Windows 7 / Getting Started

TPM with PIN (Require PIN At Every Startup)

This requirement prevents the computer from starting until the user types a personal identification number (PIN), as illustrated in Figure below. This helps to protect the data in the event the computer is stolen while shut down. You should never use PINs to protect computers that need to start automatically without a human present, such as computers that are configured to start up for maintenance or backup purposes or computers that act as servers.

For better security, require users to type a PIN to authenticate them to TPM

Note Be sure to change your PIN frequently. Although Trusted Computing Group (TCG)-compliant TPMs offer protection from password-guessing attacks by forcing the user to wait between attempts, laptop keys show wear. This is especially true if you enter the PIN using your rarely used function keys (on most keyboards, you can use the standard number keys as well). If you use the same PIN for years, the keys in your PIN may show more wear than other keys, allowing a sophisticated attacker to guess the characters in your PIN, thus reducing the number of keys the attacker needs to guess. To minimize this risk further, use a long PIN and use the same key multiple times in your PIN.

When requiring a PIN, the computer's TPM hardware forces a non-resettable delay between PIN entry attempts (the exact delay varies between TPM vendors). Because of this delay, a four-digit PIN might take an entire year to crack. Without this delay, a random four-digit PIN could be cracked in less than a day. Because of this password-guessing weakness when a delay is not enforced by TPM, BitLocker does not allow PIN authentication on computers that do not have TPM hardware.

PIN Authentication

In this authentication scenario, the administrator sets up a PIN when BitLocker is turned on. BitLocker hashes the PIN using SHA-256. The resulting nonreversible hash is used as authorization data sent to the TPM to seal the VMK. The VMK is now protected by both the TPM and the PIN. To unseal the VMK, the user enters the PIN when the computer starts, the PIN is hashed, and the result is submitted to the TPM. If the submitted hash and other platform configuration registers (PCRs) are correct (proving that the user entered the same PIN), the TPM unseals the VMK.

The following authentication techniques are available regardless of whether the computer has a TPM.

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In this tutorial:

  1. Managing Disks and File Systems
  2. Overview of Partitioning Disks
  3. How to Choose Between MBR or GPT
  4. Converting from MBR to GPT Disks
  5. GPT Partitions
  6. Choosing Basic or Dynamic Disks
  7. Working with Volumes
  8. How to Create a Simple Volume
  9. How to Create a Spanned Volume
  10. How to Create a Striped Volume
  11. How to Resize a Volume
  12. How to Delete a Volume
  13. How to Create and Use a Virtual Hard Disk
  14. File System Fragmentation
  15. Backup And Restore
  16. How File Backups Work
  17. File and Folder Backup Structure
  18. How System Image Backups Work
  19. How to Start a System Image Backup from the Command Line
  20. How to Restore a System Image Backup
  21. System Image Backup Structure
  22. Best Practices for Computer Backups
  23. How to Manage Backup Using Group Policy Settings
  24. Previous Versions and Shadow Copies
  25. How to Manage Shadow Copies
  26. How to Restore a File with Previous Versions
  27. How to Configure Previous Versions with Group Policy Settings
  28. Windows ReadyBoost
  29. BitLocker Drive Encryption
  30. How BitLocker Encrypts Data
  31. How BitLocker Protects Data
  32. TPM with External Key (Require Startup USB Key At Every Startup)
  33. TPM with PIN (Require PIN At Every Startup)
  34. TPM with PIN and External Key
  35. BitLocker To Go
  36. BitLocker Phases
  37. Requirements for Protecting the System Volume with BitLocker
  38. How to Enable the Use of BitLocker on the System Volume on Computers Without TPM
  39. How to Enable BitLocker Encryption on System Volumes
  40. How to Enable BitLocker Encryption on Data Volumes
  41. How to Manage BitLocker Keys on a Local Computer
  42. How to Manage BitLocker from the Command Line
  43. How to Recover Data Protected by BitLocker
  44. How to Disable or Remove BitLocker Drive Encryption
  45. How to Decommission a BitLocker Drive Permanently
  46. How to Prepare AD DS for BitLocker
  47. How to Configure a Data Recovery Agent
  48. How to Manage BitLocker with Group Policy
  49. The Costs of BitLocker
  50. Windows 7 Encrypting File System
  51. How to Export Personal Certificates
  52. How to Import Personal Certificates
  53. How to Grant Users Access to an Encrypted File
  54. Symbolic Links
  55. How to Create Symbolic Links
  56. How to Create Relative or Absolute Symbolic Links
  57. How to Create Symbolic Links to Shared Folders
  58. How to Use Hard Links
  59. Disk Quotas
  60. How to Configure Disk Quotas on a Single Computer
  61. How to Configure Disk Quotas from a Command Prompt
  62. How to Configure Disk Quotas by Using Group Policy Settings
  63. Disk Tools
  64. EFSDump
  65. SDelete
  66. Streams
  67. Sync
  68. MoveFile and PendMoves