Security: How Custody Note Protects Your Data
Custody Note keeps attendance notes in an AES-256-GCM encrypted database on your Windows PC or Mac. During the free beta, sign in with your email to sync your notes across up to 5 computers. Records are encrypted on your device before upload, and an encrypted copy of your database key is held so your other computers can read them. Managed cloud backup is planned for Pro after beta. This page sets out exactly who can access what.
Criminal defence practitioners handle some of the most sensitive personal data in the legal system: custody records, disclosure details, consultation notes, and client instructions given under legal professional privilege. This page describes how the current version of Custody Note protects that data, including the trade-offs, so that you and your firm can make an informed risk assessment.
Encryption on your device
Attendance records, attachments and settings are stored in a local database encrypted with AES-256-GCM. The 256-bit database key is generated randomly on your device and protected by your operating system's credential store (Windows DPAPI or the macOS Keychain). Records aren't kept in a browser cache or in plain-text files.
Because the key is tied to your operating-system account, anyone who can sign in to your OS account can open Custody Note's data. Use full-disk encryption (BitLocker on Windows, FileVault on macOS), a strong OS password and an automatic screen lock. Custody Note also has an idle session lock.
Cross-device sync and key recovery
During the free beta, sign in with your email to sync your notes across up to 5 computers. Each record is encrypted with your database key on your device before upload, and our server adds a second layer of encryption at rest. Sync requests are authenticated with your licence key and an activated device, and individual devices can be revoked. Managed cloud backup is planned for Pro after beta.
So that a second or replacement device can read your synced records, the app uploads a copy of your database key that's encrypted with a key derived from your licence key. Defence Legal Services issues and stores licence keys, so this is not a zero-knowledge or end-to-end encrypted design: it's technically possible for us to recover the key and decrypt synced records. We don't access record content as part of operating the service. If your risk assessment requires that we can't technically decrypt your records, don't sign in to sync, and keep your own encrypted backups.
Optional cloud backup
Managed cloud backup is optional. When enabled, encrypted snapshots of your database (encrypted on your device with the same key) are stored in Amazon Web Services' London region (eu-west-2). To restore on a new device you need the database key, which the app obtains from your recovery password (if you set one on the old device and still have its recovery file) or from the licence-key-protected key copy described above.
Custody Note also supports local backups and backups to a folder you choose (for example a OneDrive or Dropbox folder). Those copies are encrypted with the same key and are under your control.
What the app sends to us and to others
- Licence checks: your licence key, a device identifier and the app version, to activate and validate your licence.
- Cross-device sync and cloud backup (paid): encrypted records or database snapshots and the encrypted key copy described above.
- Usage statistics: a small daily ping (app version, platform, licence tier and a hashed device identifier). It contains no case data.
- Optional features: postcode lookup sends the postcode you enter; optional AI features send only the text you confirm, to OpenAI, using your own API key.
We don't sell data, and the app doesn't send case content to advertising or analytics networks.
Recovery password
You can set an optional recovery password. It protects a copy of your database key stored on that device, so you can unlock your data if the operating-system credential store becomes unavailable (for example after moving data to another computer). We never receive your recovery password. If you have no recovery password, no cloud key copy and no usable backup, encrypted data can't be recovered.
Legal professional privilege
Attendance notes created during police station attendances are, in most circumstances, protected by legal professional privilege. Encryption on your device and in transit supports confidentiality, but privilege is a legal concept, not a software feature, and no application can guarantee it in all circumstances. Take the cross-device sync key arrangement above into account in your own risk assessment.
Data protection roles
Under UK GDPR you (or your firm) are the controller of the personal data in your attendance notes. Defence Legal Services Ltd processes account and licence data, and, if you use cross-device sync or cloud backup, stores your encrypted records and encrypted key copy on your behalf. If you use Custody Note without sync or cloud backup, your attendance-note content isn't sent to us. See our privacy policy for details, and contact us if your firm needs data processing terms.
If a device is lost or stolen
Revoke the device's licence and sync access straight away (from another device's Settings, or by contacting support), tell your firm, and consider whether a report to the ICO is required. Whether data on the lost device is readable depends largely on your operating-system security: with full-disk encryption and a strong OS password, the encrypted database is very difficult to access. When Pro launches, you can restore your records to a new device from sync or cloud backup.
What we don't claim
- Custody Note hasn't yet had an independent penetration test, and Custody Note itself holds no security certifications (such as ISO 27001 or Cyber Essentials). Certifications held by our infrastructure providers cover their infrastructure, not Custody Note.
- The desktop app doesn't have multi-factor authentication; access is based on your operating-system account, your licence and your activated devices.
- No software is unhackable. These measures reduce risk; they don't eliminate it.
GDPR considerations
- Data minimisation: Custody Note stores what you enter. Usage statistics contain no case data.
- Storage limitation: you control retention and deletion of records on your devices; deleting a synced record also removes it from sync.
- Security of processing: AES-256-GCM encryption on your device, encrypted sync and backups, HTTPS in transit.
- Data portability: PDF export and local backups mean you aren't locked in.
Frequently asked questions
Is my data stored in the cloud by default?
Attendance records are stored in an encrypted database on your computer and the app works without internet. During the free beta, sign in with your email to sync your notes across up to 5 computers. Records are encrypted on your device before upload. Managed cloud backup is planned for Pro after beta.
Can Defence Legal Services Ltd read my notes?
Records on your computer are encrypted with a key generated on that device. If you sign in and sync, we store your records encrypted plus a copy of your database key that's encrypted with a key derived from your licence key. Because we issue and store licence keys, this isn't a zero-knowledge design: it's technically possible for us to decrypt synced records. We don't access record content as part of running the service. If you need records that we can't technically decrypt, don't sign in to sync, and keep your own encrypted backups.
What encryption does Custody Note use?
AES-256-GCM for the local database, synced records and backup snapshots, with a random 256-bit key generated on your device. Connections to custodynote.com use HTTPS (TLS).
Where is cross-device sync data stored?
Synced records and the encrypted copy of your database key are stored by our sync service on custodynote.com's cloud infrastructure. Records are encrypted on your device before upload and are encrypted again at rest on the server.
Where is cloud backup data stored?
Optional cloud backup snapshots are encrypted on your device and stored in Amazon Web Services' London region (eu-west-2).
What should I do if my device is stolen?
Tell your firm, revoke the device's licence and sync access (Settings or contact support), and assess whether you need to report to the ICO. The local database is encrypted, but its key is protected by your operating-system account, so full-disk encryption (BitLocker or FileVault) and a strong OS password are essential.
Ready to see it in practice? Download Custody Note for Windows or Mac.