Cipher_Mode and AEAD_Mode improvements

See PR #552

- Add Cipher_Mode::reset() which resets just the message specific state and allows encrypting again under the existing key
- In Cipher_Mode::clear() (at some planes) use cipher->clear() instead of resetting the pointer which would make the cipher object unusable
- EAX_Decryption::output_length() bugfix?! Now its possible to decrypt an empty ciphertext (just a tag)
- Bugfix for GCM_Decryption::finish()
- set tag length in GCM_Mode::name()
- Cipher_Mode tests: add tests for reset()and process()
- AEAD_Mode tests: add tests for reset(), clear(), update() and process()

26 files changed, 491 insertions, 64 deletions

diff --git a/src/lib/modes/aead/ccm/ccm.cpp b/src/lib/modes/aead/ccm/ccm.cpp
index 81b9f4943..de639f23a 100644
--- a/src/lib/modes/aead/ccm/ccm.cpp
+++ b/src/lib/modes/aead/ccm/ccm.cpp
@@ -1,6 +1,7 @@
 /*
 * CCM Mode Encryption
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -33,7 +34,13 @@ CCM_Mode::CCM_Mode(BlockCipher* cipher, size_t tag_size, size_t L) :
 
 void CCM_Mode::clear()
    {
-   m_cipher.reset();
+   m_cipher->clear();
+   reset();
+   }
+
+void CCM_Mode::reset()
+   {
+   m_nonce.clear();
    m_msg_buf.clear();
    m_ad_buf.clear();
    }
diff --git a/src/lib/modes/aead/ccm/ccm.h b/src/lib/modes/aead/ccm/ccm.h
index 7484b500a..2a17595e7 100644
--- a/src/lib/modes/aead/ccm/ccm.h
+++ b/src/lib/modes/aead/ccm/ccm.h
@@ -1,6 +1,7 @@
 /*
 * CCM Mode
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -38,6 +39,8 @@ class BOTAN_DLL CCM_Mode : public AEAD_Mode
 
       void clear() override;
 
+      void reset() override;
+
       size_t tag_size() const override { return m_tag_size; }
 
    protected:
diff --git a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp
index d2f16c225..197d6f921 100644
--- a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp
+++ b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp
@@ -1,6 +1,7 @@
 /*
 * ChaCha20Poly1305 AEAD
 * (C) 2014,2016 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -26,8 +27,14 @@ void ChaCha20Poly1305_Mode::clear()
    {
    m_chacha->clear();
    m_poly1305->clear();
+   reset();
+   }
+
+void ChaCha20Poly1305_Mode::reset()
+   {
    m_ad.clear();
    m_ctext_len = 0;
+   m_nonce_len = 0;
    }
 
 void ChaCha20Poly1305_Mode::key_schedule(const byte key[], size_t length)
diff --git a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
index 553508854..f58bd48ac 100644
--- a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
+++ b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
@@ -1,6 +1,7 @@
 /*
 * ChaCha20Poly1305 AEAD
 * (C) 2014 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -37,6 +38,9 @@ class BOTAN_DLL ChaCha20Poly1305_Mode : public AEAD_Mode
       size_t tag_size() const override { return 16; }
 
       void clear() override;
+
+      void reset() override;
+
    protected:
       std::unique_ptr<StreamCipher> m_chacha;
       std::unique_ptr<MessageAuthenticationCode> m_poly1305;
diff --git a/src/lib/modes/aead/eax/eax.cpp b/src/lib/modes/aead/eax/eax.cpp
index c76f15b48..ba52efcfd 100644
--- a/src/lib/modes/aead/eax/eax.cpp
+++ b/src/lib/modes/aead/eax/eax.cpp
@@ -1,6 +1,7 @@
 /*
 * EAX Mode Encryption
 * (C) 1999-2007 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -22,7 +23,9 @@ secure_vector<byte> eax_prf(byte tag, size_t block_size,
                            const byte in[], size_t length)
    {
    for(size_t i = 0; i != block_size - 1; ++i)
+      {
       mac.update(0);
+      }
    mac.update(tag);
    mac.update(in, length);
    return mac.final();
@@ -45,11 +48,16 @@ EAX_Mode::EAX_Mode(BlockCipher* cipher, size_t tag_size) :
 
 void EAX_Mode::clear()
    {
-   m_cipher.reset();
-   m_ctr.reset();
-   m_cmac.reset();
-   zeroise(m_ad_mac);
-   zeroise(m_nonce_mac);
+   m_cipher->clear();
+   m_ctr->clear();
+   m_cmac->clear();
+   reset();
+   }
+
+void EAX_Mode::reset()
+   {
+   m_ad_mac.clear();
+   m_nonce_mac.clear();
    }
 
 std::string EAX_Mode::name() const
@@ -78,8 +86,6 @@ void EAX_Mode::key_schedule(const byte key[], size_t length)
    */
    m_ctr->set_key(key, length);
    m_cmac->set_key(key, length);
-
-   m_ad_mac = eax_prf(1, block_size(), *m_cmac, nullptr, 0);
    }
 
