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Windows Device Lock/Unlock Behavior with BitLocker Policies

Swif’s Device Lock command on Windows leverages BitLocker to enforce a full-disk lock and shutdown. The exact behavior depends on:

  • Windows Edition (Home vs. Pro)

  • Existence of a BitLocker policy on the C: drive

  • Presence of a TPM (Trusted Platform Module)


Context

For device encryption, Swif uses BitLocker, which supports the following protectors:

  • Password – A user-defined password set by the user. The TPM password is a user-defined password, and it’s used when the device is encrypted in a non-TPM device.

  • Numerical Password – A system-generated 48-digit recovery key. It’s used to unlock the device when the device is locked.

  • TPM – A hardware security chip that unlocks the drive automatically at boot.

Remote Device Lock Flow: When a lock command is sent, the agent enforces the Numerical Password on the next boot, regardless of whether the device has a TPM chip. This requires the 48-digit key to unlock the device.

To keep the disk encrypted after the lock, a second protector is maintained:

  • TPM-enabled devices → TPM remains as the ongoing protector.

  • Non-TPM devices → A user-defined Password is used instead. The TPM password is a user-defined password, and it’s used when the device is encrypted in a non-TPM device. The disk needs a password to encrypt it, and it’ll be used on every boot after unlock.


Below is a summary of the lock and unlock scenarios you may encounter.


1. Windows Home Edition

  • BitLocker support: Not available

  • Lock behavior: Ignored (no effect)

  • Unlock behavior: N/A


2. Windows Pro with Existing BitLocker Policy

TPM Present?

Lock Action

Unlock Behavior

Yes

Immediately shuts down the device (lock enforced)

Enter the recovery key once; the drive remains unlocked on subsequent boots without re-prompting.

No

Immediately shuts down the device (lock enforced)

Enter the recovery key once. User-defined Password is required for future boot.

Scenario detail: Swif issues the lock command, BitLocker shuts down the PC, and on TPM machines, the recovery key is only needed once; on non-TPM machines, the prompt repeats each time.


3. Windows Pro without Existing BitLocker Policy

TPM Present?

Encryption Action

Lock Action

Unlock Behavior

Yes

Initiates C: drive encryption, then shuts down

Shutdown after starting encryption

Enter the recovery key once; the drive remains encrypted but unlocked on subsequent boots.

No

Initiates C: drive encryption, then shuts down

Shutdown after starting encryption

Enter the recovery key once. User-defined Password is required for future boot.

Scenario detail: Swif’s lock command first triggers BitLocker encryption, then powers off. Unlocking once on TPM devices leaves the drive encrypted but accessible; without TPM, you must re-enter the key each time.


How to Unlock

  1. On the Swif dashboard devices table, click the locked Windows device and select Unlock.

  2. Retrieve the recovery key (48-digit numerical password) from the device details in the Swif dashboard.

  3. On the device, power it on and enter the recovery key at the BitLocker recovery screen.


Summary

Edition

BitLocker Policy

TPM

Device Lock

Device Unlock

Home

Any

N/A

Unsupported

N/A

Pro

Exists

Yes

Immediate shutdown

Recovery key once; no further prompts

Pro

Exists

No

Immediate shutdown

Recovery key on every boot

Pro

Not exists

Yes

Start encryption + shutdown

Recovery key once; drive stays encrypted but unlocked thereafter

Pro

Not exists

No

Start encryption + shutdown

Recovery key on every boot; drive stays encrypted


Key Takeaways

  • Windows Home: Device Lock has no effect.

  • Windows Pro + BitLocker policy: Lock is immediate; unlock prompts vary by TPM.

  • Windows Pro without policy: Lock first initiates encryption, then shuts down; unlock behavior again depends on TPM.

These behaviors ensure that device locks via Swif enforce full-disk security on Pro machines while gracefully handling the lack of BitLocker support on Home editions.

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