Client-side backup encryption
Cloud storage receives encrypted repository data, not readable customer files.
- Data encryption
- AES-256-GCM
- Encryption location
- Customer device
- Storage contents
- Encrypted repository objects
The vault key belongs to the client
The desktop app generates a random per-account master key. It wraps that key locally in a versioned envelope and uses it to open the Kopia repository. SaveState’s hosted API stores the encrypted envelope and a one-way possession verifier, not the plaintext master key.
Short-lived, account-scoped storage credentials authorize repository access. Possessing storage objects or an API database record is not enough to decrypt customer backup contents.
How encrypted backup and restore work
The Windows client reads the selected files, uses Kopia to compress and deduplicate their content, and encrypts repository data before it is uploaded. The storage allowance is measured against the resulting encrypted repository footprint, rather than the original size of every file version.
During a restore, the client opens the repository with the matching vault key and turns the encrypted backup into usable files on your device. You can restore to a separate folder first to check a version without overwriting your working files.
A precise security claim
SaveState calls this client-side encryption. The account password is still sent to the SaveState API over HTTPS for account authentication, so the product does not claim strict zero-knowledge authentication. The backup contents and their decryption material have a separate client-owned boundary.
Common questions
What does end-to-end encryption mean for backup contents?
End-to-end encrypted backup, often shortened to E2EE backup, means backup contents are encrypted before reaching cloud storage and decrypted by a client with the matching key. SaveState uses client-side encryption for this backup-content boundary; account authentication is a separate process.
Can SaveState or the storage provider read my backed-up files?
The hosted service does not receive the plaintext vault master key. Stored repository objects and the encrypted key envelope alone are not enough to decrypt backup contents. The client needs the matching vault key.
Does resetting my account password unlock my backups?
Account recovery and vault recovery are separate. An existing envelope vault needs the previous vault password, its offline vault recovery key, or a matching remembered-device key after an account password reset. An email link or authenticator code does not decrypt the backup.
Is this zero-knowledge account authentication?
No. The account password is sent to the SaveState API over HTTPS to authenticate the account. Backup-content encryption is client-side, and the hosted service stores wrapped vault material rather than the plaintext master key.
Put this feature into a recovery plan
Install SaveState on Windows, protect a representative data set, and test the restore before it is urgent.
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