Rework ocb-aes128 interface, new struct ocb_aes128_encrypt_key.

3 files changed, 109 insertions, 52 deletions

diff --git a/ocb-aes128-meta.c b/ocb-aes128-meta.c
index 13095781..35f95f6e 100644
--- a/ocb-aes128-meta.c
+++ b/ocb-aes128-meta.c
@@ -39,11 +39,56 @@
 
 #define OCB_NONCE_SIZE 12
 
+struct ocb_aes128_ctx
+{
+  struct ocb_ctx ocb;
+  struct ocb_aes128_encrypt_key key;
+  struct aes128_ctx decrypt;
+};
+
+static void
+set_encrypt_key_wrapper (struct ocb_aes128_ctx *ctx, const uint8_t *key)
+{
+  ocb_aes128_set_encrypt_key(&ctx->key, key);
+}
+
+static void
+set_decrypt_key_wrapper (struct ocb_aes128_ctx *ctx, const uint8_t *key)
+{
+  ocb_aes128_set_decrypt_key(&ctx->key, &ctx->decrypt, key);
+}
+
+static void
+set_nonce_wrapper (struct ocb_aes128_ctx *ctx, const uint8_t *nonce)
+{
+  ocb_aes128_set_nonce (&ctx->ocb, &ctx->key,
+			OCB_DIGEST_SIZE, OCB_NONCE_SIZE, nonce);
+}
+
+static void
+update_wrapper (struct ocb_aes128_ctx *ctx, size_t length, const uint8_t *data)
+{
+  ocb_aes128_update (&ctx->ocb, &ctx->key, length, data);
+}
+
+static void
+encrypt_wrapper (struct ocb_aes128_ctx *ctx,
+		 size_t length, uint8_t *dst, const uint8_t *src)
+{
+  ocb_aes128_encrypt (&ctx->ocb, &ctx->key, length, dst, src);
+}
+
+static void
+decrypt_wrapper (struct ocb_aes128_ctx *ctx,
+		 size_t length, uint8_t *dst, const uint8_t *src)
+{
+  ocb_aes128_decrypt (&ctx->ocb, &ctx->key, &ctx->decrypt, length, dst, src);
+}
+
 static void
-ocb_aes128_set_nonce12 (struct ocb_aes128_ctx *ctx,
-		      const uint8_t *nonce)
+digest_wrapper (struct ocb_aes128_ctx *ctx, size_t length, uint8_t *digest)
 {
-  ocb_aes128_set_nonce (ctx, OCB_NONCE_SIZE, nonce);
+  ocb_aes128_digest (&ctx->ocb, &ctx->key, length, digest);
 }
 
 const struct nettle_aead
@@ -51,11 +96,11 @@ nettle_ocb_aes128 =
   { "ocb_aes128", sizeof(struct ocb_aes128_ctx),
     OCB_BLOCK_SIZE, AES128_KEY_SIZE,
     OCB_NONCE_SIZE, OCB_DIGEST_SIZE,
-    (nettle_set_key_func *) ocb_aes128_set_key,
-    (nettle_set_key_func *) ocb_aes128_set_key,
-    (nettle_set_key_func *) ocb_aes128_set_nonce12,
-    (nettle_hash_update_func *) ocb_aes128_update,
-    (nettle_crypt_func *) ocb_aes128_encrypt,
-    (nettle_crypt_func *) ocb_aes128_decrypt,
-    (nettle_hash_digest_func *) ocb_aes128_digest
+    (nettle_set_key_func *) set_encrypt_key_wrapper,
+    (nettle_set_key_func *) set_decrypt_key_wrapper,
+    (nettle_set_key_func *) set_nonce_wrapper,
+    (nettle_hash_update_func *) update_wrapper,
+    (nettle_crypt_func *) encrypt_wrapper,
+    (nettle_crypt_func *) decrypt_wrapper,
+    (nettle_hash_digest_func *) digest_wrapper
   };
diff --git a/ocb-aes128.c b/ocb-aes128.c
index 6c1b70dc..c72ada2c 100644
--- a/ocb-aes128.c
+++ b/ocb-aes128.c
@@ -36,79 +36,83 @@
 #include "ocb.h"
 
