Beginner's Tutorial

System Encryption

 Supported Systems

 Hidden Operating System

 Rescue Disk

Plausible Deniability

 Hidden Volume

  Protection of Hidden Vol.

  Security Requirements

 Hidden Operating System



Hardware Acceleration

Encryption Algorithms





Hash Algorithms




Technical Details


 Encryption Scheme

 Modes of Operation

 Header Key Derivation

 Random Number Gen.


 Volume Format Spec.

 Standards Compliance

 Source Code

TrueCrypt Volume

 Creating New Volumes

 Favorite Volumes

 System Favorite Volumes

Main Program Window

 Program Menu

 Mounting Volumes

Supported Systems

Portable Mode


Tokens & Smart Cards

Language Packs

Hot Keys

Security Model

Security Requirements

 Data Leaks

  Paging File

  Hibernation File

  Memory Dump Files

 Unencrypted Data in RAM

 Physical Security


 Multi-User Environment

 Authenticity and Integrity

 New Passwords & Keyfiles

 Password/Keyfile Change

 Trim Operation


 Reallocated Sectors


 Journaling File Systems

 Volume Clones

 Additional Requirements

Command Line Usage

Backing Up Securely


 Use Without Admin Rights

 Sharing over Network

 Background Task

 Removable Medium Vol.

 TrueCrypt System Files

 Removing Encryption

 Uninstalling TrueCrypt

 Digital Signatures



Issues and Limitations


Future Development


Version History



Security Requirements and Precautions >  Trim Operation Search


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Trim Operation

Some storage devices (e.g., some solid-state drives, including USB flash drives) use so-called 'trim' operation to mark drive sectors as free e.g. when a file is deleted. Consequently, such sectors may contain unencrypted zeroes or other undefined data (unencrypted) even if they are located within a part of the drive that is encrypted by TrueCrypt. TrueCrypt does not block the trim operation on partitions that are within the key scope of system encryption (unless a hidden operating system is running) and under Linux on all volumes that use the Linux native kernel cryptographic services. In those cases, the adversary will be able to tell which sectors contain free space (and may be able to use this information for further analysis and attacks) and plausible deniability may be negatively affected. If you want to avoid those issues, do not use system encryption on drives that use the trim operation and, under Linux, either configure TrueCrypt not to use the Linux native kernel cryptographic services or make sure TrueCrypt volumes are not located on drives that use the trim operation.

To find out whether a device uses the trim operation, please refer to documentation supplied with the device or contact the vendor/manufacturer.

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