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Diffstat (limited to 'Documentation/filesystems/fscrypt.rst')
| -rw-r--r-- | Documentation/filesystems/fscrypt.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 380a1be9550e..c45f5bcc13e1 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -302,6 +302,16 @@ For master keys used for v2 encryption policies, a unique 16-byte "key identifier" is also derived using the KDF. This value is stored in the clear, since it is needed to reliably identify the key itself. +Dirhash keys +------------ + +For directories that are indexed using a secret-keyed dirhash over the +plaintext filenames, the KDF is also used to derive a 128-bit +SipHash-2-4 key per directory in order to hash filenames. This works +just like deriving a per-file encryption key, except that a different +KDF context is used. Currently, only casefolded ("case-insensitive") +encrypted directories use this style of hashing. + Encryption modes and usage ========================== |