AddUsersToEncryptedFile function (winefs.h)

Adds user keys to the specified encrypted file.


DWORD AddUsersToEncryptedFile(
  [in] LPCWSTR                      lpFileName,
  [in] PENCRYPTION_CERTIFICATE_LIST pEncryptionCertificates


[in] lpFileName

The name of the encrypted file.

[in] pEncryptionCertificates

A pointer to an ENCRYPTION_CERTIFICATE_LIST structure that contains the list of new user keys to be added to the file.

Return value

If the function succeeds, the return value is ERROR_SUCCESS.

If the function fails, the return value is a system error code. For a complete list of error codes, see System Error Codes or the header file WinError.h.


Starting with Windows 8 and Windows Server 2012, this function is supported by the following technologies.

Technology Supported
Server Message Block (SMB) 3.0 protocol No
SMB 3.0 Transparent Failover (TFO) No
SMB 3.0 with Scale-out File Shares (SO) No
Cluster Shared Volume File System (CsvFS) No
Resilient File System (ReFS) No

SMB 3.0 does not support EFS on shares with continuous availability capability.


For example code that uses this function, see Adding Users to an Encrypted File.


Requirement Value
Minimum supported client Windows XP Professional [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header winefs.h (include Windows.h)
Library Advapi32.lib
DLL Advapi32.dll
API set ext-ms-win-advapi32-encryptedfile-l1-1-1 (introduced in Windows 10, version 10.0.14393)

See also


File Encryption

File Management Functions