input.length
    let bous = []
    if (ctx.mode === this.SM4_ENCRYPT) {
      k = 0
      for (; length > 0; length -= 16) {
        out = new Array(16)
        out1 = new Array(16)
        ins = input.slice(k * 16, 16 * (k + 1))

        for (i = 0; i < 16; i++) {
          out[i] = ins[i] ^ iv[i]
        }
        this.sm4_one_round(ctx.sk, out, out1)
        iv = out1.slice(0, 16)
        bous = bous.concat(out1)
        k++
      }
    } else {
      let temp = []
      k = 0
      for (; length > 0; length -= 16) {
        out = new Array(16)
        out1 = new Array(16)
        ins = input.slice(k * 16, 16 * (k + 1))
        temp = ins.slice(0, 16)
        this.sm4_one_round(ctx.sk, ins, out)
        for (i = 0; i < 16; i++) {
          out1[i] = out[i] ^ iv[i]
        }
        iv = temp.slice(0, 16)
        bous = bous.concat(out1)
        k++
      }
    }

    let output = bous
    if (ctx.isPadding && ctx.mode === this.SM4_DECRYPT) {
      output = this.padding(output, this.SM4_DECRYPT)
    }

    for (i = 0; i < output.length; i++) {
      if (output[i] < 0) {
        output[i] = output[i] + 256
      }
    }
    return output
  }
}

export function SM4Util() {
  // 和后端key一致
  // 当时用CBC模式的时候
  this.iv = 'ZkR_SiNoSOFT=568'
  this.hexString = false

  // ECB模式加密
  this.encryptData_ECB = function (plainText) {
    try {
      const sm4 = new SM4()
      const ctx = new SM4_Context()
      ctx.isPadding = true
      ctx.mode = sm4.SM4_ENCRYPT
      const keyBytes = this.stringToByte(this.secretKey)
      sm4.sm4_setkey_enc(ctx, keyBytes)
      const encrypted = sm4.sm4_crypt_ecb(ctx, this.stringToByte(plainText))
      const cipherText = base64js.fromByteArray(encrypted)
      if (cipherText != null && cipherText.trim().length > 0) {
        cipherText.replace(/(\s*|\t|\r|\n)/g, '')
      }
      return cipherText
    } catch (e) {
      console.error(e)
      return null
    }
  }
  //解密_ECB
  this.decryptData_ECB = function (cipherText) {
    try {
      let sm4 = new SM4()
      let ctx = new SM4_Context()
      ctx.isPadding = true
      ctx.mode = sm4.SM4_ENCRYPT
      let keyBytes = this.stringToByte(this.secretKey)
      sm4.sm4_setkey_dec(ctx, keyBytes)
      let decrypted = sm4.sm4_crypt_ecb(ctx, base64js.toByteArray(cipherText))
      return utf8ByteToUnicodeStr(decrypted)
    } catch (e) {
      console.error(e)
      return null
    }
  }

  // CBC模式加密
  this.encryptData_CBC = function (plainText, secretKey) {
    try {
      plainText = JSON.stringify(plainText)
      const sm4 = new SM4()
      const ctx = new SM4_Context()
      ctx.isPadding = true
      ctx.mode = sm4.SM4_ENCRYPT

      const keyBytes = this.stringToByte(secretKey.substring(0, 16))
      const ivBytes = this.stringToByte(this.iv)

      sm4.sm4_setkey_enc(ctx, keyBytes)
      const encrypted = sm4.sm4_crypt_cbc(
        ctx,
        ivBytes,
        this.stringToByte(plainText)
      )
      const cipherText = base64js.fromByteArray(encrypted)
      if (cipherText != null && cipherText.trim().length > 0) {
        cipherText.replace(/(\s*|\t|\r|\n)/g, '')
      }
      return cipherText
    } catch (e) {
      console.error(e)
      return null
    }
  }
  //解密_CBC
  this.decryptData_CBC = function (cipherText, secretKey) {
    try {
      let sm4 = new SM4()
      let ctx = new SM4_Context()
      ctx.isPadding = true
      ctx.mode = sm4.SM4_ENCRYPT
      let keyBytes = this.stringToByte(secretKey.substring(0, 16))
      let ivBytes = this.stringToByte(this.iv)
      sm4.sm4_setkey_dec(ctx, keyBytes)
      let decrypted = sm4.sm4_crypt_cbc(
        ctx,
        ivBytes,
        base64js.toByteArray(cipherText.data.bizContent)
      )
      let bizContent = utf8ByteToUnicodeStr(decrypted)
      let begin = bizContent.indexOf('[')
      let end = bizContent.lastIndexOf(']')
      if (begin < 0 || begin > bizContent.indexOf('{')) {
        begin = bizContent.indexOf('{')
        end = bizContent.lastIndexOf('}')
      }
      cipherText.data.bizContent = bizContent.substring(begin, end + 1) || bizContent
      return cipherText
    } catch (e) {
      console.error(e)
      return null
    }
  }

