Security you can verify.
We're a security-first product, so we publish exactly what we do — and only claim what we can prove. Here is the real architecture, in the same words as our engineering docs.
Your clipboard is yours: no clipboard data leaves your Mac by default — AES-256-GCM encrypted, Secure-Enclave-wrapped on capable Macs, fully on-device, with an audit-logged chokepoint that always redacts the results agents and automations see.
Encrypted before it touches disk.
AES-256-GCM at rest
Every clipboard item is authenticated-encrypted with a unique nonce and salt — confidentiality and integrity on each record.
Per-item HKDF-SHA256 keys
Keys are derived per item from a random 256-bit master key (v2 envelope). Legacy v1 items stay decryptable via envelope versioning — no forced re-encryption.
Secure Enclave key wrapping
On Macs with a Secure Enclave, the master key is stored wrapped by a non-extractable enclave key that never leaves the hardware. Check which is active under Settings → Security → Key storage.
Keychain fallback, device-local
Macs without a Secure Enclave keep the master key in the Mac's data-protection keychain: this-device-only, non-synchronizable, and readable only while the Mac is unlocked. If macOS refuses that keychain, the key is kept in the login keychain, where those limits don't apply, and Settings → Security → Key storage says so.
Account key and Touch ID
A Copywarden Account's key stays on each signed-in Mac, wrapped by a separate non-extractable enclave key (Keychain-only on Macs without one), so sync resumes after a restart without your master password. That copy stays on the Mac, and Sign Out deletes it. With a master password, a new Mac needs that password or your Emergency Kit. An account without one, which signs in with Apple, GitHub or Google, needs its Emergency Kit on a new Mac unless the account key's iCloud Keychain backup is on (the default); then a Mac signed in to the same Apple Account opens it without the kit. A lost Mac can be signed out from another under Settings → Account & Sync. Opening your clipboard doesn't prompt you unless HIPAA or Banking mode's automatic logoff asks for Touch ID or your login password after inactivity. The encryption doesn't depend on any prompt.
On-device, opt-in telemetry
Secret detection, semantic search, content analysis and OCR run locally via Apple frameworks. No content is sent anywhere. Usage data only if you opt in; no ads, no data sale.
A clipboard that treats credentials like credentials.
Detection + redaction
Credentials, tokens and keys are recognized on-device and masked in the UI the moment they're captured.
Auto-expiry (TTL)
Detected secrets can auto-expire out of history, so a copied key doesn't linger for weeks.
Clipboard auto-clear
The system clipboard is cleared after a secret paste — the KeePassXC pattern — so it doesn't sit in the OS pasteboard.
Concealed paste-back
When Copywarden pastes a secret it tags the write org.nspasteboard.ConcealedType, so well-behaved clipboard tools skip it and it stays off Universal Clipboard — a best-effort community convention, not a guarantee.
Honors upstream markers — always
Concealed and transient flags from other apps are honored unconditionally — hard-coded, not a setting. One user-editable list, Don't Save Copies from These Apps, ships pre-seeded with 1Password, Bitwarden, LastPass, Keychain Access and Apple's Passwords app, plus any app with Banking or Wallet in its name, and each entry has its own switch. Copywarden re-marks its own secret paste-backs as concealed so clipboard tools that honor the convention skip them.
An agent can use your clipboard. What it sees is always redacted.
App Intents, Shortcuts and Spotlight route through a single security chokepoint, AgentAccessGuard, which redacts every result an agent sees (unconditional, no override), honors a kill-switch (turn off Allow Shortcuts and AI agents, or set it by admin policy, and agent access stops before any data is read), and audit-logs every access to a tamper-evident log — which tool, when, how many items, how many secrets withheld — never the content itself. It is the opposite of clipboard-to-cloud "AI memory."
Threat monitoring & screen safety
While Copywarden detects a screen capture, a recording or a video-call share, it hides your clips in the popup behind a banner, and shows them again when the capture stops. It detects the macOS screenshot and recording tool, recorder apps on a list it keeps, and shares from Zoom, Microsoft Teams, Webex and Google Meet in Chrome; detecting a share needs the optional Screen Recording permission. We don't claim invisibility: detection is best-effort, and a capture Copywarden cannot see is not hidden. Copywarden also asks macOS to leave its windows out of screen captures, and each capture tool decides whether to respect that. On Macs whose security level is High or Maximum, which is set from the Mac's hardware, it also watches for a debugger attached to it and closes the popup if it finds one.
Sync & data residency
Local-first by design: everything works with sync off, and no clipboard data leaves your Mac unless you opt in. Optional end-to-end encrypted sync (beta, off by default) carries only opaque AES-256-GCM ciphertext blobs, sealed on-device before upload — to Copywarden's servers by default, or to your private iCloud database if you pick that backend. Either way we cannot read them, because we never have a readable copy of the key.
Auditability
A tamper-evident, HMAC-chained audit log records access events — never content — and exports to JSON or CSV for your compliance review.
We'd rather under-promise than overstate.
Copywarden ships GDPR, HIPAA and Banking modes that enforce stricter content-retention caps (GDPR/HIPAA 7 days, Banking 3 days) and tag items for classification and audit context. Per-mode access-control and session enforcement are not yet wired — so we market only what we can currently prove: encrypted, on-device, offline, audit-logged. These are configurable controls and profiles, not a certification.
Formal, independent attestations are not claimed: SOC 2 is on our roadmap — we will pursue a Type II attestation when our enterprise customers require it, and we will not claim it until the report is issued. A BAA template is available for legal review; we don't sign BAAs for cloud-sync deployments today.
What is not encrypted
Copywarden encrypts your clips. Versions after 0.9.7 also encrypt the list of them: each clip's identifier, type, size, times, use count, pin state and category label, and the SHA-256 fingerprint that spots a repeat copy. Version 0.9.7 and earlier store that list without encryption, and a later version encrypts it the first time it opens it. A copy of the list that an earlier version set aside because it could not read it stays as it is until you clear all stored data in Settings. No version encrypts Copywarden's settings, which macOS keeps in its preferences store, its audit and compliance logs, the crash reports it keeps for a support request, or a file you export. It also keeps a few small bookkeeping files that hold nothing about your clips.
What we don't protect against
Honest threat models have edges. Copywarden protects your clipboard history against disk theft, at-rest reading by other apps, screen-share exposure, and agent over-reach. It cannot protect against malware running as your user while the app is unlocked, or a kernel-level keylogger — nothing in userspace can. And plainly: no independent audit yet, and no bug bounty yet. The full boundary — including what sync does and does not protect — is in the threat model.
Found something? We offer safe harbor.
We welcome good-faith security research. Contact details and scope live in our machine-readable /.well-known/security.txt (RFC 9116). Reports go to security@copywarden.com; our disclosure policy commits to a single, complete public notice — never a drip, with safe harbor for good-faith research.