ecryptfs

kernel options

Make sure that ECRYPT_FS is enabled in the kernel. (gentoo)

 │ Symbol: ECRYPT_FS [=y]                                                                                                    │  
 │ Type  : tristate                                                                                                          │  
 │ Prompt: eCrypt filesystem layer support (EXPERIMENTAL)                                                                    │  
 │   Defined at fs/ecryptfs/Kconfig:1                                                                                        │  
 │   Depends on: MISC_FILESYSTEMS [=y] && EXPERIMENTAL [=y] && KEYS [=y] && CRYPTO [=y] && (ENCRYPTED_KEYS [=n] || ENCRYPTED │  
 │   Location:                                                                                                               │  
 │     -> File systems                                                                                                       │  
 │ (1)   -> Miscellaneous filesystems (MISC_FILESYSTEMS [=y])                                                                │  
 │   Selects: CRYPTO_ECB [=y] && CRYPTO_CBC [=y] && CRYPTO_MD5 [=y]

install (gentoo)

# emerge -av --quiet sys-fs/ecryptfs-utils