When I write data to a BLE Characteristic (FFE1) to send data over bluetooth, is the data encrypted?
I found one sentence as part of another answer that seems to indicate that writing data to a characteristic before being bonded means that the data is not encrypted.


  "You will not have encrypted characteristic read/write without
  bonding."*



from this answer on stackoverflow https://stackoverflow.com/questions/17963954/bluetooth-low-energy-encryption-and-data-safety


That wasn't quite definitive however.

Then I finally found the following (at https://www.silabs.com/community/wireless/bluetooth/knowledge-base.entry.html/2015/08/06/_reference_bonding-lnVL) : 


  In classic Bluetooth (v2.0, v2.1, v3.0), you have to pair with a
  device before you can connect with it, and then you have to connect
  with it before you can communicate with it. During pairing, link
  security keys are generated and stored on each module so that they can
  communicate with each other again in the future if desired without
  needing to pair again.
  
  With Bluetooth Smart [aka BLE], however, it quite common to connect and
  communicate without pairing. You can even send a small amount of user
  definable data to any listening devices without any connection at all
  via advertisement packets, somewhat like a super-charged custom
  INQUIRY response. However, if you connect without pairing, then the
  connection is not secure, because there are no link security keys that
  may be used to encrypt the connection.


That's very good info since it compares everything to Bluetooth 2, 2.1., 3 since I know they do force you to pair and then all data transmitted is encrypted and I was wondering about the comparison to BLE.

I also found documentation for the cc2541 via TI(Texas Instruments) which contains the following table and steps for insuring security (my highlights):


This all seems to support the fact that data is only encrypted after pairing.

In my case / question I was asking if the data is encrypted even though I am not pairing so I believe this helps create a definitive answer that the data I'm sending that way is not encrypted via BLE.

Also the additional steps that define the "general process to establish security" lead me to the same conclusion -- that encryption is only done when devices are paired.