This page describes how Transfer Appliance secures and encrypts your data.
Google's infrastructure data security
When you return an appliance, we receive it at one of our Google data centers. Securing customer data is our top priority and responsibility. For more information about our infrastructure security, see Google Infrastructure Security Design Overview, and for more information about our data center security practices, see Data and Security.
Securing the appliance in transit
When you receive your appliance, you run the Transfer Appliance Attestation Application. This application validates the appliance identity and its state, to ensure that the appliance is in the same state as it was when we shipped it to you. The application generates an attestation passcode that you share with us. If the attestation passcode matches what we expect, we provide the login credentials for the appliance.
When you're done using the appliance and we've received the appliance from you, we validate the appliance again to ensure that it wasn't tampered with during shipping. After we've verified the appliance, we upload your data to Cloud Storage.
If the appliance validation indicates that the appliance was tampered with at any point, we invalidate the entire transfer session and work with you to ship you a replacement appliance.
Your data is encrypted during upload, during transit to our data centers, and after it has been uploaded to Cloud Storage. The following are details of how we encrypt your data:
During transit to Cloud Storage: Your data is encrypted on Transfer Appliance with
dm-encryptand partition-level encryption, with the AES-256 encryption algorithm.
During upload to Cloud Storage: Your data is encrypted using secure TLS connections. We transfer the encrypted data on your appliance to Cloud Storage. For customers using VPC Service Controls, this process occurs within your VPC Service Controls perimeter.
On Cloud Storage Your data is encrypted on Cloud Storage by default. For more details, see Data encryption options.
Encrypting data in transit to your appliance
We do not apply encryption between your storage or network devices and your appliance. Securing the network and physical access to the appliance is your responsibility. We do not access or monitor the appliance while it is connected to your network.
Encrypting data on your appliance
We use two keys to encrypt data on your appliance:
- A key encryption key, which is applied to the data encryption key before you return the appliance to us.
- A data encryption key, which is applied to your data before it is written to the appliance's disks.
Key encryption key (KEK)
You have the following two choices for the KEK:
You can create a customer-managed key, where you generate and manage the key yourself.
You can select a Google-managed key, in which we generate and manage the key.
Google-managed keys are unique per session, and are not shared with other Google Cloud services. When a session is completed or cancelled, or if an appliance is lost, we destroy the key to ensure your data security.
The following are the settings used to create Google-managed keys:
- Region: /kms/docs/locations#global
- Protection level: Software
- Purpose: Asymmetric decrypt
- Algorithm: 4096-bit RSA - OAEP Padding - SHA256 Digest
Destroying the KEK before the session is completed results in complete data loss on the appliance.
The KEK is generated as a Cloud Key Management Service (Cloud KMS) asymmetric key in Google Cloud, and we download the KEK public key to the appliance before we ship it to you.
Data encryption key (DEK)
The DEK is generated on the appliance. The DEK is kept in memory, and is stored on the appliance's Trusted Platform Module to persist the key across reboots. The DEK is never stored on a local disk unencrypted.
The appliance applies the generated DEK to your data before writing your data to disk. When you finalize the data on the appliance, the KEK public key is applied to the DEK, and then the DEK is removed from the appliance.
Data is never stored unencrypted on the appliance.
Restricting access to data on your appliance
To restrict access to the data stored on your appliance's NFS shares, you can apply an IP filter that allows specific hosts on your network to access the appliance. Contact your network administrator for assistance.
For more information about the IP network ports that Transfer Appliance uses, see Configuring IP network ports.
Uploading data to Cloud Storage
When we receive your appliance in one of our secured data centers, we upload your encrypted data into your VPC Service Controls perimeter before applying the KEK to decrypt the DEK and your data. The DEK is never persisted at any point during the transfer lifecycle. Then we securely move your data to Cloud Storage on our private data center network using secure TLS connections. Your data is encrypted in Cloud Storage by default, and is accessible only to you.
Appliance media sanitization
After uploading your data, we sanitize the drive media in the appliance you returned by applying NIST 800-88 standards for purging information. Specifically, we use cryptographic erasure to sanitize all encrypted data previously stored on the appliance's drives. If a drive suffers a failure during use that renders it inoperable and unable to be erased, we physically destroy the affected physical media. For more information on our media sanitization processes, see Ensuring Safe and Secure Media Sanitization.
You can request a wipe certificate for proof that we've securely sanitized the appliance media within 4 weeks after your data is available within Cloud Storage.
Transfer Appliance refurbishment
Once we've destroyed your data on the appliance you returned, we prepare to ship the appliance out to the next customer. The following is a summary of how we refurbish each appliance after media sanitization:
We partition the drives on the appliance. Media sanitization also destroys our data partitions, so we start fresh each time.
Then we reformat the drives, preparing them to store data and the appliance's software.
Next, we install the appliance's software, and apply any necessary updates.
Finally, we package and prepare to ship the appliance to the next customer.