What is Synology Cloud Sync Decryption Tool?

Cloud Sync Decryption Tool is a program to decrypt data encrypted by Cloud Sync, designed for function evaluation and data recovery in case of emergency. When an incident renders your Synology NAS inaccessible, you can download the encrypted files uploaded by Cloud Sync from the public clouds, and use Cloud Sync Decryption Tool to decrypt them.

Please note that you can always restore encrypted data simply by creating a new task in Cloud Sync with the exact account information and password used in the previous encryption task. If you lose your password but still have the key file exported from Cloud Sync, you can leverage the tool to recover encrypted data.

To decrypt data

  1. Click SynologyCloudSyncDecryptionTool to launch the program.
  2. Choose the method to decrypt data. You can either input password or provide a private key file.
  3. Select the encrypted data, which could be either a folder or a file.
  4. Select the output folder.
  5. Click Decrypt to start the decryption process.
  6. Progress will be shown after the decryption process has begun. Click Cancel to cancel the decryption process.


  • Cloud Sync Decryption Tool supports two decryption methods:
    • Password: the input password must be identical with the password used in the setup of Cloud Sync encryption task.
    • Private key: Cloud Sync will automatically export your keys when linked to a public cloud for the first time. You can find the private key file (private.pem) in the exported key file.
  • Cloud Sync Decryption Tool is able to decrypt a single file or an entire folder. If you choose to decrypt a folder, all files in the folder will be decrypted and saved to the output folder in relative paths.