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>
diff --git a/crypto/ahash.c b/crypto/ahash.c
index 27128f2..7d4e33d 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -146,6 +146,20 @@
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)
{
