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