 /*
@@ -117,6 +123,12 @@ void EAX_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
 
    secure_vector<byte> data_mac = m_cmac->final();
    xor_buf(data_mac, m_nonce_mac, data_mac.size());
+
+   if(m_ad_mac.empty())
+      {
+      m_ad_mac = eax_prf(1, block_size(), *m_cmac, nullptr, 0);
+      }
+
    xor_buf(data_mac, m_ad_mac, data_mac.size());
 
    buffer += std::make_pair(data_mac.data(), tag_size());
@@ -149,6 +161,12 @@ void EAX_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
 
    secure_vector<byte> mac = m_cmac->final();
    mac ^= m_nonce_mac;
+
+   if(m_ad_mac.empty())
+      {
+      m_ad_mac = eax_prf(1, block_size(), *m_cmac, nullptr, 0);
+      }
+
    mac ^= m_ad_mac;
 
    if(!same_mem(mac.data(), included_tag, tag_size()))
diff --git a/src/lib/modes/aead/eax/eax.h b/src/lib/modes/aead/eax/eax.h
index 0dedefe07..c0b6bcf42 100644
--- a/src/lib/modes/aead/eax/eax.h
+++ b/src/lib/modes/aead/eax/eax.h
@@ -1,6 +1,7 @@
 /*
 * EAX Mode
 * (C) 1999-2007,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -35,6 +36,9 @@ class BOTAN_DLL EAX_Mode : public AEAD_Mode
       size_t tag_size() const override { return m_tag_size; }
 
       void clear() override;
+
+      void reset() override;
+
    protected:
       /**
       * @param cipher the cipher to use
@@ -97,7 +101,7 @@ class BOTAN_DLL EAX_Decryption final : public EAX_Mode
 
       size_t output_length(size_t input_length) const override
          {
-         BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
+         BOTAN_ASSERT(input_length >= tag_size(), "Sufficient input");
          return input_length - tag_size();
          }
 
diff --git a/src/lib/modes/aead/gcm/gcm.cpp b/src/lib/modes/aead/gcm/gcm.cpp
index a73e5ee5b..e0bc59a8d 100644
--- a/src/lib/modes/aead/gcm/gcm.cpp
+++ b/src/lib/modes/aead/gcm/gcm.cpp
@@ -1,6 +1,7 @@
 /*
 * GCM Mode Encryption
 * (C) 2013,2015 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -150,8 +151,14 @@ secure_vector<byte> GHASH::nonce_hash(const byte nonce[], size_t nonce_len)
 void GHASH::clear()
    {
    zeroise(m_H);
+   reset();
+   }
+
+void GHASH::reset()
+   {
    zeroise(m_H_ad);
    m_ghash.clear();
+   m_nonce.clear();
    m_text_len = m_ad_len = 0;
    }
 
@@ -177,11 +184,17 @@ void GCM_Mode::clear()
    {
    m_ctr->clear();
    m_ghash->clear();
+   reset();
+   }
+
+void GCM_Mode::reset()
+   {
+   m_ghash->reset();
    }
 
 std::string GCM_Mode::name() const
    {
-   return (m_cipher_name + "/GCM");
+   return (m_cipher_name + "/GCM(" + std::to_string(tag_size()) + ")");
    }
 
 std::string GCM_Mode::provider() const
@@ -294,7 +307,7 @@ void GCM_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
 
    auto mac = m_ghash->final();
 
-   const byte* included_tag = &buffer[remaining];
+   const byte* included_tag = &buffer[remaining+offset];
 
    if(!same_mem(mac.data(), included_tag, tag_size()))
       throw Integrity_Failure("GCM tag check failed");
diff --git a/src/lib/modes/aead/gcm/gcm.h b/src/lib/modes/aead/gcm/gcm.h
index 6468cbd9c..463e69a3b 100644
--- a/src/lib/modes/aead/gcm/gcm.h
+++ b/src/lib/modes/aead/gcm/gcm.h
@@ -1,6 +1,7 @@
 /*
 * GCM Mode
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -37,6 +38,8 @@ class BOTAN_DLL GCM_Mode : public AEAD_Mode
 
       void clear() override;
 
+      void reset() override;
+
       std::string provider() const override;
    protected:
       GCM_Mode(BlockCipher* cipher, size_t tag_size);
@@ -128,6 +131,8 @@ class BOTAN_DLL GHASH : public SymmetricAlgorithm
 
       void clear() override;
 
