code: function constantTimeCompare (val1, val2) {
    let sentinel
  
    if (val1.length !== val2.length) return false
  
    for (let i = 0, len = val1.length; i < len; i++) {
      sentinel |= val1.charCodeAt(i) ^ val2.charCodeAt(i)
    }
  
    return sentinel === 0
  }
docs: Ensures the encrypted payload has not been tampered with.
  @param {string} val1 - Hash to compare
  @param {string} val2 - Hash to compare to
  @return {boolean} Whether it is valid