Linux: Create an encrypted filesystem inside a file

Create encrypted FS in a file

#Create a file and allocate its size : here 1GB

dd if=/dev/zero of=encrypteddrive bs=1024 count=1048576

#Setup the encrypted file

cryptsetup -y luksFormat encrypteddrive

(enter passphrase and confirm)

#Open the Encrypted device

sudo cryptsetup luksOpen encrypteddrive secretdata

 (enter password)

 

 #Create an EXT4 filesystem inside the encrypted file

sudo mkfs.ext4 /dev/mapper/secretdata

#Create a directory to be the mountpoint

mkdir ../mp-encrypted

#Mount the encrypted FS 

sudo mount /dev/mapper/secretdata ../mp-encrypted/

#After use, unmount the encrypted FS and close the encrypted file

sudo umount  ../mp-encrypted/

sudo cryptsetup luksClose secretdata

Use:

#To access Data, open the file and mount it

sudo cryptsetup luksOpen encrypteddrive secretdata

sudo mount /dev/mapper/secretdata ../mp-encrypted/

#To close after use, unmount the partition and close the file

sudo umount  ../mp-encrypted/

sudo cryptsetup luksClose secretdata

Resize the secret file filesystem example: add 2 GB

#Add 2 GB to the file (8 x 256M)

dd if=/dev/zero of=encrypteddrive bs=256M count=8 oflag=append conv=notrunc

#Open the Encrypted device

sudo cryptsetup luksOpen encrypteddrive secretdata

#resize the encrypted partition

 sudo cryptsetup resize secretdata

 #check the EXT4 filesystem inside the encrypted file

 sudo e2fsck -f /dev/mapper/secretdata

 #Resize the EXT filesystem 

 sudo resize2fs /dev/mapper/secretdata