/B | Abort if an error is encountered. By default, CIPHER continues executing even if errors are encountered. |
/C | Displays information on the encrypted file. |
/D | Decrypts the specified files or directories. |
/E | Encrypts the specified files or directories. Directories will be marked so that files added afterward will be encrypted. The encrypted file could become decrypted when it is modified if the parent directory is not encrypted. It is recommended that you encrypt the file and the parent directory. |
/H | Also displays files with the hidden or system attributes (which are excluded by default). |
/K | Creates a new certificate and key for use with EFS. If this option is chosen, all the other options will be ignored. |
/N | This option only works with /U. This will prevent keys being updated. This is used to find all the encrypted files on the local drives. |
/R | Generates an EFS recovery key and certificate, then writes them to a .PFX file (containing certificate and private key) and a .CER file (containing only the certificate). |
/P | Creates a base64-encoded recovery-policy blob from the passed-in certificate. This blob can be used to set DRA policy for MDM deployments. |
/S | Performs the specified operation on the given directory and all files and subdirectories within it. |
/U | Tries to touch all the encrypted files on local drives. This will update user's file encryption key or recovery keys to the current ones if they are changed. This option does not work with other options except /N. |
/W | Removes data from available unused disk space on the entire volume. If this option is chosen, all other options are ignored. The directory specified can be anywhere in a local volume. If it is a mount point or points to a directory in another volume, the data on that volume will be removed. |
/X | Backup EFS certificate and keys into file filename. If efsfile is provided, the current user's certificate(s) used to encrypt the file will be backed up. Otherwise, the user's current EFS certificate and keys will be backed up. |
/Y | Displays your current EFS certificate thumbprint on the local PC. |
/ADDUSER | Adds a user to the specified encrypted file(s). If CERTHASH is provided, cipher will search for a certificate with this SHA1 hash. If CERTFILE is provided, cipher will extract the certificate from the file. If USER is provided, cipher will try to locate the user's certificate in Active Directory Domain Services. |
/FLUSHCACHE | Clears the calling user's EFS key cache on the specified server. If servername is not provided, cipher clears the user's key cache on the local machine. |
/REKEY | Updates the specified encrypted file(s) to use the configured EFS current key. |
/REMOVEUSER | Removes a user from the specified file(s). CERTHASH must be the SHA1 hash of the certificate to remove. |
Notes for some command line options
/K
By default, /k creates a certificate and key that conform to current group policy.
If ECC is specified, a self-signed certificate will be created with the supplied key size.
/R
An administrator may add the contents of the .CER to the EFS recovery policy to create the recovery key for users, and import the .PFX to recover individual files. If SMARTCARD is specified, then writes the recovery key and certificate to a smart card. A .CER file is generated (containing only the certificate). No .PFX file is generated.
By default, /r creates an 2048-bit RSA recovery key and certificate.
If ECC is specified, it must be followed by a key size of 256, 384, or 521.
/W
When encrypting files, the Encrypting File System first makes a backup copy of the file in order to restore the the data in acase an error occurs during the encryption process.
After the encryption is complete, this backup copy is deleted. Thus, it can be recovered with «undelete utilities»
The /W option is intended to overwrite such backup copies to increase protection.