Add CCM mode

4 files changed, 416 insertions, 2 deletions

diff --git a/src/modes/aead/aead.cpp b/src/modes/aead/aead.cpp
index 1ec7b4a4a..980a212d4 100644
--- a/src/modes/aead/aead.cpp
+++ b/src/modes/aead/aead.cpp
@@ -8,6 +8,10 @@
 #include <botan/aead.h>
 #include <botan/libstate.h>
 
+#if defined(BOTAN_HAS_AEAD_CCM)
+  #include <botan/ccm.h>
+#endif
+
 #if defined(BOTAN_HAS_AEAD_EAX)
   #include <botan/eax.h>
 #endif
@@ -34,14 +38,29 @@ AEAD_Mode* get_aead(const std::string& algo_spec, Cipher_Dir direction)
       return nullptr;
 
    const std::string cipher_name = algo_parts[0];
-   const std::string mode_name = algo_parts[1];
+   const std::vector<std::string> mode_info = parse_algorithm_name(algo_parts[1]);
 
-   const size_t tag_size = 16; // default for all current AEAD
+   if(mode_info.empty())
+      return nullptr;
+
+   const std::string mode_name = mode_info[0];
+   const size_t tag_size = (mode_info.size() > 1) ? to_u32bit(mode_info[1]) : 16;
 
    const BlockCipher* cipher = af.prototype_block_cipher(cipher_name);
    if(!cipher)
       return nullptr;
 
