1 files changed, 78 insertions, 0 deletions
diff --git a/src/lib/modes/aead/gcm/ghash.h b/src/lib/modes/aead/gcm/ghash.h
new file mode 100644
index 000000000..7fcf7cfaa
--- /dev/null
+++ b/src/lib/modes/aead/gcm/ghash.h
@@ -0,0 +1,78 @@
+/*
+* (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_GCM_GHASH_H_
+#define BOTAN_GCM_GHASH_H_
+
+#include <botan/sym_algo.h>
+
+namespace Botan {
+
+/**
+* GCM's GHASH
+* This is not intended for general use, but is exposed to allow
+* shared code between GCM and GMAC
+*/
+class BOTAN_PUBLIC_API(2,0) GHASH final : public SymmetricAlgorithm
+   {
+   public:
+      void set_associated_data(const uint8_t ad[], size_t ad_len);
+
+      secure_vector<uint8_t> nonce_hash(const uint8_t nonce[], size_t len);
+
+      void start(const uint8_t nonce[], size_t len);
+
+      /*
+      * Assumes input len is multiple of 16
+      */
+      void update(const uint8_t in[], size_t len);
+
+      /*
+      * Incremental update of associated data
+      */
+      void update_associated_data(const uint8_t ad[], size_t len);
+
+      secure_vector<uint8_t> final();
+
+      Key_Length_Specification key_spec() const override
+         { return Key_Length_Specification(16); }
+
+      void clear() override;
+
+      void reset();
+
+      std::string name() const override { return "GHASH"; }
+
+      std::string provider() const;
+
+      void ghash_update(secure_vector<uint8_t>& x,
+                        const uint8_t input[], size_t input_len);
+
+      void add_final_block(secure_vector<uint8_t>& x,
+                           size_t ad_len, size_t pt_len);
+   private:
+      void key_schedule(const uint8_t key[], size_t key_len) override;
+
+      void gcm_multiply(secure_vector<uint8_t>& x,
+                        const uint8_t input[],
+                        size_t blocks);
+
+      static const size_t GCM_BS = 16;
+
+      secure_vector<uint8_t> m_H;
+      secure_vector<uint8_t> m_H_ad;
+      secure_vector<uint8_t> m_ghash;
+      secure_vector<uint8_t> m_nonce;
+      secure_vector<uint64_t> m_HM;
+      secure_vector<uint64_t> m_H_pow;
+      size_t m_ad_len = 0;
+      size_t m_text_len = 0;
+   };
+
+}
+
+#endif