  this.stringToByte = function (str) {
    const bytes = []
    let len, c
    len = str.length
    for (let i = 0; i < len; i++) {
      c = str.charCodeAt(i)
      if (c >= 0x010000 && c <= 0x10ffff) {
        bytes.push(((c >> 18) & 0x07) | 0xf0)
        bytes.push(((c >> 12) & 0x3f) | 0x80)
        bytes.push(((c >> 6) & 0x3f) | 0x80)
        bytes.push((c & 0x3f) | 0x80)
      } else if (c >= 0x000800 && c <= 0x00ffff) {
        bytes.push(((c >> 12) & 0x0f) | 0xe0)
        bytes.push(((c >> 6) & 0x3f) | 0x80)
        bytes.push((c & 0x3f) | 0x80)
      } else if (c >= 0x000080 && c <= 0x0007ff) {
        bytes.push(((c >> 6) & 0x1f) | 0xc0)
        bytes.push((c & 0x3f) | 0x80)
      } else {
        bytes.push(c & 0xff)
      }
    }
    return bytes
  }

  this.byteToString = function (arr) {
    if (typeof arr === 'string') {
      return arr
    }
    let str = '',
      _arr = arr
    for (let i = 0; i < _arr.length; i++) {
      const one = _arr[i].toString(2),
        v = one.match(/^1+?(?=0)/)
      if (v && one.length === 8) {
        const bytesLength = v[0].length
        let store = _arr[i].toString(2).slice(7 - bytesLength)
        for (let st = 1; st < bytesLength; st++) {
          store += _arr[st + i].toString(2).slice(2)
        }
        str += String.fromCharCode(parseInt(store, 2))
        i += bytesLength - 1
      } else {
        str += String.fromCharCode(_arr[i])
      }
    }
    return str
  }

  function utf8ByteToUnicodeStr(utf8Bytes) {
    var unicodeStr = ''
    for (var pos = 0; pos < utf8Bytes.length; ) {
      var flag = utf8Bytes[pos]
      var unicode = 0
      if (flag >>> 7 === 0) {
        unicodeStr += String.fromCharCode(utf8Bytes[pos])
        pos += 1
      } else if ((flag & 0xfc) === 0xfc) {
        unicode = (utf8Bytes[pos] & 0x3) << 30
        unicode |= (utf8Bytes[pos + 1] & 0x3f) << 24
        unicode |= (utf8Bytes[pos + 2] & 0x3f) << 18
        unicode |= (utf8Bytes[pos + 3] & 0x3f) << 12
        unicode |= (utf8Bytes[pos + 4] & 0x3f) << 6
        unicode |= utf8Bytes[pos + 5] & 0x3f
        unicodeStr += String.fromCharCode(unicode)
        pos += 6
      } else if ((flag & 0xf8) === 0xf8) {
        unicode = (utf8Bytes[pos] & 0x7) << 24
        unicode |= (utf8Bytes[pos + 1] & 0x3f) << 18
        unicode |= (utf8Bytes[pos + 2] & 0x3f) << 12
        unicode |= (utf8Bytes[pos + 3] & 0x3f) << 6
        unicode |= utf8Bytes[pos + 4] & 0x3f
        unicodeStr += String.fromCharCode(unicode)
        pos += 5
      } else if ((flag & 0xf0) === 0xf0) {
        unicode = (utf8Bytes[pos] & 0xf) << 18
        unicode |= (utf8Bytes[pos + 1] & 0x3f) << 12
        unicode |= (utf8Bytes[pos + 2] & 0x3f) << 6
        unicode |= utf8Bytes[pos + 3] & 0x3f
        unicodeStr += String.fromCharCode(unicode)
        pos += 4
      } else if ((flag & 0xe0) === 0xe0) {
        unicode = (utf8Bytes[pos] & 0x1f) << 12
        unicode |= (utf8Bytes[pos + 1] & 0x3f) << 6
        unicode |= utf8Bytes[pos + 2] & 0x3f
        unicodeStr += String.fromCharCode(unicode)
        pos += 3
      } else if ((flag & 0xc0) === 0xc0) {
        //110
        unicode = (utf8Bytes[pos] & 0x3f) << 6
        unicode |= utf8Bytes[pos + 1] & 0x3f
        unicodeStr += String.fromCharCode(unicode)
        pos += 2
      } else {
        unicodeStr += String.fromCharCode(utf8Bytes[pos])
        pos += 1
      }
    }
    return unicodeStr
  }
}