+#if defined(BOTAN_HAS_AEAD_CCM)
+   if(mode_name == "CCM")
+      {
+      const size_t L = (mode_info.size() > 2) ? to_u32bit(mode_info[2]) : 3;
+      if(direction == ENCRYPTION)
+         return new CCM_Encryption(cipher->clone(), tag_size, L);
+      else
+         return new CCM_Decryption(cipher->clone(), tag_size, L);
+      }
+#endif
+
 #if defined(BOTAN_HAS_AEAD_EAX)
    if(mode_name == "EAX")
       {
diff --git a/src/modes/aead/ccm/ccm.cpp b/src/modes/aead/ccm/ccm.cpp
new file mode 100644
index 000000000..898964ff4
--- /dev/null
+++ b/src/modes/aead/ccm/ccm.cpp
@@ -0,0 +1,266 @@
+/*
+* CCM Mode Encryption
+* (C) 2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/ccm.h>
+#include <botan/parsing.h>
+#include <botan/internal/xor_buf.h>
+#include <algorithm>
+
+namespace Botan {
+
+/*
+* CCM_Mode Constructor
+*/
+CCM_Mode::CCM_Mode(BlockCipher* cipher, size_t tag_size, size_t L) :
+   m_tag_size(tag_size),
+   m_L(L),
+   m_cipher(cipher)
+   {
+   if(m_cipher->block_size() != 16)
+      throw std::invalid_argument(m_cipher->name() + " cannot be used with CCM mode");
+
+   if(L < 2 || L > 8)
+      throw std::invalid_argument("Invalid CCM L value " + std::to_string(L));
+
+   if(tag_size < 4 || tag_size > 16 || tag_size % 2 != 0)
+      throw std::invalid_argument("invalid CCM tag length " + std::to_string(tag_size));
+   }
+
+void CCM_Mode::clear()
+   {
+   m_cipher.reset();
+   m_msg_buf.clear();
+   m_ad_buf.clear();
+   }
+
+std::string CCM_Mode::name() const
+   {
+   return (m_cipher->name() + "/CCM(" + std::to_string(tag_size()) + "," + std::to_string(L())) + ")";
+   }
+
+bool CCM_Mode::valid_nonce_length(size_t n) const
+   {
+   return (n == (15-L()));
+   }
+
+size_t CCM_Mode::default_nonce_size() const
+   {
+   return (15-L());
+   }
+
+size_t CCM_Mode::update_granularity() const
+   {
+   /*
+   This value does not particularly matter as regardless CCM_Mode::update
+   buffers all input, so in theory this could be 1. However as for instance
+   Transformation_Filter creates update_granularity() byte buffers, use a
+   somewhat large size to avoid bouncing on a tiny buffer.
+   */
+   return m_cipher->parallel_bytes();
+   }
+
+Key_Length_Specification CCM_Mode::key_spec() const
+   {
+   return m_cipher->key_spec();
+   }
+
+void CCM_Mode::key_schedule(const byte key[], size_t length)
+   {
+   m_cipher->set_key(key, length);
+   }
+
+void CCM_Mode::set_associated_data(const byte ad[], size_t length)
+   {
+   m_ad_buf.clear();
+
+   if(length)
+      {
+      // FIXME: support larger AD using length encoding rules
+      BOTAN_ASSERT(length < (0xFFFF - 0xFF), "Supported CCM AD length");
+
+      m_ad_buf.push_back(get_byte<u16bit>(0, length));
+      m_ad_buf.push_back(get_byte<u16bit>(1, length));
+      m_ad_buf += std::make_pair(ad, length);
+      while(m_ad_buf.size() % 16)
+         m_ad_buf.push_back(0); // pad with zeros to full block size
+      }
+   }
+
+secure_vector<byte> CCM_Mode::start(const byte nonce[], size_t nonce_len)
+   {
+   if(!valid_nonce_length(nonce_len))
+      throw Invalid_IV_Length(name(), nonce_len);
+
+   m_nonce.assign(nonce, nonce + nonce_len);
+   m_msg_buf.clear();
+
+   return secure_vector<byte>();
+   }
+
+void CCM_Mode::update(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+   const size_t sz = buffer.size() - offset;
+   byte* buf = &buffer[offset];
+
+   m_msg_buf.insert(m_msg_buf.end(), buf, buf + sz);
+   buffer.resize(offset); // truncate msg
+   }
+
+void CCM_Mode::encode_length(size_t len, byte out[])
+   {
+   const size_t len_bytes = L();
+
+   BOTAN_ASSERT(len_bytes < sizeof(size_t), "Length field fits");
+
+   for(size_t i = 0; i != len_bytes; ++i)
+      out[i] = get_byte(sizeof(size_t)-i, len);
+
+   BOTAN_ASSERT((len >> (len_bytes*8)) == 0, "Message length fits in field");
+   }
+
+void CCM_Mode::inc(secure_vector<byte>& C)
+   {
+   for(size_t i = 0; i != C.size(); ++i)
+      if(++C[C.size()-i-1])
+         break;
+   }
+
+secure_vector<byte> CCM_Mode::format_b0(size_t sz)
+   {
+   secure_vector<byte> B0(BS);
+
+   const byte b_flags = (m_ad_buf.size() ? 64 : 0) + (((tag_size()/2)-1) << 3) + (L()-1);
+
+   B0[0] = b_flags;
+   copy_mem(&B0[1], &m_nonce[0], m_nonce.size());
+   encode_length(sz, &B0[m_nonce.size()+1]);
+
+   return B0;
+   }
+
+secure_vector<byte> CCM_Mode::format_c0()
+   {
+   secure_vector<byte> C(BS);
+
+   const byte a_flags = L()-1;
+
+   C[0] = a_flags;
+   copy_mem(&C[1], &m_nonce[0], m_nonce.size());
+
+   return C;
+   }
+
+void CCM_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+
+   buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end());
+
+   const size_t sz = buffer.size() - offset;
+   byte* buf = &buffer[offset];
+
+   const secure_vector<byte>& ad = ad_buf();
+   BOTAN_ASSERT(ad.size() % BS == 0, "AD is block size multiple");
+
+   const BlockCipher& E = cipher();
+
+   secure_vector<byte> T(BS);
+   E.encrypt(format_b0(sz), T);
+
+   for(size_t i = 0; i != ad.size(); i += BS)
+      {
+      xor_buf(&T[0], &ad[i], BS);
+      E.encrypt(T);
+      }
+
+   secure_vector<byte> C = format_c0();
+   secure_vector<byte> S0(BS);
+   E.encrypt(C, S0);
+   inc(C);
+
+   secure_vector<byte> X(BS);
+
+   const byte* buf_end = &buf[sz];
+
+   while(buf != buf_end)
+      {
+      const size_t to_proc = std::min<size_t>(BS, buf_end - buf);
+
+      xor_buf(&T[0], buf, to_proc);
+      E.encrypt(T);
+
+      E.encrypt(C, X);
