How-to

How to store scans of sensitive documents securely

Why scanned copies deserve the same care as the originals

A scanned passport, bank statement or payslip contains much of the same information as the paper document, often in a format that is easier to copy, forward or lose track of by accident. A phone full of photographed documents, or a folder of PDFs sitting in a downloads folder, can end up more exposed than the originals in a drawer.

None of the steps below are specific to any one application or process — they are general digital security practice that applies to storing any sensitive personal document, drawn from widely published guidance such as the National Cyber Security Centre's top tips for staying secure online. What a particular application needs is a separate question, covered by the current guidance on GOV.UK or by an IAA-registered adviser or SRA-regulated solicitor.

Locking down the device and using strong, unique passwords

Most phones, tablets and laptops offer a passcode, fingerprint or face unlock combined with full-device encryption, which usually only needs switching on once in the device's settings. This means that if the device is lost or stolen, whoever picks it up generally cannot simply open the photo gallery or file storage and see what is inside.

• Turning on a screen lock and device encryption, rather than leaving a device unlocked or set to auto-open.
• Using a strong, unique password for any account that stores or can access document copies — not one reused from another site.
• Storing passwords in a reputable password manager rather than a note, spreadsheet or sticky note, which tends to make unique passwords easier to keep track of.

Two-step verification and choosing where copies live

Two-step verification (sometimes called two-factor authentication, or 2FA) adds a second check, such as a code sent to a phone, on top of a password. Turning this on for email, cloud storage and any app used to store document copies means a leaked password on its own is usually not enough to get in.

• Turning on two-step verification wherever it is offered, particularly for email and cloud storage accounts, since email is often the way into everything else.
• Choosing storage with encryption built in, rather than an unencrypted shared drive or a folder with no access control.
• Being cautious about which apps are given access to photos or files, and checking permissions occasionally rather than granting access once and forgetting about it.

Keeping a backup, and sharing copies safely

Relying on a single copy, on a single device, tends to be risky — a lost phone or a failed hard drive can mean starting again from scratch. A second copy, kept somewhere separate such as encrypted cloud storage or an encrypted USB drive stored safely offline, gives a way back if the main copy is lost or damaged.

• Keeping at least one backup copy somewhere separate from the main device, ideally encrypted.
• Avoiding sending scans as plain email attachments over public Wi-Fi, or to anyone whose identity has not been confirmed through a separate channel.
• Treating unexpected messages that ask for a document scan — by text, email or phone — with caution, since this is a common phishing approach; confirming the request independently before sending anything.

Where a document does need to be shared, a link with an expiry date or a password-protected file tends to leave less exposed than an attachment that can be forwarded on indefinitely.

Removing old copies once they are no longer needed

Copies of sensitive documents have a way of spreading: a scan saved to a downloads folder, then emailed to another device, then left on a printer or a shared computer. Each extra copy is another place the information sits, so clearing out copies that are no longer needed tends to reduce the overall exposure.

• Checking downloads folders, email attachments, messaging apps and cloud photo libraries for stray copies once a document has been filed somewhere secure.
• Clearing scans left on a shared or public device, such as a library computer or a work printer's memory.
• Emptying the device's deleted-items or trash folder after removing a file, since some systems keep a deleted copy for a period afterwards.

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