crypto: hash - Add import/export interface

It is often useful to save the partial state of a hash function
so that it can be used as a base for two or more computations.

The most prominent example is HMAC where all hashes start from
a base determined by the key.  Having an import/export interface
means that we only have to compute that base once rather than
for each message.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu
2008-11-02 21:38:11 +08:00
parent 3b2f6df082
commit dec8b78606
5 changed files with 50 additions and 5 deletions

View File

@@ -146,6 +146,20 @@ static int ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
return ahash->setkey(tfm, key, keylen);
}
int crypto_ahash_import(struct ahash_request *req, const u8 *in)
{
struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
struct ahash_alg *alg = crypto_ahash_alg(tfm);
memcpy(ahash_request_ctx(req), in, crypto_ahash_reqsize(tfm));
if (alg->reinit)
alg->reinit(req);
return 0;
}
EXPORT_SYMBOL_GPL(crypto_ahash_import);
static unsigned int crypto_ahash_ctxsize(struct crypto_alg *alg, u32 type,
u32 mask)
{