+      xor_buf(buf, &X[0], to_proc);
+      inc(C);
+
+      buf += to_proc;
+      }
+
+   T ^= S0;
+
+   buffer += std::make_pair(&T[0], tag_size());
+   }
+
+void CCM_Decryption::finish(secure_vector<byte>& buffer, size_t offset)
+   {
+   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
+
+   buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end());
+
+   const size_t sz = buffer.size() - offset;
+   byte* buf = &buffer[offset];
+
+   BOTAN_ASSERT(sz >= tag_size(), "We have the tag");
+
+   const secure_vector<byte>& ad = ad_buf();
+   BOTAN_ASSERT(ad.size() % BS == 0, "AD is block size multiple");
+
+   const BlockCipher& E = cipher();
+
+   secure_vector<byte> T(BS);
+   E.encrypt(format_b0(sz - tag_size()), T);
+
+   for(size_t i = 0; i != ad.size(); i += BS)
+      {
+      xor_buf(&T[0], &ad[i], BS);
+      E.encrypt(T);
+      }
+
+   secure_vector<byte> C = format_c0();
+
+   secure_vector<byte> S0(BS);
+   E.encrypt(C, S0);
+   inc(C);
+
+   secure_vector<byte> X(BS);
+
+   const byte* buf_end = &buf[sz - tag_size()];
+
+   while(buf != buf_end)
+      {
+      const size_t to_proc = std::min<size_t>(BS, buf_end - buf);
+
+      E.encrypt(C, X);
+      xor_buf(buf, &X[0], to_proc);
+      inc(C);
+
+      xor_buf(&T[0], buf, to_proc);
+      E.encrypt(T);
+
+      buf += to_proc;
+      }
+
+   T ^= S0;
+
+   if(!same_mem(&T[0], buf_end, tag_size()))
+      throw Integrity_Failure("CCM tag check failed");
+
+   buffer.resize(buffer.size() - tag_size());
+   }
+
+}
diff --git a/src/modes/aead/ccm/ccm.h b/src/modes/aead/ccm/ccm.h
new file mode 100644
index 000000000..d0a44a51d
--- /dev/null
+++ b/src/modes/aead/ccm/ccm.h
@@ -0,0 +1,128 @@
+/*
+* CCM Mode
+* (C) 2013 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_AEAD_CCM_H__
+#define BOTAN_AEAD_CCM_H__
+
+#include <botan/aead.h>
+#include <botan/block_cipher.h>
+#include <botan/stream_cipher.h>
+#include <botan/mac.h>
+#include <memory>
+
+namespace Botan {
+
+/**
+* Base class for CCM encryption and decryption
+* @see RFC 3610
+*/
+class BOTAN_DLL CCM_Mode : public AEAD_Mode
+   {
+   public:
+      secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
+
+      void update(secure_vector<byte>& blocks, size_t offset) override;
+
+      void set_associated_data(const byte ad[], size_t ad_len) override;
+
+      std::string name() const override;
+
+      size_t update_granularity() const;
+
+      Key_Length_Specification key_spec() const override;
+
+      bool valid_nonce_length(size_t) const override;
+
+      size_t default_nonce_size() const override;
+
+      void clear();
+
+      size_t tag_size() const { return m_tag_size; }
+
+   protected:
+      static const size_t BS = 16; // intrinsic to CCM definition
+
+      CCM_Mode(BlockCipher* cipher, size_t tag_size, size_t L);
+
+      size_t L() const { return m_L; }
+
+      const BlockCipher& cipher() const { return *m_cipher; }
+
+      void encode_length(size_t len, byte out[]);
+
+      void inc(secure_vector<byte>& C);
+
+      const secure_vector<byte>& ad_buf() const { return m_ad_buf; }
+
+      secure_vector<byte>& msg_buf() { return m_msg_buf; }
+
+      secure_vector<byte> format_b0(size_t msg_size);
+      secure_vector<byte> format_c0();
+   private:
+      void key_schedule(const byte key[], size_t length) override;
+
+      const size_t m_tag_size;
+      const size_t m_L;
+
+      std::unique_ptr<BlockCipher> m_cipher;
+      secure_vector<byte> m_nonce, m_msg_buf, m_ad_buf;
+   };
+
+/**
+* CCM Encryption
+*/
+class BOTAN_DLL CCM_Encryption : public CCM_Mode
+   {
+   public:
+      /**
+      * @param cipher a 128-bit block cipher
+      * @param tag_size is how big the auth tag will be (even values
+      *                 between 4 and 16 are accepted)
+      * @param L length of L parameter. The total message length
+      *           must be less than 2**L bytes, and the nonce is 15-L bytes.
+      */
+      CCM_Encryption(BlockCipher* cipher, size_t tag_size = 16, size_t L = 3) :
+         CCM_Mode(cipher, tag_size, L) {}
+
+      void finish(secure_vector<byte>& final_block, size_t offset) override;
+
+      size_t output_length(size_t input_length) const override
+         { return input_length + tag_size(); }
+
+      size_t minimum_final_size() const override { return 0; }
+   };
+
+/**
+* CCM Decryption
+*/
+class BOTAN_DLL CCM_Decryption : public CCM_Mode
+   {
+   public:
+      /**
+      * @param cipher a 128-bit block cipher
+      * @param tag_size is how big the auth tag will be (even values
+      *                 between 4 and 16 are accepted)
+      * @param L length of L parameter. The total message length
+      *           must be less than 2**L bytes, and the nonce is 15-L bytes.
+      */
+      CCM_Decryption(BlockCipher* cipher, size_t tag_size = 16, size_t L = 3) :
+         CCM_Mode(cipher, tag_size, L) {}
+
+      void finish(secure_vector<byte>& final_block, size_t offset) override;
+
+      size_t output_length(size_t input_length) const override
+         {
+         BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
+         return input_length - tag_size();
+         }
+
+      size_t minimum_final_size() const override { return tag_size(); }
+   };
+
+}
+
+#endif
diff --git a/src/modes/aead/ccm/info.txt b/src/modes/aead/ccm/info.txt
new file mode 100644
index 000000000..8ec85ec7d
--- /dev/null
+++ b/src/modes/aead/ccm/info.txt
@@ -0,0 +1 @@
+define AEAD_CCM