 void
-ocb_aes128_set_key (struct ocb_aes128_ctx *ctx, const uint8_t *key)
+ocb_aes128_set_encrypt_key (struct ocb_aes128_encrypt_key *ocb_key, const uint8_t *key)
 {
-  aes128_set_encrypt_key (&ctx->encrypt, key);
-  aes128_invert_key (&ctx->decrypt, &ctx->encrypt);
-  ocb_set_key (&ctx->key, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt);
+  aes128_set_encrypt_key (&ocb_key->encrypt, key);
+  ocb_set_key (&ocb_key->ocb, &ocb_key->encrypt, (nettle_cipher_func *) aes128_encrypt);
 }
 
 void
-ocb_aes128_set_nonce (struct ocb_aes128_ctx *ctx,
-		      size_t nonce_length, const uint8_t *nonce)
+ocb_aes128_set_decrypt_key (struct ocb_aes128_encrypt_key *ocb_key, struct aes128_ctx *decrypt,
+			    const uint8_t *key)
 {
-  ocb_set_nonce (&ctx->ocb, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt,
-		 OCB_DIGEST_SIZE, nonce_length, nonce);
+  ocb_aes128_set_encrypt_key (ocb_key, key);
+  aes128_invert_key (decrypt, &ocb_key->encrypt);
 }
 
 void
-ocb_aes128_update (struct ocb_aes128_ctx *ctx,
+ocb_aes128_set_nonce (struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		      size_t tag_length, size_t nonce_length, const uint8_t *nonce)
+{
+  ocb_set_nonce (ctx, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
+		 tag_length, nonce_length, nonce);
+}
+
+void
+ocb_aes128_update (struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
 		   size_t length, const uint8_t *data)
 {
-  ocb_update (&ctx->ocb, &ctx->key, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt,
+  ocb_update (ctx, &key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
 	      length, data);
 }
 
 void
-ocb_aes128_encrypt(struct ocb_aes128_ctx *ctx,
+ocb_aes128_encrypt(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
 		   size_t length, uint8_t *dst, const uint8_t *src)
 {
-  ocb_encrypt (&ctx->ocb, &ctx->key, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt,
+  ocb_encrypt (ctx, &key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
 	       length, dst, src);
 }
 
 void
-ocb_aes128_decrypt(struct ocb_aes128_ctx *ctx,
+ocb_aes128_decrypt(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		   const struct aes128_ctx *decrypt,
 		   size_t length, uint8_t *dst, const uint8_t *src)
 {
-  ocb_decrypt (&ctx->ocb, &ctx->key, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt,
-	       &ctx->decrypt, (nettle_cipher_func *) aes128_decrypt,
+  ocb_decrypt (ctx, &key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
+	       decrypt, (nettle_cipher_func *) aes128_decrypt,
 	       length, dst, src);
 }
 
 void
-ocb_aes128_digest(struct ocb_aes128_ctx *ctx, size_t length, uint8_t *digest)
+ocb_aes128_digest(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		  size_t length, uint8_t *digest)
 {
-  ocb_digest (&ctx->ocb, &ctx->key, &ctx->encrypt, (nettle_cipher_func *) aes128_encrypt,
+  ocb_digest (ctx, &key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
 	      length, digest);
 }
 
 void
-ocb_aes128_encrypt_message (const struct aes128_ctx *cipher,
+ocb_aes128_encrypt_message (const struct ocb_aes128_encrypt_key *key,
 			    size_t nlength, const uint8_t *nonce,
 			    size_t alength, const uint8_t *adata,
 			    size_t tlength,
 			    size_t clength, uint8_t *dst, const uint8_t *src)
 {
-  struct ocb_key key;
-  ocb_set_key (&key, cipher, (nettle_cipher_func *) aes128_encrypt);
-  ocb_encrypt_message (&key, cipher, (nettle_cipher_func *) aes128_encrypt,
+  ocb_encrypt_message (&key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
 		       nlength, nonce, alength, adata, tlength, clength, dst, src);
 }
 
