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/include/crypto/hash.h b/include/crypto/hash.h
index f9b51d4..cd16d6e 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -24,6 +24,7 @@
struct shash_alg {
int (*init)(struct shash_desc *desc);
+ int (*reinit)(struct shash_desc *desc);
int (*update)(struct shash_desc *desc, const u8 *data,
unsigned int len);
int (*final)(struct shash_desc *desc, u8 *out);
@@ -116,6 +117,11 @@
return crypto_ahash_crt(tfm)->reqsize;
}
+static inline void *ahash_request_ctx(struct ahash_request *req)
+{
+ return req->__ctx;
+}
+
static inline int crypto_ahash_setkey(struct crypto_ahash *tfm,
const u8 *key, unsigned int keylen)
{
@@ -130,6 +136,14 @@
return crt->digest(req);
}
+static inline void crypto_ahash_export(struct ahash_request *req, u8 *out)
+{
+ memcpy(out, ahash_request_ctx(req),
+ crypto_ahash_reqsize(crypto_ahash_reqtfm(req)));
+}
+
+int crypto_ahash_import(struct ahash_request *req, const u8 *in);
+
static inline int crypto_ahash_init(struct ahash_request *req)
{
struct ahash_tfm *crt = crypto_ahash_crt(crypto_ahash_reqtfm(req));
@@ -262,6 +276,13 @@
int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out);
+static inline void crypto_shash_export(struct shash_desc *desc, u8 *out)
+{
+ memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm));
+}
+
+int crypto_shash_import(struct shash_desc *desc, const u8 *in);
+
static inline int crypto_shash_init(struct shash_desc *desc)
{
return crypto_shash_alg(desc->tfm)->init(desc);