code: def getSignatureKey(key, dateStamp, regionName, serviceName):
      
      kDate = sign((b'AWS4' + key), dateStamp)
      kRegion = sign(kDate, regionName)
      kService = sign(kRegion, serviceName)
      kSigning = sign(kService, b'aws4_request')
      return kSigning
docs: Generate the signing key for AWS V4 requests.
  
      @param key: The secret key to use.
      @type key: L{bytes}
  
      @param dateStamp: The UTC date and time, serialized as an AWS date
          stamp.
      @type dateStamp: L{bytes}
  
      @param regionName: The name of the region.
      @type regionName: L{bytes}
  
      @param serviceName: The name of the service to which the request
          will be sent.
      @type serviceName: L{bytes}
  
      @return: The signature.
      @rtype: L{bytes}