How LockPad protects your notes, what it cannot protect against, and how it was reviewed. For everyday use, see the user guide.

• Encryption
• Your master password
• Saving
• Locking
• Closing and signing out
• Clipboard
• Screenshots and screen sharing
• Files and paths
• Crash reports
• What LockPad does not protect against
• Security reviews
• Why LockPad exists

These settings are applied again on every save: if another program weakens a notebook's encryption or key-derivation settings, LockPad restores them the next time it saves. Every save also gets a fresh random salt and encryption IV.

KeePass's optional native helper library (KeePassLibN) is never loaded, so a copy of that DLL planted next to a notebook can never see your master key.

• The password goes to the KeePass library as raw UTF-8 bytes. Every temporary copy LockPad itself makes is wiped from memory as soon as it is no longer needed. The strength meter (part of the KeePass library) and Windows' own text handling can leave fragments in memory that cannot be wiped.
• Passwords with any characters work, including accented letters, Cyrillic and symbols.
• A wrong password shows "Wrong password or key file." Nothing is ever written after a failed unlock.

Every save, whether from Ctrl+S, on lock or on close, follows the same steps:

1. Refuse if the notebook is read-only.
2. Check whether another program changed the file. If it did, Ctrl+S and closing ask: Overwrite, Save As or Cancel. Overwrite replaces the file only if it is still this notebook: it opens with your password and key file, is a LockPad notebook, and, when both carry one, has the same notebook id. A different notebook with the same password is never overwritten. A save on lock asks nothing: it keeps your changes in memory behind the unlock screen, with a warning.
3. Write the notebook to a new temporary file in the same folder and flush it to disk.
4. Re-open that file with your password and compare every note with what is in memory. If anything differs, discard it. Your real file has not been touched.
5. Swap in the new file in one step. The old file becomes the backup private.kdbx.bak, replacing the previous backup.

If saving fails (a read-only file, a full disk, a locked file), your notebook and its .bak stay byte-for-byte unchanged and your edits stay in memory. If the final swap fails halfway, nothing is lost: the previous version is kept as the .bak and the verified new copy as a .tmp file, and the error message names both. Saving with no changes writes nothing, so it never replaces your backup.

An existing .bak that is not this notebook's own (for example your own copy with that name, or another notebook's) is never overwritten: LockPad keeps it as private.kdbx.bak.kept-<date> and says so in the status bar. A .bak counts as this notebook's own only if it opens with the same password and key file, is a LockPad notebook, and, when both files carry one, has the same random notebook id. If another program has the .bak open, the save fails with a message naming it and nothing is changed; save again.

To check a file it did not just write (the .bak, or a changed notebook you chose to overwrite), LockPad must derive its key. It reads the file once and first checks its key settings: a file with heavier settings than your notebook's own is never test-opened. It is not overwritten either: a .bak is kept aside, and Overwrite is refused with a message pointing to Save As. A crafted file therefore cannot freeze LockPad with your notes on screen.

• LockPad locks after a period with no keyboard or mouse input in its windows: 5 minutes by default, adjustable from 1 to 60. Input in LockPad's own dialogs counts too; input in the standard Windows boxes (file picker, "file changed" question, error messages) does not, because LockPad cannot observe it.
• Ctrl+L locks at once. LockPad also locks at once when Windows locks (Win+L, switching user, a remote disconnect) and before sleep or hibernation. Just before sleep your notes are hidden and the clipboard cleared at once; the save and lock follow, and finish after waking if the sleep cut them off.
• Before locking, unsaved changes are saved. That save takes a few seconds, so the idle lock and the lock after sleep first hide your notes and clear the clipboard, then save and lock a second or two later. A key press or click at that moment is ignored; it never changes your notes. If the save fails, your changes are held in memory behind the unlock screen, with a warning; your password restores them. Wrong attempts there wait 1, 2, 4, then 8 seconds.
• If the lock becomes due while one of LockPad's dialogs is open, your notes are hidden at once ("Locked - close the open dialog to finish locking.") and the clipboard is cleared; the lock finishes when the dialog closes. A New note, Rename or Delete answered after that point is ignored, because it may not have been you.
• Changing the Windows clock cannot postpone the lock.

• Closing the window saves your changes first. If that fails, you choose: Save As..., Close without saving (with a confirmation that defaults to No) or Cancel (the default).
• Signing out of or restarting Windows saves unsaved changes quietly first. If that fails, LockPad refuses the sign-out and keeps your changes in memory: behind the lock screen, or in the editor while one of LockPad's dialogs is open. If Windows forces the restart anyway ("Restart anyway", an update deadline), those unsaved changes are lost.

• Text you copy or cut in LockPad is marked so that Windows clipboard history (Win+V) and the cloud clipboard skip it.
• It is cleared after 20 seconds (adjustable from 5 to 120), when you lock, and when you close LockPad. On exit LockPad keeps trying for up to 20 seconds, because Windows' clipboard history service sometimes holds the clipboard briefly.
• LockPad only clears text it put there itself; something you copy in another program afterwards is left alone.
• Dragging selected text out of the editor is blocked (and so, deliberately, is drag-to-move inside it). Paste works as normal.

