WinVistaClub : De-Mystifying Windows Vista Registry

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De-Mystifying Windows Vista Registry

The Windows Registry is a directory which stores settings and options for the operating system for Microsoft Windows. It contains information and settings for all the hardware, operating system software, most non-operating system software, users, preferences of the PC, etc. Whenever a user makes changes to Control Panel settings, file associations, system policies, or most installed software, the changes are reflected and stored in the registry. The registry also provides a window into the operation of the kernel, exposing runtime information such as performance counters and currently active hardware. The Windows registry was introduced to tidy up the profusion of per-program INI files that had previously been used to store configuration settings for Windows programs. These files tended to be scattered all over the system, which made them difficult to track.

This Article explains the basics of Windows Vista Registry.

The Registry consists of the following 5 Root Keys:
HKEY_CLASSES_ROOT
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS
HKEY_CURRENT_CONFIG.

Root Keys contain SubKeys. Subkeys, may contain subkeys of their own too, and contain at least one value, called as its Default Value. A key with all its subkeys and values is called as a Hive.

The Registry is stored on the Disk as several separate Hive files. These Hive files are then read into memory every time Vista starts or when the User logs on. To see where the Hives are physically stored, see:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\HiveList

The Registry uses the following data types:

REG_SZ : The SZ indicates zero-terminated string. This is a variable-length string that can contain Unicode as well as ANSI characters.
REG_BINARY : It contains binary data. 0's & 1's.
REG_DWORD : This data type is a Double Word. It is, a 32-bit numeric value and can hold any number from 0 to 232.
REG_QWORD : This data type is a Quadruple Word. It is a 64-bit numeric value.
REG_MULTI_SZ : This data type contains a group of zero-terminated strings assigned to a single value.
REG_EXPAND_SZ : This data type is a zero-terminated string containing an unexpanded reference to an environment variable, like say, %SystemRoot%.

Vista's Registry Virtualization.

In Windows Vista, the Registry has been Virtualized, and hence unlike XP, does not tend to suffer from bloat.

Virtualization basically means that, applications are prevented from writing to System Folders in Vista's file system and ALSO to the 'machine wide keys' in the registry. However, this does not prevent standard user accounts from installing or running applications.

In Vista, the UAC utilizes the Registry Virtualization Feature, to redirect attempts to write to subkeys of

HKEY_LOCAL_MACHINE\Software

When an application attempts to write to this hive, Vista instead, writes it, to a per-user location,

HKEY_CLASSES_ROOT\VirtualStore\Machine\Software

This is done discreetly. No one gets to know that this is happening !

This is, in short Registry Virtualization, and it is a useful Security feature.

Incidentally, mention must also be made of another new technology underlying Vista : The Kernel Transaction Manager, which enables Transactional Registry. This feature enables a sort of a registry rollback. But it’s not implemented in Registry Editor. Instead, this feature is designed for use by developers who need to create robust applications using transactional processing.

How To Edit The Registry.

The primary tool in Windows Vista for working directly with the registry is Registry Editor. To access it, simply type regedit in Vista's Start Menu Search Bar and hit Enter ! You have to be doubly careful when working with the Registry, as there is no confirmation prompt or a click OK to save prompt. Changes made are directly incorporated.

Mention must specifically be made of

HKEY_LOCAL_MACHINE\System\CurrentControlSet

hive as the keys in this particular are so essential for Vista to start-up, that its backup is maintained, which you can restore when necessary, simply by booting in Safe Mode and selecting Last Known Good Configuration.

These Links For Further Reading May Also Interest You:
How To Back Up, Restore, Maintain the Vista Registry
How To Monitor Changes In The Vista Registry
How To Restrict or Restore Access to the Vista Registry
How To Lock Out Particular User from the Registry
How To Change Key Permissions in the Vista Registry