Add T::provider() to allow user to inquire about implementation used

For block ciphers, stream ciphers, hashes, MACs, and cipher modes.
Cipher_Mode already had it, with a slightly different usage.

3 files changed, 19 insertions, 8 deletions

diff --git a/src/lib/modes/aead/gcm/gcm.cpp b/src/lib/modes/aead/gcm/gcm.cpp
index e23551cb4..590c0d0ce 100644
--- a/src/lib/modes/aead/gcm/gcm.cpp
+++ b/src/lib/modes/aead/gcm/gcm.cpp
@@ -185,6 +185,16 @@ std::string GCM_Mode::name() const
    return (m_cipher_name + "/GCM");
    }
 
+const char* GCM_Mode::provider() const
+   {
+#if defined(BOTAN_HAS_GCM_CLMUL)
+   if(CPUID::has_clmul())
+      return "clmul";
+#endif
+
+   return "base";
+   }
+
 size_t GCM_Mode::update_granularity() const
    {
    return m_BS;
diff --git a/src/lib/modes/aead/gcm/gcm.h b/src/lib/modes/aead/gcm/gcm.h
index ba0d6cad8..f0176f36a 100644
--- a/src/lib/modes/aead/gcm/gcm.h
+++ b/src/lib/modes/aead/gcm/gcm.h
@@ -36,6 +36,8 @@ class BOTAN_DLL GCM_Mode : public AEAD_Mode
       size_t tag_size() const override { return m_tag_size; }
 
       void clear() override;
+
+      const char* provider() const override;
    protected:
       GCM_Mode(BlockCipher* cipher, size_t tag_size);
 
diff --git a/src/lib/modes/cipher_mode.h b/src/lib/modes/cipher_mode.h
index 73a5f7d96..fa4c0aa8d 100644
--- a/src/lib/modes/cipher_mode.h
+++ b/src/lib/modes/cipher_mode.h
@@ -113,14 +113,6 @@ class BOTAN_DLL Cipher_Mode
       */
       virtual bool valid_nonce_length(size_t nonce_len) const = 0;
 
-      /**
-      * Return some short name describing the provider of this tranformation.
-      * Useful in cases where multiple implementations are available (eg,
-      * different implementations of AES). Default "core" is used for the
-      * 'standard' implementation included in the library.
-      */
-      virtual std::string provider() const { return "core"; }
-
       virtual std::string name() const = 0;
 
       virtual void clear() = 0;
@@ -174,6 +166,13 @@ class BOTAN_DLL Cipher_Mode
          key_schedule(key, length);
          }
 
+      /**
+      * @return provider information about this implementation. Default is "base",
+      * might also return "sse2", "avx2", "openssl", or some other arbitrary string.
+      * The return value is guaranteed to point to a string literal constant.
+      */
+      virtual const char* provider() const { return "base"; }
+
    private:
       virtual void key_schedule(const byte key[], size_t length) = 0;
    };