NCryptOpenKey function (ncrypt.h)

Article
10/13/2021

The NCryptOpenKey function opens a key that exists in the specified CNG key storage provider.

Syntax

SECURITY_STATUS NCryptOpenKey(
  [in]  NCRYPT_PROV_HANDLE hProvider,
  [out] NCRYPT_KEY_HANDLE  *phKey,
  [in]  LPCWSTR            pszKeyName,
  [in]  DWORD              dwLegacyKeySpec,
  [in]  DWORD              dwFlags
);

Parameters

[in] hProvider

The handle of the key storage provider to open the key from.

[out] phKey

A pointer to a NCRYPT_KEY_HANDLE variable that receives the key handle. When you have finished using this handle, release it by passing it to the NCryptFreeObject function.

[in] pszKeyName

A pointer to a null-terminated Unicode string that contains the name of the key to retrieve.

[in] dwLegacyKeySpec

A legacy identifier that specifies the type of key. This can be one of the following values.

Value	Meaning
AT_KEYEXCHANGE	The key is a key exchange key.
AT_SIGNATURE	The key is a signature key.
0	The key is none of the above types.

[in] dwFlags

Flags that modify function behavior. This can be zero or a combination of one or more of the following values.

Value	Meaning
NCRYPT_MACHINE_KEY_FLAG	Open the key for the local computer. If this flag is not present, the current user key is opened.
NCRYPT_SILENT_FLAG	Requests that the key service provider (KSP) not display any user interface. If the provider must display the UI to operate, the call fails and the KSP should set the NTE_SILENT_CONTEXT error code as the last error.

Return value

Returns a status code that indicates the success or failure of the function.

Possible return codes include, but are not limited to, the following.

Return code	Description
ERROR_SUCCESS	The function was successful.
NTE_BAD_FLAGS	The dwFlags parameter contains a value that is not valid.
NTE_BAD_KEYSET	The specified key was not found.
NTE_INVALID_HANDLE	The hProvider parameter is not valid.
NTE_INVALID_PARAMETER	One or more parameters are not valid.
NTE_NO_MEMORY	A memory allocation failure occurred.

Remarks

A service must not call this function from its StartService Function. If a service calls this function from its StartService function, a deadlock can occur, and the service may stop responding.

For performance reasons, Microsoft software-based KSPs cache private key material in the Local Security Authority (LSA) for as long as a handle to the key is open. The LSA is a privileged system process. Therefore, other users cannot access this cached copy of the key unless the user possesses administrator privileges on the system. This behavior cannot be altered through configuration.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2008 [desktop apps \| UWP apps]
Target Platform	Windows
Header	ncrypt.h
Library	Ncrypt.lib
DLL	Ncrypt.dll

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