diff --git a/include/axolotl/crypto.hh b/include/axolotl/crypto.hh
index d772f466465efbd4cde18c486e9398794893f000..42e4b61d518e98d1e33e391cb9504286fdf9f4fd 100644
--- a/include/axolotl/crypto.hh
+++ b/include/axolotl/crypto.hh
@@ -25,6 +25,7 @@ struct Curve25519PublicKey {
struct Curve25519KeyPair : public Curve25519PublicKey {
+ static const int LENGTH = 64;
std::uint8_t private_key[32];
};
diff --git a/include/axolotl/ratchet.hh b/include/axolotl/ratchet.hh
index 9d7ff9ad2f0359c2738ced9e36f23d840c9b1639..cf41359ac56b719a40cf1abb5af8ea0cd842cbce 100644
--- a/include/axolotl/ratchet.hh
+++ b/include/axolotl/ratchet.hh
@@ -84,7 +84,7 @@ struct Session {
);
/** A some strings identifing the application to feed into the KDF. */
- KdfInfo kdf_info;
+ const KdfInfo &kdf_info;
/** The last error that happened encypting or decrypting a message. */
ErrorCode last_error;
@@ -121,6 +121,24 @@ struct Session {
Curve25519KeyPair const & our_ratchet_key
);
+ /** The number of bytes needed to persist the current session. */
+ std::size_t pickle_max_output_length();
+
+ /** Persists a session as a sequence of bytes, encrypting using a key
+ * Returns the number of output bytes used. */
+ std::size_t pickle(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t * output, std::size_t max_output_length
+ );
+
+ /** Loads a session from a sequence of bytes, decrypting using a key.
+ * Returns 0 on success, or std::size_t(-1) on failure. The last_error
+ * will be BAD_SESSION_KEY if the supplied key is incorrect. */
+ std::size_t unpickle(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t * input, std::size_t input_length
+ );
+
/** The maximum number of bytes of output the encrypt method will write for
* a given message length. */
std::size_t encrypt_max_output_length(
diff --git a/src/ratchet.cpp b/src/ratchet.cpp
index ccb8e738e858265a063b2aa9b1f51acc42451326..b17e1620ff53a6047c478cbdab747e9b803c7108 100644
--- a/src/ratchet.cpp
+++ b/src/ratchet.cpp
@@ -223,6 +223,143 @@ void axolotl::Session::initialise_as_alice(
}
+std::size_t axolotl::Session::pickle_max_output_length() {
+ std::size_t counter_length = 4;
+ std::size_t send_chain_length = counter_length + 64 + 32;
+ std::size_t recv_chain_length = counter_length + 32 + 32;
+ std::size_t skip_key_length = counter_length + 32 + 32 + 32 + 16;
+ std::size_t pickle_length = 3 * counter_length + 32;
+ pickle_length += sender_chain.size() * send_chain_length;
+ pickle_length += receiver_chains.size() * recv_chain_length;
+ pickle_length += skipped_message_keys.size() * skip_key_length;
+ return axolotl::aes_encrypt_cbc_length(pickle_length) + MAC_LENGTH;
+}
+
+namespace {
+
+std::uint8_t * pickle_counter(
+ std::uint8_t * output, std::uint32_t value
+) {
+ unsigned i = 4;
+ output += 4;
+ while (i--) { *(--output) = value; value >>= 8; }
+ return output + 4;
+}
+
+std::uint8_t * unpickle_counter(
+ std::uint8_t *input, std::uint32_t &value
+) {
+ unsigned i = 4;
+ value = 0;
+ while (i--) { value <<= 8; value |= *(input++); }
+ return input;
+}
+
+std::uint8_t * pickle_bytes(
+ std::uint8_t * output, std::size_t count, std::uint8_t const * bytes
+) {
+ std::memcpy(output, bytes, count);
+ return output + count;
+}
+
+std::uint8_t * unpickle_bytes(
+ std::uint8_t * input, std::size_t count, std::uint8_t * bytes
+) {
+ std::memcpy(bytes, input, count);
+ return input + count;
+}
+
+} // namespace
+
+
+std::size_t axolotl::Session::pickle(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t * output, std::size_t max_output_length
+) {
+ std::uint8_t * pos = output;
+ if (max_output_length < pickle_max_output_length()) {
+ last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL;
