code: function SHA256() {
    if (!(this instanceof SHA256))
      return new SHA256();
  
    this.s = new Array(8);
    this.w = new Array(64);
    this.block = Buffer.allocUnsafe(64);
    this.bytes = 0;
  }
docs: SHA256
  @alias module:crypto/sha256.SHA256
  @constructor
  @property {Number[]} s
  @property {Number[]} w
  @property {Buffer} block
  @property {Number} bytes