+      void reset();
+
       std::string name() const override { return "GHASH"; }
    protected:
       void ghash_update(secure_vector<byte>& x,
diff --git a/src/lib/modes/aead/ocb/ocb.cpp b/src/lib/modes/aead/ocb/ocb.cpp
index 0ce2b6f00..c530dda5d 100644
--- a/src/lib/modes/aead/ocb/ocb.cpp
+++ b/src/lib/modes/aead/ocb/ocb.cpp
@@ -1,6 +1,7 @@
 /*
 * OCB Mode
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -129,12 +130,19 @@ OCB_Mode::~OCB_Mode() { /* for unique_ptr destructor */ }
 
 void OCB_Mode::clear()
    {
-   m_cipher.reset();
-   m_L.reset();
+   m_cipher->clear();
+   m_L.reset(); // add clear here?
+   reset();
+   }
 
+void OCB_Mode::reset()
+   {
+   m_block_index = 0;
    zeroise(m_ad_hash);
    zeroise(m_offset);
    zeroise(m_checksum);
+   m_last_nonce.clear();
+   m_stretch.clear();
    }
 
 bool OCB_Mode::valid_nonce_length(size_t length) const
diff --git a/src/lib/modes/aead/ocb/ocb.h b/src/lib/modes/aead/ocb/ocb.h
index 4daa7a81b..ce9d29f1b 100644
--- a/src/lib/modes/aead/ocb/ocb.h
+++ b/src/lib/modes/aead/ocb/ocb.h
@@ -1,6 +1,7 @@
 /*
 * OCB Mode
 * (C) 2013,2014 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -41,6 +42,8 @@ class BOTAN_DLL OCB_Mode : public AEAD_Mode
 
       void clear() override;
 
+      void reset() override;
+
       ~OCB_Mode();
    protected:
       /**
diff --git a/src/lib/modes/aead/siv/siv.cpp b/src/lib/modes/aead/siv/siv.cpp
index ce20f3ada..373a2627c 100644
--- a/src/lib/modes/aead/siv/siv.cpp
+++ b/src/lib/modes/aead/siv/siv.cpp
@@ -1,6 +1,7 @@
 /*
 * SIV Mode Encryption
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -23,7 +24,13 @@ SIV_Mode::SIV_Mode(BlockCipher* cipher) :
 
 void SIV_Mode::clear()
    {
-   m_ctr.reset();
+   m_ctr->clear();
+   m_cmac->clear();
+   reset();
+   }
+
+void SIV_Mode::reset()
+   {
    m_nonce.clear();
    m_msg_buf.clear();
    m_ad_macs.clear();
diff --git a/src/lib/modes/aead/siv/siv.h b/src/lib/modes/aead/siv/siv.h
index ca3e7df37..71990ef96 100644
--- a/src/lib/modes/aead/siv/siv.h
+++ b/src/lib/modes/aead/siv/siv.h
@@ -1,6 +1,7 @@
 /*
 * SIV Mode
 * (C) 2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -46,6 +47,8 @@ class BOTAN_DLL SIV_Mode : public AEAD_Mode
 
       void clear() override;
 
+      void reset() override;
+
       size_t tag_size() const override { return 16; }
 
    protected:
diff --git a/src/lib/modes/cbc/cbc.cpp b/src/lib/modes/cbc/cbc.cpp
index 7e1fe4d0f..592ff95e9 100644
--- a/src/lib/modes/cbc/cbc.cpp
+++ b/src/lib/modes/cbc/cbc.cpp
@@ -1,6 +1,7 @@
 /*
 * CBC Mode
 * (C) 1999-2007,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -25,7 +26,12 @@ CBC_Mode::CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding) :
 void CBC_Mode::clear()
    {
    m_cipher->clear();
-   m_state.clear();
+   reset();
+   }
+
+void CBC_Mode::reset()
+   {
+   zeroise(m_state);
    }
 
 std::string CBC_Mode::name() const
@@ -239,6 +245,12 @@ void CBC_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
    buffer.resize(buffer.size() - pad_bytes); // remove padding
    }
 
+void CBC_Decryption::reset()
+   {
+   zeroise(state());
+   zeroise(m_tempbuf);
+   }
+
 bool CTS_Decryption::valid_nonce_length(size_t n) const
    {
    return (n == cipher().block_size());
diff --git a/src/lib/modes/cbc/cbc.h b/src/lib/modes/cbc/cbc.h
index c6b6e4e4b..1b7cbd323 100644
--- a/src/lib/modes/cbc/cbc.h
+++ b/src/lib/modes/cbc/cbc.h
@@ -1,6 +1,7 @@
 /*
 * CBC mode
 * (C) 1999-2007,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -31,6 +32,9 @@ class BOTAN_DLL CBC_Mode : public Cipher_Mode
       bool valid_nonce_length(size_t n) const override;
 
       void clear() override;
+
+      void reset() override;
+
    protected:
       CBC_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding);
 