• While Hide LockPad from screenshots and screen sharing is on (the default), every LockPad window asks Windows to leave it out of captures. In a screenshot (Win+Shift+S, Print Screen), a recording or a shared screen (Teams, Zoom, Discord, OBS) the window does not appear; on Windows 10 before version 2004 it appears as a black box.
• This protects against showing your notes by accident, for example in a forgotten screen share, and against ordinary capture tools. It is not a guarantee: Microsoft describes it as unlike a security feature. It does not stop malware on your PC, a phone camera, or someone looking over your shoulder.
• Not covered, because Windows draws them as separate windows: menus, drop-down lists, tooltips, Windows' own error and warning boxes, and the Open/Save dialogs. None of these shows note text; error boxes can show file paths. The candidate list of an input method (for example Japanese or Chinese) and Windows typing suggestions show what you type and are not covered either. The window title (your notebook's file name) can show on the taskbar and in Alt+Tab.
• When LockPad runs inside Remote Desktop, a virtual machine or Citrix, the computer you connect from can still capture it. Virtual or wireless displays (Miracast, screen-extension apps) count as monitors and are not protected.
• To take screenshots of LockPad yourself, turn it off in Settings.

• Only notebooks on this PC's local drives are accepted. Network shares and mapped network drives are refused for opening and saving. A local folder that is itself a link to a network share is not detected.
• Special Windows path forms (\\?\, \\.\, \??\) are refused.
• A notebook reached through a symbolic link opens read-only, because saving through the link would break it.
• KDBX files LockPad did not create (for example your KeePassXC password database) and backup copies (*.bak, *.bak1...) open read-only, and you cannot save a notebook under a backup-style name. LockPad never writes to a file without its own notebook marker.

On startup, LockPad excludes itself from Windows Error Reporting for your user account and tells Windows to leave its memory out of any crash report that is still made, so a crash does not put your notes in a crash file. To undo it, delete the value LockPad.exe under HKCU\Software\Microsoft\Windows\Windows Error Reporting\ExcludedApplications.

Windows itself can still write memory to disk: a blue-screen crash dump, the page file and the hibernation file. No program can switch those off. Turn on BitLocker for your system drive (Windows 10/11 Pro) to keep them encrypted.

These limits are deliberate or unavoidable:

• Malware already on your PC. A keylogger or a program that reads other programs' memory can capture what you type and see. This is out of scope for any notepad.
• A forgotten master password or a lost key file. The encryption has no back door; nobody can recover them.
• Screen capture by a determined attacker. Capture hiding stops ordinary capture tools, not a camera or malware aimed at LockPad.
• Note text in memory. While a notebook is unlocked, your notes exist as ordinary text in LockPad's memory, which cannot be reliably wiped. This includes changes held behind the lock screen after a failed save. Locking hides and releases your notes but does not erase them from memory: copies can remain until LockPad exits. Close LockPad when you leave the PC for long.
• Memory that Windows writes to disk. Crash dumps, the page file and the hibernation file can contain open notes. Use BitLocker.
• Note titles are not secret. Titles appear in the notes list and in the delete confirmation. Never put a secret in a title.
• The clipboard after a forced kill. If LockPad is killed (for example from Task Manager) or the PC loses power, copied text can stay on the clipboard. Third-party clipboard managers may ignore Windows' history exclusion.
• Mistakes older than your last save. The .bak holds only the version before your last save. Keep your own copies on a separate USB stick or drive.
• Very large notes. A note over about 3 million characters is still saved and backed up, but KeePass's per-note version history (6 MiB) cannot hold it.
• Opening a hostile file. A .kdbx file crafted with extreme key settings can keep the unlock screen on "Unlocking..." indefinitely or run out of memory. Nothing is written and no notebook is open at that point (switching notebooks saves and closes the current one first); close LockPad from Task Manager. Only open notebooks you made yourself.
• Hard links. Saving through a hard link breaks the link: the other name keeps the old version (after a password change, with the old password). Open the original file instead.
• Someone who can change this source code. The integrity check on the vendored KeePass library catches accidental changes, not someone who changes both the library and its checksum file. To check it yourself: download the official KeePass 2.61.1 source package, verify its SHA-256 against keepass.info, and compare its KeePassLib folder with lib/KeePassLib here.

LockPad's code was reviewed and attacked by AI agents (Claude): a reviewer checks each change against its design, and a red team tries to break it with concrete inputs and event sequences. This is not a third-party audit.

Each change was attacked again after its fixes until no Critical, High or Medium finding remained. The re-attacks of 2026-10-22, including a final attack on their own fixes, are in 2026-10-22. Low findings from the last attack of each change were fixed with tests or accepted with a reason, as listed in the records. Some red-team passes reasoned from the source instead of running code; their test ideas became automated tests.

LockPad started as a replacement for Crypto Notepad, a small encrypted notepad for Windows. Its source code (version 1.7.3) has weaknesses that matter for private keys and PIN codes: it overwrites the file in place (an interrupted save can leave it empty), derives its key with SHA-1 and only 1,000 iterations, has no integrity check (a damaged file can decrypt into garbage), and lets copied text reach Windows clipboard history.

The usual advice is a password manager such as KeePassXC. Its protection is excellent, but it is built for password entries, not for writing and reading notes. LockPad gives you a notepad with the same file format and protection.