 int
-ocb_aes128_decrypt_message (const struct aes128_ctx *cipher,
+ocb_aes128_decrypt_message (const struct ocb_aes128_encrypt_key *key,
+			    const struct aes128_ctx *decrypt,
 			    size_t nlength, const uint8_t *nonce,
 			    size_t alength, const uint8_t *adata,
 			    size_t tlength,
 			    size_t mlength, uint8_t *dst, const uint8_t *src)
 {
-  struct ocb_key key;
-  struct aes128_ctx decrypt_ctx;
-  aes128_invert_key (&decrypt_ctx, cipher);
-  ocb_set_key (&key, cipher, (nettle_cipher_func *) aes128_encrypt);
-  return ocb_decrypt_message (&key, cipher, (nettle_cipher_func *) aes128_encrypt,
-			      &decrypt_ctx, (nettle_cipher_func *) aes128_decrypt,
+  return ocb_decrypt_message (&key->ocb, &key->encrypt, (nettle_cipher_func *) aes128_encrypt,
+			      &decrypt, (nettle_cipher_func *) aes128_decrypt,
 			      nlength, nonce, alength, adata,
 			      tlength, mlength, dst, src);
 }
diff --git a/ocb.h b/ocb.h
index a5bc93ec..663368bd 100644
--- a/ocb.h
+++ b/ocb.h
@@ -50,7 +50,8 @@ extern "C" {
 #define ocb_digest nettle_ocb_digest
 #define ocb_encrypt_message nettle_ocb_encrypt_message
 #define ocb_decrypt_message nettle_ocb_decrypt_message
-#define ocb_aes128_set_key nettle_ocb_aes128_set_key
+#define ocb_aes128_set_encrypt_key nettle_ocb_aes128_set_encrypt_key
+#define ocb_aes128_set_decrypt_key nettle_ocb_aes128_set_decrypt_key
 #define ocb_aes128_set_nonce nettle_ocb_aes128_set_nonce
 #define ocb_aes128_update nettle_ocb_aes128_update
 #define ocb_aes128_encrypt nettle_ocb_aes128_encrypt
@@ -140,45 +141,52 @@ ocb_decrypt_message (const struct ocb_key *ocb_key,
 		     size_t mlength, uint8_t *dst, const uint8_t *src);
 
 /* OCB-AES */
-struct ocb_aes128_ctx
+/* This struct represents an expanded key for ocb-aes encryption. For
+   decryption, a separate decryption context is needed as well. */
+struct ocb_aes128_encrypt_key
 {
-  struct ocb_key key;
-  struct ocb_ctx ocb;
+  struct ocb_key ocb;
   struct aes128_ctx encrypt;
-  struct aes128_ctx decrypt;
 };
 
 void
-ocb_aes128_set_key (struct ocb_aes128_ctx *ctx, const uint8_t *key);
+ocb_aes128_set_encrypt_key (struct ocb_aes128_encrypt_key *ocb, const uint8_t *key);
 
 void
-ocb_aes128_set_nonce (struct ocb_aes128_ctx *ctx,
-		      size_t nonce_length, const uint8_t *nonce);
+ocb_aes128_set_decrypt_key (struct ocb_aes128_encrypt_key *ocb, struct aes128_ctx *decrypt,
+			    const uint8_t *key);
 
 void
-ocb_aes128_update (struct ocb_aes128_ctx *ctx,
+ocb_aes128_set_nonce (struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		      size_t tag_length, size_t nonce_length, const uint8_t *nonce);
+
+void
+ocb_aes128_update (struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
 		   size_t length, const uint8_t *data);
 
 void
-ocb_aes128_encrypt(struct ocb_aes128_ctx *ctx,
+ocb_aes128_encrypt(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
 		   size_t length, uint8_t *dst, const uint8_t *src);
 
 void
-ocb_aes128_decrypt(struct ocb_aes128_ctx *ctx,
+ocb_aes128_decrypt(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		   const struct aes128_ctx *decrypt,
 		   size_t length, uint8_t *dst, const uint8_t *src);
 
 void
-ocb_aes128_digest(struct ocb_aes128_ctx *ctx, size_t length, uint8_t *digest);
+ocb_aes128_digest(struct ocb_ctx *ctx, const struct ocb_aes128_encrypt_key *key,
+		  size_t length, uint8_t *digest);
 
 void
-ocb_aes128_encrypt_message (const struct aes128_ctx *cipher,
+ocb_aes128_encrypt_message (const struct ocb_aes128_encrypt_key *key,
 			    size_t nlength, const uint8_t *nonce,
 			    size_t alength, const uint8_t *adata,
 			    size_t tlength,
 			    size_t clength, uint8_t *dst, const uint8_t *src);
 
 int
-ocb_aes128_decrypt_message (const struct aes128_ctx *cipher,
+ocb_aes128_decrypt_message (const struct ocb_aes128_encrypt_key *key,
+			    const struct aes128_ctx *decrypt,
 			    size_t nlength, const uint8_t *nonce,
 			    size_t alength, const uint8_t *adata,
 			    size_t tlength,