Add AEAD based on ChaCha20 and Poly1305 defined in draft-irtf-cfrg-chacha20-poly1305-03

4 files changed, 246 insertions, 0 deletions

diff --git a/src/lib/modes/aead/aead.cpp b/src/lib/modes/aead/aead.cpp
index e8316ec63..ee410f031 100644
--- a/src/lib/modes/aead/aead.cpp
+++ b/src/lib/modes/aead/aead.cpp
@@ -29,10 +29,24 @@
   #include <botan/ocb.h>
 #endif
 
+#if defined(BOTAN_HAS_AEAD_CHACHA20_POLY1305)
+  #include <botan/chacha20poly1305.h>
+#endif
+
 namespace Botan {
 
 AEAD_Mode* get_aead(const std::string& algo_spec, Cipher_Dir direction)
    {
+#if defined(BOTAN_HAS_AEAD_CHACHA20_POLY1305)
+   if(algo_spec == "ChaCha20Poly1305")
+      {
+      if(direction == ENCRYPTION)
+         return new ChaCha20Poly1305_Encryption;
+      else
+         return new ChaCha20Poly1305_Decryption;
+      }
+#endif
+
    Algorithm_Factory& af = global_state().algorithm_factory();
 
    const std::vector<std::string> algo_parts = split_on(algo_spec, '/');
diff --git a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp
new file mode 100644
index 000000000..6f835ca6b
--- /dev/null
+++ b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.cpp
@@ -0,0 +1,136 @@
+/*
+* ChaCha20Poly1305 AEAD
+* (C) 2014 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/chacha20poly1305.h>
+#include <botan/chacha.h>
+#include <botan/poly1305.h>
+#include <botan/loadstor.h>
+#include <algorithm>
+
+namespace Botan {
+
+void ChaCha20Poly1305_Mode::clear()
+   {
+   m_chacha.reset();
+   m_poly1305.reset();
+   m_ad.clear();
+   m_ctext_len = 0;
+   }
+
+void ChaCha20Poly1305_Mode::key_schedule(const byte key[], size_t length)
+   {
+   if(!m_chacha.get())
+      m_chacha.reset(new ChaCha);
+   m_chacha->set_key(key, length);
+   }
+
+void ChaCha20Poly1305_Mode::set_associated_data(const byte ad[], size_t length)
+   {
+   if(m_ctext_len)
+      throw std::runtime_error("Too late to set AD for ChaCha20Poly1305");
+   m_ad.assign(ad, ad + length);
+   }
+
+void ChaCha20Poly1305_Mode::update_len(size_t len)
+   {
+   byte len8[8] = { 0 };
+   store_le(static_cast<u64bit>(len), len8);
+   m_poly1305->update(len8, 8);
+   }
+
+secure_vector<byte> ChaCha20Poly1305_Mode::start_raw(const byte nonce[], size_t nonce_len)
+   {
+   if(!valid_nonce_length(nonce_len))
+      throw Invalid_IV_Length(name(), nonce_len);
+
+   m_ctext_len = 0;
+
+   m_chacha->set_iv(nonce, nonce_len);
+
+   secure_vector<byte> zeros(64);
+   m_chacha->encrypt(zeros);
+
+   if(!m_poly1305.get())
+      m_poly1305.reset(new Poly1305);
+   m_poly1305->set_key(&zeros[0], 32);
+   // Remainder of output is discard
+
+   m_poly1305->update(m_ad);
+   for(size_t i = 0; i != 16 - m_ad.size() % 16; ++i)
+      m_poly1305->update(0);
+
+   return secure_vector<byte>();
+   }
+
+void ChaCha20Poly1305_Encryption::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_chacha->cipher1(buf, sz);
+   m_poly1305->update(buf, sz); // poly1305 of ciphertext
+   m_ctext_len += sz;
+   }
+
+void ChaCha20Poly1305_Encryption::finish(secure_vector<byte>& buffer, size_t offset)
+   {
+   update(buffer, offset);
+   for(size_t i = 0; i != 16 - m_ctext_len % 16; ++i)
+      m_poly1305->update(0);
+   update_len(m_ad.size());
+   update_len(m_ctext_len);
+
+   const secure_vector<byte> mac = m_poly1305->final();
+   buffer += std::make_pair(&mac[0], tag_size());
+   m_ctext_len = 0;
+   }
+
+void ChaCha20Poly1305_Decryption::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_poly1305->update(buf, sz); // poly1305 of ciphertext
+   m_chacha->cipher1(buf, sz);
+   m_ctext_len += sz;
