Commit a08d7063 authored by Mark Haines's avatar Mark Haines
Browse files

Add methods for pickling and unpickling sessions

parent 8123ce62
......@@ -25,6 +25,7 @@ struct Curve25519PublicKey {
struct Curve25519KeyPair : public Curve25519PublicKey {
static const int LENGTH = 64;
std::uint8_t private_key[32];
};
......
......@@ -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(
......
......@@ -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
) {
......
......@@ -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])
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