Encryption used by Dropbox?

Hi adoo, here are some of the facts as far as I know on the topic: 

1. On transit, your data is encrypted using 128-bit or higher Advanced Encryption Standard (AES) encryption and travels via TLS/SSL.
2. Your data is stored in the Dropbox servers as random data blocks and encrypted using 256 bit AES.
3. Note that the data is encrypted by Dropbox on your behalf and therefore not end-to-end encrypted.
4. Dropbox maybe forced to hand over your data to law enforcement/governments if provided with a court order.
5. If you are worried aobut No. 4 scenario, you must encrypt your data yourself prior to uploading to Dropbox server. For example, you may use a third party tool like Truecrypt, Veracrypt etc. But this comes as a price of convenience.
6. Your data are not encrypted localy on your device hard drive by Dropbox. You should protect the local data yourself. Most operating sysmtems give ways to do this, for example, in Windows you may turn on BitLocker; in MacOS you have File Vault. As far as your OS account is secured by password, and/or biometric, and/or 2FA, your local data is safe.

You may read more about Dropbox business security here https://www.dropbox.com/business/trust/security/architecture