+   }
+
+void ChaCha20Poly1305_Decryption::finish(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];
+
+   BOTAN_ASSERT(sz >= tag_size(), "Have the tag as part of final input");
+
+   const size_t remaining = sz - tag_size();
+
+   if(remaining)
+      {
+      m_poly1305->update(buf, remaining); // poly1305 of ciphertext
+      m_chacha->cipher1(buf, remaining);
+      m_ctext_len += remaining;
+      }
+
+   for(size_t i = 0; i != 16 - m_ctext_len % 16; ++i)
+      m_poly1305->update(0);
+   update_len(m_ad.size());
+   update_len(m_ctext_len);
+   const secure_vector<byte> mac = m_poly1305->final();
+
+   const byte* included_tag = &buf[remaining];
+
+   m_ctext_len = 0;
+
+   if(!same_mem(&mac[0], included_tag, tag_size()))
+      throw Integrity_Failure("ChaCha20Poly1305 tag check failed");
+   buffer.resize(offset + remaining);
+   }
+
+}
diff --git a/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
new file mode 100644
index 000000000..de4560be7
--- /dev/null
+++ b/src/lib/modes/aead/chacha20poly1305/chacha20poly1305.h
@@ -0,0 +1,90 @@
+/*
+* ChaCha20Poly1305 AEAD
+* (C) 2014 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_AEAD_CHACHA20_POLY1305_H__
+#define BOTAN_AEAD_CHACHA20_POLY1305_H__
+
+#include <botan/aead.h>
+#include <botan/stream_cipher.h>
+#include <botan/mac.h>
+
+namespace Botan {
+
+/**
+* Base class
+* See draft-irtf-cfrg-chacha20-poly1305-03 for specification
+*/
+class BOTAN_DLL ChaCha20Poly1305_Mode : public AEAD_Mode
+   {
+   public:
+      void set_associated_data(const byte ad[], size_t ad_len) override;
+
+      std::string name() const override { return "ChaCha20Poly1305"; }
+
+      size_t update_granularity() const override { return 64; }
+
+      Key_Length_Specification key_spec() const override
+         { return Key_Length_Specification(32); }
+
+      bool valid_nonce_length(size_t n) const override
+         { return (n == 12); }
+
+      size_t tag_size() const override { return 16; }
+
+      void clear() override;
+   protected:
+      std::unique_ptr<StreamCipher> m_chacha;
+      std::unique_ptr<MessageAuthenticationCode> m_poly1305;
+
+      secure_vector<byte> m_ad;
+      size_t m_ctext_len = 0;
+
+      void update_len(size_t len);
+   private:
+      secure_vector<byte> start_raw(const byte nonce[], size_t nonce_len) override;
+
+      void key_schedule(const byte key[], size_t length) override;
+   };
+
+/**
+* ChaCha20Poly1305 Encryption
+*/
+class BOTAN_DLL ChaCha20Poly1305_Encryption : public ChaCha20Poly1305_Mode
+   {
+   public:
+      size_t output_length(size_t input_length) const override
+         { return input_length + tag_size(); }
+
+      size_t minimum_final_size() const override { return 0; }
+
+      void update(secure_vector<byte>& blocks, size_t offset = 0) override;
+
+      void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
+   };
+
+/**
+* ChaCha20Poly1305 Decryption
+*/
+class BOTAN_DLL ChaCha20Poly1305_Decryption : public ChaCha20Poly1305_Mode
+   {
+   public:
+      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(); }
+
+      void update(secure_vector<byte>& blocks, size_t offset = 0) override;
+
+      void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
+   };
+
+}
+
+#endif
diff --git a/src/lib/modes/aead/chacha20poly1305/info.txt b/src/lib/modes/aead/chacha20poly1305/info.txt
new file mode 100644
index 000000000..f03f2797e
--- /dev/null
+++ b/src/lib/modes/aead/chacha20poly1305/info.txt
@@ -0,0 +1,6 @@
+define AEAD_CHACHA20_POLY1305 20141228
+
+<requires>
+chacha
+poly1305
+</requires>