2008-11-07 08:37:05

by Herbert Xu

[permalink] [raw]
Subject: [PATCH 5/10] crypto: hash - Add import/export interface

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 <[email protected]>
---

crypto/ahash.c | 14 ++++++++++++++
crypto/shash.c | 14 ++++++++++++++
include/crypto/hash.h | 21 +++++++++++++++++++++
include/crypto/internal/hash.h | 5 -----
include/linux/crypto.h | 1 +
5 files changed, 50 insertions(+), 5 deletions(-)

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 @@ 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)
{
diff --git a/crypto/shash.c b/crypto/shash.c
index 3f4c713..26aff3f 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -172,6 +172,20 @@ int crypto_shash_digest(struct shash_desc *desc, const u8 *data,
}
EXPORT_SYMBOL_GPL(crypto_shash_digest);

+int crypto_shash_import(struct shash_desc *desc, const u8 *in)
+{
+ struct crypto_shash *tfm = desc->tfm;
+ struct shash_alg *alg = crypto_shash_alg(tfm);
+
+ memcpy(shash_desc_ctx(desc), in, crypto_shash_descsize(tfm));
+
+ if (alg->reinit)
+ alg->reinit(desc);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_shash_import);
+
static int shash_async_setkey(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
{
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_desc {

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 @@ static inline unsigned int crypto_ahash_reqsize(struct crypto_ahash *tfm)
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 @@ static inline int crypto_ahash_digest(struct ahash_request *req)
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_setkey(struct crypto_shash *tfm, const u8 *key,
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);
diff --git a/include/crypto/internal/hash.h b/include/crypto/internal/hash.h
index 32d3a8e..92fbe73 100644
--- a/include/crypto/internal/hash.h
+++ b/include/crypto/internal/hash.h
@@ -66,11 +66,6 @@ static inline struct ahash_request *ahash_dequeue_request(
return ahash_request_cast(crypto_dequeue_request(queue));
}

-static inline void *ahash_request_ctx(struct ahash_request *req)
-{
- return req->__ctx;
-}