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crypto: doc - hash data structures 

The hash data structures needed to be filled in by cipher developers are
documented.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2014-11-12 05:26:03 +01:00 committed by Herbert Xu
parent aa1b6fbcbe
commit 5d8c723f61
1 changed files with 95 additions and 0 deletions
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95
include/crypto/hash.h
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@ -17,6 +17,28 @@
struct crypto_ahash;
/**
* DOC: Message Digest Algorithm Definitions
*
* These data structures define modular message digest algorithm
* implementations, managed via crypto_register_ahash(),
* crypto_register_shash(), crypto_unregister_ahash() and
* crypto_unregister_shash().
*/
/**
* struct hash_alg_common - define properties of message digest
* @digestsize: Size of the result of the transformation. A buffer of this size
* must be available to the @final and @finup calls, so they can
* store the resulting hash into it. For various predefined sizes,
* search include/crypto/ using
* git grep _DIGEST_SIZE include/crypto.
* @statesize: Size of the block for partial state of the transformation. A
* buffer of this size must be passed to the @export function as it
* will save the partial state of the transformation into it. On the
* other side, the @import function will load the state from a
* buffer of this size as well.
*/
struct hash_alg_common {
unsigned int digestsize;
unsigned int statesize;
@ -37,6 +59,62 @@ struct ahash_request {
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
/**
* struct ahash_alg - asynchronous message digest definition
* @init: Initialize the transformation context. Intended only to initialize the
* state of the HASH transformation at the begining. This shall fill in
* the internal structures used during the entire duration of the whole
* transformation. No data processing happens at this point.
* @update: Push a chunk of data into the driver for transformation. This
* function actually pushes blocks of data from upper layers into the
* driver, which then passes those to the hardware as seen fit. This
* function must not finalize the HASH transformation by calculating the
* final message digest as this only adds more data into the
* transformation. This function shall not modify the transformation
* context, as this function may be called in parallel with the same
* transformation object. Data processing can happen synchronously
* [SHASH] or asynchronously [AHASH] at this point.
* @final: Retrieve result from the driver. This function finalizes the
* transformation and retrieves the resulting hash from the driver and
* pushes it back to upper layers. No data processing happens at this
* point.
* @finup: Combination of @update and @final. This function is effectively a
* combination of @update and @final calls issued in sequence. As some
* hardware cannot do @update and @final separately, this callback was
* added to allow such hardware to be used at least by IPsec. Data
* processing can happen synchronously [SHASH] or asynchronously [AHASH]
* at this point.
* @digest: Combination of @init and @update and @final. This function
* effectively behaves as the entire chain of operations, @init,
* @update and @final issued in sequence. Just like @finup, this was
* added for hardware which cannot do even the @finup, but can only do
* the whole transformation in one run. Data processing can happen
* synchronously [SHASH] or asynchronously [AHASH] at this point.
* @setkey: Set optional key used by the hashing algorithm. Intended to push
* optional key used by the hashing algorithm from upper layers into
* the driver. This function can store the key in the transformation
* context or can outright program it into the hardware. In the former
* case, one must be careful to program the key into the hardware at
* appropriate time and one must be careful that .setkey() can be
* called multiple times during the existence of the transformation
* object. Not all hashing algorithms do implement this function as it
* is only needed for keyed message digests. SHAx/MDx/CRCx do NOT
* implement this function. HMAC(MDx)/HMAC(SHAx)/CMAC(AES) do implement
* this function. This function must be called before any other of the
* @init, @update, @final, @finup, @digest is called. No data
* processing happens at this point.
* @export: Export partial state of the transformation. This function dumps the
* entire state of the ongoing transformation into a provided block of
* data so it can be @import 'ed back later on. This is useful in case
* you want to save partial result of the transformation after
* processing certain amount of data and reload this partial result
* multiple times later on for multiple re-use. No data processing
* happens at this point.
* @import: Import partial state of the transformation. This function loads the
* entire state of the ongoing transformation from a provided block of
* data so the transformation can continue from this point onward. No
* data processing happens at this point.
*/
struct ahash_alg {
int (*init)(struct ahash_request *req);
int (*update)(struct ahash_request *req);
@ -63,6 +141,23 @@ struct shash_desc {
crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
struct shash_desc *shash = (struct shash_desc *)__##shash##_desc
/**
* struct shash_alg - synchronous message digest definition
* @init: see struct ahash_alg
* @update: see struct ahash_alg
* @final: see struct ahash_alg
* @finup: see struct ahash_alg
* @digest: see struct ahash_alg
* @export: see struct ahash_alg
* @import: see struct ahash_alg
* @setkey: see struct ahash_alg
* @digestsize: see struct ahash_alg
* @statesize: see struct ahash_alg
* @dedcsize: Size of the operational state for the message digest. This state
* size is the memory size that needs to be allocated for
* shash_desc.__ctx
* @base: internally used
*/
struct shash_alg {
int (*init)(struct shash_desc *desc);
int (*update)(struct shash_desc *desc, const u8 *data,