@@ -118,6 +122,9 @@ class BOTAN_DLL CBC_Decryption : public CBC_Mode
       size_t output_length(size_t input_length) const override;
 
       size_t minimum_final_size() const override;
+
+      void reset() override;
+
    private:
       secure_vector<byte> m_tempbuf;
    };
diff --git a/src/lib/modes/cfb/cfb.cpp b/src/lib/modes/cfb/cfb.cpp
index 793bfaf46..2d1477e27 100644
--- a/src/lib/modes/cfb/cfb.cpp
+++ b/src/lib/modes/cfb/cfb.cpp
@@ -1,6 +1,7 @@
 /*
 * CFB Mode
 * (C) 1999-2007,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -22,7 +23,13 @@ CFB_Mode::CFB_Mode(BlockCipher* cipher, size_t feedback_bits) :
 void CFB_Mode::clear()
    {
    m_cipher->clear();
+   reset();
+   }
+
+void CFB_Mode::reset()
+   {
    m_shift_register.clear();
+   m_keystream_buf.clear();
    }
 
 std::string CFB_Mode::name() const
diff --git a/src/lib/modes/cfb/cfb.h b/src/lib/modes/cfb/cfb.h
index 318bdab64..18611f3f2 100644
--- a/src/lib/modes/cfb/cfb.h
+++ b/src/lib/modes/cfb/cfb.h
@@ -1,6 +1,7 @@
 /*
 * CFB mode
 * (C) 1999-2007,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -34,6 +35,8 @@ class BOTAN_DLL CFB_Mode : public Cipher_Mode
       bool valid_nonce_length(size_t n) const override;
 
       void clear() override;
+
+      void reset() override;
    protected:
       CFB_Mode(BlockCipher* cipher, size_t feedback_bits);
 
diff --git a/src/lib/modes/cipher_mode.h b/src/lib/modes/cipher_mode.h
index 7c0f8fc57..8bf58f10a 100644
--- a/src/lib/modes/cipher_mode.h
+++ b/src/lib/modes/cipher_mode.h
@@ -65,7 +65,7 @@ class BOTAN_DLL Cipher_Mode
       *
       * Processes msg in place and returns bytes written. Normally
       * this will be either msg_len (indicating the entire message was
-      * processes) or for certain AEAD modes zero (indicating that the
+      * processed) or for certain AEAD modes zero (indicating that the
       * mode requires the entire message be processed in one pass).
       *
       * @param msg the message to be processed
@@ -127,9 +127,18 @@ class BOTAN_DLL Cipher_Mode
 
       virtual std::string name() const = 0;
 
+      /**
+      * Zeroise all state
+      * See also reset_msg()
+      */
       virtual void clear() = 0;
 
       /**
+      * Resets just the message specific state and allows encrypting again under the existing key
+      */
+      virtual void reset() = 0;
+
+      /**
       * @return true iff this mode provides authentication as well as
       * confidentiality.
       */
diff --git a/src/lib/modes/ecb/ecb.cpp b/src/lib/modes/ecb/ecb.cpp
index b39682fdf..78dff5ffa 100644
--- a/src/lib/modes/ecb/ecb.cpp
+++ b/src/lib/modes/ecb/ecb.cpp
@@ -1,6 +1,7 @@
 /*
 * ECB Mode
 * (C) 1999-2009,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -25,6 +26,12 @@ void ECB_Mode::clear()
    m_cipher->clear();
    }
 
+void ECB_Mode::reset()
+   {
+   // no msg state here
+   return;
+   }
+
 std::string ECB_Mode::name() const
    {
    return cipher().name() + "/ECB/" + padding().name();
diff --git a/src/lib/modes/ecb/ecb.h b/src/lib/modes/ecb/ecb.h
index 4d2a11d05..9fc17a80d 100644
--- a/src/lib/modes/ecb/ecb.h
+++ b/src/lib/modes/ecb/ecb.h
@@ -1,6 +1,7 @@
 /*
 * ECB Mode
 * (C) 1999-2009,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -31,6 +32,9 @@ class BOTAN_DLL ECB_Mode : public Cipher_Mode
       bool valid_nonce_length(size_t n) const override;
 
       void clear() override;
+
+      void reset() override;
+
    protected:
       ECB_Mode(BlockCipher* cipher, BlockCipherModePaddingMethod* padding);
 
diff --git a/src/lib/modes/stream_mode.h b/src/lib/modes/stream_mode.h
index 3a0c8574c..83b0543c9 100644
--- a/src/lib/modes/stream_mode.h
+++ b/src/lib/modes/stream_mode.h
@@ -1,5 +1,6 @@
 /*
 * (C) 2015 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -44,7 +45,13 @@ class BOTAN_DLL Stream_Cipher_Mode : public Cipher_Mode
 
       std::string name() const override { return m_cipher->name(); }
 
-      void clear() override { return m_cipher->clear(); }
+      void clear() override
+         {
+         m_cipher->clear();
+         reset();
+         }
+
+      void reset() override { /* no msg state */ return; }
 
