Add MAC::start_msg, update GMAC

GMAC needs a per-message nonce specified with `start`, and other
MACs are capable of using nonces (Skein-MAC, for instance) so move
this API up to MAC class.

Change GMAC::clone to clone the owned cipher.

2 files changed, 4 insertions, 14 deletions

diff --git a/src/lib/mac/gmac/gmac.cpp b/src/lib/mac/gmac/gmac.cpp
index 946e22cf0..4461cf370 100644
--- a/src/lib/mac/gmac/gmac.cpp
+++ b/src/lib/mac/gmac/gmac.cpp
@@ -64,17 +64,7 @@ void GMAC::key_schedule(const byte key[], size_t size)
    m_cipher->encrypt(m_H_ad.data(), m_H.data());
    }
 
-void GMAC::start(const std::vector<byte>& nonce)
-   {
-   start(nonce.data(), nonce.size());
-   }
-
-void GMAC::start(const secure_vector<byte>& nonce)
-   {
-   start(nonce.data(), nonce.size());
-   }
-
-void GMAC::start(const byte nonce[], size_t nonce_len)
+void GMAC::start_msg(const byte nonce[], size_t nonce_len)
    {
    secure_vector<byte> y0(GCM_BS);
 
@@ -118,6 +108,6 @@ void GMAC::final_result(byte mac[])
 
 MessageAuthenticationCode* GMAC::clone() const
    {
-   return new GMAC(BlockCipher::create(m_cipher->name()).release());
+   return new GMAC(m_cipher->clone());
    }
 }
diff --git a/src/lib/mac/gmac/gmac.h b/src/lib/mac/gmac/gmac.h
index b651c2e11..b05c5451f 100644
--- a/src/lib/mac/gmac/gmac.h
+++ b/src/lib/mac/gmac/gmac.h
@@ -53,7 +53,7 @@ class BOTAN_DLL GMAC : public MessageAuthenticationCode,
       */
       void start(const std::vector<byte>& nonce);
 
-      Key_Length_Specification key_spec() const
+      Key_Length_Specification key_spec() const override
          {
          return m_cipher->key_spec();
          }
@@ -71,7 +71,7 @@ class BOTAN_DLL GMAC : public MessageAuthenticationCode,
    private:
       void add_data(const byte[], size_t) override;
       void final_result(byte[]) override;
-      void start_msg(const byte nonce[], size_t nonce_len);
+      void start_msg(const byte nonce[], size_t nonce_len) override;
       void key_schedule(const byte key[], size_t size) override;
 
       static const size_t GCM_BS = 16;