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Trusted APIs (Windows CE 5.0)

In addition to the original equipment manufacturer functions, the CeGetCurrentTrust and CeGetCallerTrust API functions enable a DLL to query the trust level of a calling application.

The following table shows the API functions that can be called only by trusted applications.

API API
AllocPhysMem CeSetMemoryAttributes
CeSetThreadPriority CeSetThreadQuantum
CheckPassword ContinueDebugEvent
CreateWatchDogTimer CryptUnprotectData
DebugActiveProcess DrWatsonClear
DrWatsonFlush DrWatsonGetSize
DrWatsonReadData DrWatsonWriteData
ForcePageout FreeIntChainHandler
FreePhysMem InterruptDisable
InterruptDone InterruptInitialize
KernelLibIoControl LoadDriver
LoadIntChainHandler LoadKernelLibrary
LockPages NTLMAddGroup
NTLMAddUserToGroup NTLMDeleteUser
NTLMEnumGroups NTLMEnumUser
NTLMGetGroupList NTLMGetUserList
NTLMRemoveGroup NTLMRemoveUserFromGroup
NTLMSetUserInfo OpenWatchDogTimer
PowerOffSystem ReadProcessMemory
ReadRegistryFromOEM RefreshWatchDogTimer
RegCopyFile RegReplaceKey
RegRestoreFile RegSaveKey
SetCleanRebootFlag SetCurrentUser
SetInterruptEvent SetKMode
SetPassword SetPasswordStatus
SetProcPermissions SetSystemMemoryDivision
SetUserData StartWatchDogTimer
StopWatchDogTimer Toolhelp32ReadProcessMemory
UnlockPages VirtualCopy
VirtualSetPageFlags WaitForDebugEvent
WriteProcessMemory WriteRegistryToOEM

The following table shows file-based API functions that are influenced by the SYSTEM attribute that can be set on a file. For more information, see File System Security.

API API
CreateFile CreateFileForMapping
CopyFile DeleteFile
DeleteAndRenameFile MoveFile
RemoveDirectory SetFileAttributes

The following table shows database API functions that are influenced by the SYSTEM attribute that can be set on a database. For more information, see Database Security.

API API
CeMountDBVol CeCreateDatabaseEx2
CeOpenDatabaseEx2 CeDeleteDatabaseEx
CeSetDatabaseInfoEx2  

In addition, the debug flags DEBUG_ONLY_THIS_PROCESS and DEBUG_PROCESS of the CreateProcess API are restricted. If these flags are used by a non-trusted application, the identified process will still launch but no debugging will occur.

Debug flags, DEBUG_ONLY_THIS_PROCESS and DEBUG_PROCESS, in the CreateProcess API are restricted as well.

The secure registry architecture in Windows CE allows only trusted applications that you have identified to modify keys and values in protected portions of the registry.

Because most of the registry is unprotected, original equipment manufacturers must place all-important registry information in one of the protected keys.

**Note   **All applications have read-only access to all registry keys and values.

In Windows CE, the following registry root keys and their subkeys are protected from untrusted applications:

  • HKEY_LOCAL_MACHINE\Comm
  • HKEY_LOCAL_MACHINE\Drivers
  • HKEY_LOCAL_MACHINE\HARDWARE
  • HKEY_LOCAL_MACHINE\Init
  • HKEY_LOCAL_MACHINE\Services
  • HKEY_LOCAL_MACHINE\SYSTEM
  • HKEY_LOCAL_MACHINE\WDMDrivers

Untrusted applications are also not allowed to modify protected data. They receive the ERROR_ACCESS_DENIED return value if they attempt to use the following registry functions:

  • RegSetValueEx
  • RegCreateKeyEx
  • RegDeleteKey
  • RegDeleteValue

Windows Mobile 5.0

In Windows Mobile 5.0 software there are additional APIs and registry root keys that are also protected from untrusted applications.

The following table shows the Extended Telephony Application Program Interface (ExTAPI) functions that can be called by trusted applications.

API API
lineGetGeneralInfo lineSetCallWaitingState
lineGetNumberCalls lineSetEquipmentState
lineGetUSSD lineSetGPRSClass
lineRegister lineSetHSCSDState
lineSendUSSD lineSetPreferredOperator
lineSetCallBarringPassword lineSetSendCallerIDState
lineSetCallBarringState lineUnregister

The following table shows the SIM Manager functions that can be called by trusted applications.

API API
SimChangeLockingPassword SimReadRecord
SimDeleteMessage SimSetLockingStatus
SimGetRecordInfo SimUnlockPhone
SimGetSmsStorageStatus SimWriteMessage
SimReadMessage SimWriteRecord

The following table shows the Short Message Service (SMS) functions that can be called by trusted applications.

API
SmsClearMessageNotification
SmsSetMessageNotification
SmsSetSMSC

The following table shows other functions that can be called by trusted applications.

API
Connection Manager function ConnMgrProviderMessage
Critical Process Monitor function CPMRegister (Reboot)

In Windows Mobile 5.0-based devices, the following registry root keys and subkeys are protected from untrusted applications in addition the list for Windows CE:

  • HKEY_LOCAL_MACHINE\Security
  • HKEY_CURRENT_USER\Security
  • HKEY_LOCAL_MACHINE\Loader

See Also

Trusted Environment Creation | Protected Registry Keys and Values | Database Security | Core OS Reference

Last updated on Thursday, February 02, 2006

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