    private:
       void start_msg(const byte nonce[], size_t nonce_len) override
diff --git a/src/lib/modes/xts/xts.cpp b/src/lib/modes/xts/xts.cpp
index 4b697ae6c..13dc932ea 100644
--- a/src/lib/modes/xts/xts.cpp
+++ b/src/lib/modes/xts/xts.cpp
@@ -1,6 +1,7 @@
 /*
 * XTS Mode
 * (C) 2009,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -61,6 +62,11 @@ void XTS_Mode::clear()
    {
    m_cipher->clear();
    m_tweak_cipher->clear();
+   reset();
+   }
+
+void XTS_Mode::reset()
+   {
    zeroise(m_tweak);
    }
 
diff --git a/src/lib/modes/xts/xts.h b/src/lib/modes/xts/xts.h
index 1216251c2..6d53b4312 100644
--- a/src/lib/modes/xts/xts.h
+++ b/src/lib/modes/xts/xts.h
@@ -1,6 +1,7 @@
 /*
 * XTS mode, from IEEE P1619
 * (C) 2009,2013 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -32,6 +33,9 @@ class BOTAN_DLL XTS_Mode : public Cipher_Mode
       bool valid_nonce_length(size_t n) const override;
 
       void clear() override;
+
+      void reset() override;
+
    protected:
       explicit XTS_Mode(BlockCipher* cipher);
 
diff --git a/src/lib/tls/tls_cbc/tls_cbc.cpp b/src/lib/tls/tls_cbc/tls_cbc.cpp
index ef397e44d..bd9ce2528 100644
--- a/src/lib/tls/tls_cbc/tls_cbc.cpp
+++ b/src/lib/tls/tls_cbc/tls_cbc.cpp
@@ -1,8 +1,9 @@
 /*
 * TLS CBC Record Handling
 * (C) 2012,2013,2014,2015,2016 Jack Lloyd
-*     2016 Juraj Somorovsky
-*     2016 Matthias Gierlings
+* (C) 2016 Juraj Somorovsky
+* (C) 2016 Matthias Gierlings
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -46,7 +47,14 @@ void TLS_CBC_HMAC_AEAD_Mode::clear()
    {
    cipher().clear();
    mac().clear();
+   reset();
+   }
+
+void TLS_CBC_HMAC_AEAD_Mode::reset()
+   {
    cbc_state().clear();
+   m_ad.clear();
+   m_msg.clear();
    }
 
 std::string TLS_CBC_HMAC_AEAD_Mode::name() const
diff --git a/src/lib/tls/tls_cbc/tls_cbc.h b/src/lib/tls/tls_cbc/tls_cbc.h
index 846774998..c448879fb 100644
--- a/src/lib/tls/tls_cbc/tls_cbc.h
+++ b/src/lib/tls/tls_cbc/tls_cbc.h
@@ -1,6 +1,7 @@
 /*
 * TLS CBC+HMAC AEAD
 * (C) 2016 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -41,6 +42,8 @@ class TLS_CBC_HMAC_AEAD_Mode : public AEAD_Mode
 
       void clear() override final;
 
+      void reset() override final;
+
  protected:
       TLS_CBC_HMAC_AEAD_Mode(const std::string& cipher_name,
                              size_t cipher_keylen,
diff --git a/src/tests/test_aead.cpp b/src/tests/test_aead.cpp
index e7756d5bb..1558c0d30 100644
--- a/src/tests/test_aead.cpp
+++ b/src/tests/test_aead.cpp
@@ -1,5 +1,6 @@
 /*
 * (C) 2014,2015,2016 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -7,7 +8,7 @@
 #include "tests.h"
 
 #if defined(BOTAN_HAS_AEAD_MODES)
-#include <botan/aead.h>
+  #include <botan/aead.h>
 #endif
 
 namespace Botan_Tests {
@@ -23,76 +24,237 @@ class AEAD_Tests : public Text_Based_Test
          Text_Based_Test("aead", {"Key", "Nonce", "In", "Out"}, {"AD"})
          {}
 
-      Test::Result run_one_test(const std::string& algo, const VarMap& vars) override
+      Test::Result test_enc(const std::vector<uint8_t>& key, const std::vector<uint8_t>& nonce,
+                            const std::vector<uint8_t>& input, const std::vector<uint8_t>& expected,
+                            const std::vector<uint8_t>& ad, const std::string& algo)
          {
-         const std::vector<uint8_t> key      = get_req_bin(vars, "Key");
-         const std::vector<uint8_t> nonce    = get_opt_bin(vars, "Nonce");
-         const std::vector<uint8_t> input    = get_req_bin(vars, "In");
-         const std::vector<uint8_t> expected = get_req_bin(vars, "Out");
-         const std::vector<uint8_t> ad       = get_opt_bin(vars, "AD");
-
          Test::Result result(algo);
 
          std::unique_ptr<Botan::AEAD_Mode> enc(Botan::get_aead(algo, Botan::ENCRYPTION));
-         std::unique_ptr<Botan::AEAD_Mode> dec(Botan::get_aead(algo, Botan::DECRYPTION));
 