+ return std::size_t(-1);
+ }
+
+ pos = pickle_counter(pos, sender_chain.size());
+ pos = pickle_counter(pos, receiver_chains.size());
+ pos = pickle_counter(pos, skipped_message_keys.size());
+ pos = pickle_bytes(pos, 32, root_key);
+ for (const axolotl::SenderChain &chain : sender_chain) {
+ pos = pickle_counter(pos, chain.chain_key.index);
+ pos = pickle_bytes(pos, 32, chain.chain_key.key);
+ pos = pickle_bytes(pos, 32, chain.ratchet_key.public_key);
+ pos = pickle_bytes(pos, 32, chain.ratchet_key.private_key);
+ }
+ for (const axolotl::ReceiverChain &chain : receiver_chains) {
+ pos = pickle_counter(pos, chain.chain_key.index);
+ pos = pickle_bytes(pos, 32, chain.chain_key.key);
+ pos = pickle_bytes(pos, 32, chain.ratchet_key.public_key);
+ }
+ for (const axolotl::SkippedMessageKey &key : skipped_message_keys) {
+ pos = pickle_counter(pos, key.message_key.index);
+ pos = pickle_bytes(pos, 32, key.message_key.cipher_key.key);
+ pos = pickle_bytes(pos, 32, key.message_key.mac_key);
+ pos = pickle_bytes(pos, 16, key.message_key.iv.iv);
+ pos = pickle_bytes(pos, 32, key.ratchet_key.public_key);
+ }
+}
+
+std::size_t axolotl::Session::unpickle(
+ std::uint8_t const * key, std::size_t key_length,
+ std::uint8_t * input, std::size_t input_length
+) {
+
+ std::uint8_t * pos = input;
+ std::uint8_t * end = input + input_length;
+ std::uint32_t send_chain_num, recv_chain_num, skipped_num;
+
+ if (end - pos < 4 * 3 + 32) {} // input too small.
+
+ pos = unpickle_counter(pos, send_chain_num);
+ pos = unpickle_counter(pos, recv_chain_num);
+ pos = unpickle_counter(pos, skipped_num);
+ pos = unpickle_bytes(pos, 32, root_key);
+
+ if (end - pos < send_chain_num * (32 * 3 + 4)) {} // input too small.
+
+ while (send_chain_num--) {
+ axolotl::SenderChain & chain = *sender_chain.insert(
+ sender_chain.end()
+ );
+ pos = unpickle_counter(pos, chain.chain_key.index);
+ pos = unpickle_bytes(pos, 32, chain.chain_key.key);
+ pos = unpickle_bytes(pos, 32, chain.ratchet_key.public_key);
+ pos = unpickle_bytes(pos, 32, chain.ratchet_key.private_key);
+ }
+
+ if (end - pos < recv_chain_num * (32 * 2 + 4)) {} // input too small.
+
+ while (recv_chain_num--) {
+ axolotl::ReceiverChain & chain = *receiver_chains.insert(
+ receiver_chains.end()
+ );
+ pos = unpickle_counter(pos, chain.chain_key.index);
+ pos = unpickle_bytes(pos, 32, chain.chain_key.key);
+ pos = unpickle_bytes(pos, 32, chain.ratchet_key.public_key);
+ }
+
+ if (end - pos < skipped_num * (32 * 3 + 16 + 4)) {} // input too small.
+
+ while (skipped_num--) {
+ axolotl::SkippedMessageKey &key = *skipped_message_keys.insert(
+ skipped_message_keys.end()
+ );
+ pos = unpickle_counter(pos, key.message_key.index);
+ pos = unpickle_bytes(pos, 32, key.message_key.cipher_key.key);
+ pos = unpickle_bytes(pos, 32, key.message_key.mac_key);
+ pos = unpickle_bytes(pos, 16, key.message_key.iv.iv);
+ pos = unpickle_bytes(pos, 32, key.ratchet_key.public_key);
+ }
+}
+
+
std::size_t axolotl::Session::encrypt_max_output_length(
std::size_t plaintext_length
) {
diff --git a/test.py b/test.py
index 06d4552477313c8ddffecd90dbb7e2a5012b57de..e1ef5c9b92a92a4627f836d89a3a55681837483e 100755
--- a/test.py
+++ b/test.py
@@ -26,7 +26,11 @@ source_files = glob.glob("src/*.cpp")
compile_args = "g++ -g -O0 -Itests/include -Iinclude -Ilib --std=c++11".split()
compile_args += source_files
+def run(args):
+ print " ".join(args)
+ subprocess.check_call(args)
+
for test_file in test_files:
exe_file = "build/" + test_file[5:-4]
- subprocess.check_call(compile_args + [test_file, "-o", exe_file])
- subprocess.check_call([exe_file])
+ run(compile_args + [test_file, "-o", exe_file])
+ run([exe_file])