Commit e455de31 authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: add comments that describe the HKDF info strings 

Each HKDF context byte is associated with a specific format of the
remaining part of the application-specific info string.  Add comments so
that it's easier to keep track of what these all are.

Link: https://lore.kernel.org/r/20200708215529.146890-1-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 4f74d15f

fs/crypto/fscrypt_private.h

+7 −7
Original line number Diff line number Diff line
@@ -312,13 +312,13 @@ int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, 
 * outputs are unique and cryptographically isolated, i.e. knowledge of one

 * output doesn't reveal another.

 */

#define HKDF_CONTEXT_KEY_IDENTIFIER	1

#define HKDF_CONTEXT_PER_FILE_ENC_KEY	2

#define HKDF_CONTEXT_DIRECT_KEY		3

#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4

#define HKDF_CONTEXT_DIRHASH_KEY	5

#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY	6

#define HKDF_CONTEXT_INODE_HASH_KEY	7

#define HKDF_CONTEXT_KEY_IDENTIFIER	1 /* info=<empty>		*/

#define HKDF_CONTEXT_PER_FILE_ENC_KEY	2 /* info=file_nonce		*/

#define HKDF_CONTEXT_DIRECT_KEY		3 /* info=mode_num		*/

#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4 /* info=mode_num||fs_uuid	*/

#define HKDF_CONTEXT_DIRHASH_KEY	5 /* info=file_nonce		*/

#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY	6 /* info=mode_num||fs_uuid	*/

#define HKDF_CONTEXT_INODE_HASH_KEY	7 /* info=<empty>		*/



int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,

			const u8 *info, unsigned int infolen,

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