-         if(!enc || !dec)
-            {
-            result.note_missing(algo);
-            return result;
-            }
+         // First some tests for reset() to make sure it resets what we need it to
+         // set garbage values
+         enc->set_key(mutate_vec(key));
+         enc->set_ad(mutate_vec(ad));
+         enc->start(mutate_vec(nonce));
+
+         Botan::secure_vector<byte> garbage = Test::rng().random_vec(enc->update_granularity());
+         enc->update(garbage);
+
+         // reset message specific state
+         enc->reset();
 
+         // now try to encrypt with correct values
          enc->set_key(key);
-         enc->set_associated_data_vec(ad);
+         enc->set_ad(ad);
          enc->start(nonce);
 
          Botan::secure_vector<uint8_t> buf(input.begin(), input.end());
-         // TODO: should first update if possible
-         enc->finish(buf);
 
-         result.test_eq("encrypt", buf, expected);
+         // have to check here first if input is empty if not we can test update() and eventually process()
+         if(buf.empty())
+            {
+            enc->finish(buf);
+            result.test_eq("encrypt with empty input", buf, expected);
+            }
+         else
+            {
+            // test finish() with full input
+            enc->finish(buf);
+            result.test_eq("encrypt", buf, expected);
+
+            // additionally test update() if possible
+            const size_t update_granularity = enc->update_granularity();
+            if(input.size() > update_granularity)
+               {
+               // reset state first
+               enc->reset();
+
+               enc->set_ad(ad);
+               enc->start(nonce);
+
+               buf.assign(input.begin(), input.end());
+               size_t input_length = buf.size();
+               size_t offset = 0;
+               uint8_t* p = buf.data();
+               Botan::secure_vector<uint8_t> block(update_granularity);
+               Botan::secure_vector<uint8_t> ciphertext(enc->output_length(buf.size()));
+               while(input_length > update_granularity && ((input_length - update_granularity) >= enc->minimum_final_size()))
+                  {
+                  block.assign(p, p + update_granularity);
+                  enc->update(block);
+                  p += update_granularity;
+                  input_length -= update_granularity;
+                  buffer_insert(ciphertext, 0 + offset, block);
+                  offset += update_granularity;
+                  }
+
+               // encrypt remaining bytes
+               block.assign(p, p + input_length);
+               enc->finish(block);
+               buffer_insert(ciphertext, 0 + offset, block);
+
+               result.test_eq("encrypt", ciphertext, expected);
+               }
+
+            // additionally test process() if possible
+            size_t min_final_bytes = enc->minimum_final_size();
+            if(input.size() > (update_granularity + min_final_bytes))
+               {
+               // again reset state first
+               enc->reset();
+
+               enc->set_ad(ad);
+               enc->start(nonce);
+
+               buf.assign(input.begin(), input.end());
 
-         buf.assign(expected.begin(), expected.end());
+               // we can process at max input.size()
+               const size_t max_blocks_to_process = (input.size() - min_final_bytes) / update_granularity;
+               const size_t bytes_to_process = max_blocks_to_process * update_granularity;
 
