A. Encrypting and compressing a file/folder is mutually exclusive, you can encrypt a file or compress it, not both.
To decrypt a file perform the following:
- Start Explorer
- Right click on the file/folder
- Select Properties
Click here to view image
- Under the General tab click Advanced
- Check the 'Encrypt contents to secure data'. Click OK
- Click Apply on the properties
- If you selected a file it will ask if you want to encrypt the parent
folder to prevent the file from becoming unencrypted during modification.
Click OK If you selected a folder if will ask if you want to encrypt
subfolders and files also. Click OK.
- Click OK to the main dialog
To decrypt repeat the above but unselect the box. If you decrypt a folder it will ask if you also want to decrypt all child folders and files.
Compression of an encrypted file will not save in most case. Encrypt compressed file makes sense.
There is a technical issue here. It is not because of reparse point. Neither compression nor encryption uses reparse point. The
reason we do not support both is backup\restore. We provide a way for backup operator to backup encrypted file. The operator has no way to read the
file in plaintext. The NTFS compression result depends on the disk cluster. If the backup source and the restore destination has the different cluster
size, NTFS could not restore the encrypted data because NTFS does not know how to understand the data.
Sparse and encryption.
Encryption is compatible with sparse. In other words, you can encrypt a sparse file and still keep it a sparse file.