+               const size_t bytes_written = enc->process(buf.data(), bytes_to_process);
+
+               result.test_eq("correct number of bytes processed", bytes_written, bytes_to_process);
+
+               const size_t remaining = input.size() - bytes_to_process;
+
+               enc->finish(buf, bytes_to_process);
+               result.test_eq("encrypt", buf, expected);
+               }
+            }
+         return result;
+         }
+
+      Test::Result test_dec(const std::vector<uint8_t>& key, const std::vector<uint8_t>& nonce,
+                            const std::vector<uint8_t>& input, const std::vector<uint8_t>& expected,
+                            const std::vector<uint8_t>& ad, const std::string& algo)
+         {
+         Test::Result result(algo);
+
+         std::unique_ptr<Botan::AEAD_Mode> dec(Botan::get_aead(algo, Botan::DECRYPTION));
+
+         // First some tests for reset() to make sure it resets what we need it to
+         // set garbage values
+         dec->set_key(mutate_vec(key));
+         dec->set_ad(mutate_vec(ad));
+         dec->start(mutate_vec(nonce));
+
+         Botan::secure_vector<byte> garbage = Test::rng().random_vec(dec->update_granularity());
+         dec->update(garbage);
+
+         // reset message specific state
+         dec->reset();
+
+         Botan::secure_vector<uint8_t> buf(input.begin(), input.end());
          try
             {
+            // now try to decrypt with correct values
             dec->set_key(key);
-            dec->set_associated_data_vec(ad);
+            dec->set_ad(ad);
             dec->start(nonce);
+
+            // test finish() with full input
             dec->finish(buf);
+            result.test_eq("decrypt", buf, expected);
+
+            // additionally test update() if possible
+            const size_t update_granularity = dec->update_granularity();
+            if(input.size() > update_granularity)
+               {
+               // reset state first
+               dec->reset();
+
+               dec->set_ad(ad);
+               dec->start(nonce);
+
+               buf.assign(input.begin(), input.end());
+               size_t input_length = buf.size();
+               size_t offset = 0;
+               uint8_t* p = buf.data();
+               Botan::secure_vector<uint8_t> block(update_granularity);
+               Botan::secure_vector<uint8_t> plaintext(dec->output_length(buf.size()));
+               while((input_length > update_granularity) && ((input_length - update_granularity) >= dec->minimum_final_size()))
+                  {
+                  block.assign(p, p + update_granularity);
+                  dec->update(block);
+                  p += update_granularity;
+                  input_length -= update_granularity;
+                  buffer_insert(plaintext, 0 + offset, block);
+                  offset += update_granularity;
+                  }
+
+               // decrypt remaining bytes
+               block.assign(p, p + input_length);
+               dec->finish(block);
+               buffer_insert(plaintext, 0 + offset, block);
+
+               result.test_eq("decrypt", plaintext, expected);
+               }
+
+            // additionally test process() if possible
+            const size_t min_final_size = dec->minimum_final_size();
+            if(input.size() > (update_granularity + min_final_size))
+               {
+               // again reset state first
+               dec->reset();
+
+               dec->set_ad(ad);
+               dec->start(nonce);
+
+               buf.assign(input.begin(), input.end());
+
+               // we can process at max input.size()
+               const size_t max_blocks_to_process = (input.size() - min_final_size) / update_granularity;
+               const size_t bytes_to_process = max_blocks_to_process * update_granularity;
+
+               const size_t bytes_written = dec->process(buf.data(), bytes_to_process);
+
+               result.test_eq("correct number of bytes processed", bytes_written, bytes_to_process);
+
+               const size_t remaining = input.size() - bytes_to_process;
+
+               dec->finish(buf, bytes_to_process);
+               result.test_eq("decrypt", buf, expected);
+               }
+
             }
          catch(Botan::Exception& e)
             {
-            result.test_failure("Failure processing AEAD ciphertext");
+            result.test_failure("Failure processing AEAD ciphertext", e.what());
             }
 
-         if(enc->authenticated())
-            {
-            const std::vector<byte> mutated_input = mutate_vec(expected, true);
-            buf.assign(mutated_input.begin(), mutated_input.end());
+         // test decryption with modified ciphertext
+         const std::vector<byte> mutated_input = mutate_vec(input, true);
+         buf.assign(mutated_input.begin(), mutated_input.end());
 
-            dec->start(nonce);
+         dec->reset();
 
-            try
-               {
-               dec->finish(buf);
-               result.test_failure("accepted modified message", mutated_input);
-               }
-            catch(Botan::Integrity_Failure&)
-               {
-               result.test_note("correctly rejected modified message");
-               }
-            catch(std::exception& e)
-               {
-               result.test_failure("unexpected error while rejecting modified message", e.what());
-               }
+         dec->set_ad(ad);
+         dec->start(nonce);
+
+         try
+            {
+            dec->finish(buf);
+            result.test_failure("accepted modified message", mutated_input);
+            }
+         catch(Botan::Integrity_Failure&)
+            {
+            result.test_success("correctly rejected modified message");
+            }
+         catch(std::exception& e)
+            {
+            result.test_failure("unexpected error while rejecting modified message", e.what());
             }
 
+         // test decryption with modified nonce
          if(nonce.size() > 0)
             {
-            buf.assign(expected.begin(), expected.end());
+            buf.assign(input.begin(), input.end());
             std::vector<byte> bad_nonce = mutate_vec(nonce);
 
+            dec->reset();
+            dec->set_ad(ad);
             dec->start(bad_nonce);
 
             try
@@ -102,7 +264,7 @@ class AEAD_Tests : public Text_Based_Test
                }
             catch(Botan::Integrity_Failure&)
                {
-               result.test_note("correctly rejected modified nonce");
+               result.test_success("correctly rejected modified nonce");
                }
             catch(std::exception& e)
                {
@@ -110,21 +272,23 @@ class AEAD_Tests : public Text_Based_Test
                }
             }
 
+         // test decryption with modified associated_data
          const std::vector<byte> bad_ad = mutate_vec(ad, true);
 
-         dec->set_associated_data_vec(bad_ad);
+         dec->reset();
+         dec->set_ad(bad_ad);
 
          dec->start(nonce);
 
          try
             {
-            buf.assign(expected.begin(), expected.end());
+            buf.assign(input.begin(), input.end());
             dec->finish(buf);
             result.test_failure("accepted message with modified ad", bad_ad);
             }
          catch(Botan::Integrity_Failure&)
             {
-            result.test_note("correctly rejected modified ad");
+            result.test_success("correctly rejected modified ad");
             }
          catch(std::exception& e)
             {
@@ -133,6 +297,41 @@ class AEAD_Tests : public Text_Based_Test
 
          return result;
          }
+
+      Test::Result run_one_test(const std::string& algo, const VarMap& vars) override
+         {
+         const std::vector<uint8_t> key      = get_req_bin(vars, "Key");
+         const std::vector<uint8_t> nonce    = get_opt_bin(vars, "Nonce");
+         const std::vector<uint8_t> input    = get_req_bin(vars, "In");
+         const std::vector<uint8_t> expected = get_req_bin(vars, "Out");
+         const std::vector<uint8_t> ad       = get_opt_bin(vars, "AD");
+
+         Test::Result result(algo);
+
+         std::unique_ptr<Botan::AEAD_Mode> enc(Botan::get_aead(algo, Botan::ENCRYPTION));
+         std::unique_ptr<Botan::AEAD_Mode> dec(Botan::get_aead(algo, Botan::DECRYPTION));
+
+         if(!enc || !dec)
+            {
+            result.note_missing(algo);
+            return result;
+            }
+
+         // must be authenticated
+         result.test_eq("Encryption algo is an authenticated mode", enc->authenticated(), true);
+         result.test_eq("Decryption algo is an authenticated mode", dec->authenticated(), true);
+
+         // test enc
+         result.merge(test_enc(key, nonce, input, expected, ad, algo));
+
+         // test dec
+         result.merge(test_dec(key, nonce, expected, input, ad, algo));
+
+         enc->clear();
+         dec->clear();
+
+         return result;
+         }
    };
 
 BOTAN_REGISTER_TEST("aead", AEAD_Tests);
diff --git a/src/tests/test_modes.cpp b/src/tests/test_modes.cpp
index ada4d5b82..4949d1c98 100644
--- a/src/tests/test_modes.cpp
+++ b/src/tests/test_modes.cpp
@@ -1,5 +1,6 @@
 /*
 * (C) 2014,2015 Jack Lloyd
+* (C) 2016 Daniel Neus, Rohde & Schwarz Cybersecurity
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -44,22 +45,90 @@ class Cipher_Mode_Tests : public Text_Based_Test
 
          result.test_eq("mode not authenticated", enc->authenticated(), false);
 
+         // Test to make sure reset() resets what we need it to
+         enc->set_key(mutate_vec(key));
+         Botan::secure_vector<byte> garbage = Test::rng().random_vec(enc->update_granularity());
+         enc->start(mutate_vec(nonce));
+         enc->update(garbage);
+
+         enc->reset();
+
          enc->set_key(key);
          enc->start(nonce);
 
          Botan::secure_vector<uint8_t> buf(input.begin(), input.end());
          // TODO: should first update if possible
          enc->finish(buf);
-
          result.test_eq("encrypt", buf, expected);
 
+         // additionally test process() if possible
+         size_t update_granularity = enc->update_granularity();
+         size_t input_length = input.size();
+         size_t min_final_bytes = enc->minimum_final_size();
+         if(input_length > (update_granularity + min_final_bytes))
+            {
+            // reset state first
+            enc->reset();
+
+            enc->start(nonce);
+            buf.assign(input.begin(), input.end());
+
+            // we can process at max input_length
+            const size_t max_blocks_to_process = (input_length - min_final_bytes) / update_granularity;
+            const size_t bytes_to_process = max_blocks_to_process * update_granularity;
+
+            const size_t bytes_written = enc->process(buf.data(), bytes_to_process);
+
+            result.test_eq("correct number of bytes processed", bytes_written, bytes_to_process);
+
+            const size_t remaining = input_length - bytes_to_process;
+
+            enc->finish(buf, bytes_to_process);
+            result.test_eq("encrypt", buf, expected);
+            }
+
+         // decryption
          buf.assign(expected.begin(), expected.end());
 
+         // Test to make sure reset() resets what we need it to
+         dec->set_key(mutate_vec(key));
+         garbage = Test::rng().random_vec(dec->update_granularity());
+         dec->start(mutate_vec(nonce));
+         dec->update(garbage);
+
+         dec->reset();
+
          dec->set_key(key);
          dec->start(nonce);
          dec->finish(buf);
          result.test_eq("decrypt", buf, input);
 
+         // additionally test process() if possible
+         update_granularity = dec->update_granularity();
+         input_length = expected.size();
+         min_final_bytes = dec->minimum_final_size();
+         if(input_length > (update_granularity + min_final_bytes))
+            {
+            // reset state first
+            dec->reset();
+
+            dec->start(nonce);
+            buf.assign(expected.begin(), expected.end());
+
+            // we can process at max input_length
+            const size_t max_blocks_to_process = (input_length - min_final_bytes) / update_granularity;
+            const size_t bytes_to_process = max_blocks_to_process * update_granularity;
+
+            const size_t bytes_written = dec->process(buf.data(), bytes_to_process);
+
+            result.test_eq("correct number of bytes processed", bytes_written, bytes_to_process);
+
+            const size_t remaining = input_length - bytes_to_process;
+
+            dec->finish(buf, bytes_to_process);
+            result.test_eq("decrypt", buf, input);
+            }
+
          enc->clear();
          dec->clear();