1 files changed, 0 insertions, 439 deletions
diff --git a/src/axolotl.cpp b/src/axolotl.cpp
deleted file mode 100644
index 0f0d226..0000000
--- a/src/axolotl.cpp
+++ /dev/null
@@ -1,439 +0,0 @@
-/* Copyright 2015 OpenMarket Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-#include "axolotl/axolotl.hh"
-#include "axolotl/message.hh"
-#include "axolotl/memory.hh"
-
-#include <cstring>
-
-namespace {
-
-std::uint8_t PROTOCOL_VERSION = 3;
-std::size_t MAC_LENGTH = 8;
-std::size_t KEY_LENGTH = axolotl::Curve25519PublicKey::LENGTH;
-std::uint8_t MESSAGE_KEY_SEED[1] = {0x01};
-std::uint8_t CHAIN_KEY_SEED[1] = {0x02};
-std::size_t MAX_MESSAGE_GAP = 2000;
-
-void create_chain_key(
-    axolotl::SharedKey const & root_key,
-    axolotl::Curve25519KeyPair const & our_key,
-    axolotl::Curve25519PublicKey const & their_key,
-    axolotl::KdfInfo const & info,
-    axolotl::SharedKey & new_root_key,
-    axolotl::ChainKey & new_chain_key
-) {
-    axolotl::SharedKey secret;
-    axolotl::curve25519_shared_secret(our_key, their_key, secret);
-    std::uint8_t derived_secrets[64];
-    axolotl::hkdf_sha256(
-        secret, sizeof(secret),
-        root_key, sizeof(root_key),
-        info.ratchet_info, info.ratchet_info_length,
-        derived_secrets, sizeof(derived_secrets)
-    );
-    std::memcpy(new_root_key, derived_secrets, 32);
-    std::memcpy(new_chain_key.key, derived_secrets + 32, 32);
-    new_chain_key.index = 0;
-    axolotl::unset(derived_secrets);
-    axolotl::unset(secret);
-}
-
-
-void advance_chain_key(
-    axolotl::ChainKey const & chain_key,
-    axolotl::ChainKey & new_chain_key
-) {
-    axolotl::hmac_sha256(
-        chain_key.key, sizeof(chain_key.key),
-        CHAIN_KEY_SEED, sizeof(CHAIN_KEY_SEED),
-        new_chain_key.key
-    );
-    new_chain_key.index = chain_key.index + 1;
-}
-
-
-void create_message_keys(
-    axolotl::ChainKey const & chain_key,
-    axolotl::KdfInfo const & info,
-    axolotl::MessageKey & message_key
-) {
-    axolotl::SharedKey secret;
-    axolotl::hmac_sha256(
-        chain_key.key, sizeof(chain_key.key),
-        MESSAGE_KEY_SEED, sizeof(MESSAGE_KEY_SEED),
-        secret
-    );
-    std::uint8_t derived_secrets[80];
-    axolotl::hkdf_sha256(
-        secret, sizeof(secret),
-        NULL, 0,
-        info.message_info, info.message_info_length,
-        derived_secrets, sizeof(derived_secrets)
-    );
-    std::memcpy(message_key.cipher_key.key, derived_secrets, 32);
-    std::memcpy(message_key.mac_key, derived_secrets + 32, 32);
-    std::memcpy(message_key.iv.iv, derived_secrets + 64, 16);
-    message_key.index = chain_key.index;
-    axolotl::unset(derived_secrets);
-    axolotl::unset(secret);
-}
-
-
-bool verify_mac(
-    axolotl::MessageKey const & message_key,
-    std::uint8_t const * input,
-    axolotl::MessageReader const & reader
-) {
-    std::uint8_t mac[axolotl::HMAC_SHA256_OUTPUT_LENGTH];
-    axolotl::hmac_sha256(
-        message_key.mac_key, sizeof(message_key.mac_key),
-        input, reader.body_length,
-        mac
-    );
-
-    bool result = std::memcmp(mac, reader.mac, MAC_LENGTH) == 0;
-    axolotl::unset(mac);
-    return result;
-}
-
-
-bool verify_mac_for_existing_chain(
-    axolotl::Session const & session,
-    axolotl::ChainKey const & chain,
-    std::uint8_t const * input,
-    axolotl::MessageReader const & reader
-) {
-    if (reader.counter < chain.index) {
-        return false;
-    }
-
-    /* Limit the number of hashes we're prepared to compute */
-    if (reader.counter - chain.index > MAX_MESSAGE_GAP) {
-        return false;
-    }
-
-    axolotl::ChainKey new_chain = chain;
-
-    while (new_chain.index < reader.counter) {
-        advance_chain_key(new_chain, new_chain);
-    }
-
-    axolotl::MessageKey message_key;
-    create_message_keys(new_chain, session.kdf_info, message_key);
-
-    bool result = verify_mac(message_key, input, reader);
-    axolotl::unset(new_chain);
-    return result;
-}
-
-
-bool verify_mac_for_new_chain(
-    axolotl::Session const & session,
-    std::uint8_t const * input,
-    axolotl::MessageReader const & reader
-) {
-    axolotl::SharedKey new_root_key;
-    axolotl::ReceiverChain new_chain;
-
-    /* They shouldn't move to a new chain until we've sent them a message
-     * acknowledging the last one */
-    if (session.sender_chain.empty()) {
-        return false;
-    }
-
-    /* Limit the number of hashes we're prepared to compute */
-    if (reader.counter > MAX_MESSAGE_GAP) {
-        return false;
-    }
-    std::memcpy(
-        new_chain.ratchet_key.public_key, reader.ratchet_key, KEY_LENGTH
-    );
-
-    create_chain_key(
-        session.root_key, session.sender_chain[0].ratchet_key,
-        new_chain.ratchet_key, session.kdf_info,
-        new_root_key, new_chain.chain_key
-    );
-
-    bool result = verify_mac_for_existing_chain(
-        session, new_chain.chain_key, input, reader
-    );
-    axolotl::unset(new_root_key);
-    axolotl::unset(new_chain);
-    return result;
-}
-
-} // namespace
-
-
-axolotl::Session::Session(
-    axolotl::KdfInfo const & kdf_info
-) : kdf_info(kdf_info), last_error(axolotl::ErrorCode::SUCCESS) {
-}
-
-
-void axolotl::Session::initialise_as_bob(
-    std::uint8_t const * shared_secret, std::size_t shared_secret_length,
-    axolotl::Curve25519PublicKey const & their_ratchet_key
-) {
-    std::uint8_t derived_secrets[64];
-    axolotl::hkdf_sha256(
-        shared_secret, shared_secret_length,
-        NULL, 0,
-        kdf_info.root_info, kdf_info.root_info_length,
-        derived_secrets, sizeof(derived_secrets)
-    );
-    receiver_chains.insert();
-    std::memcpy(root_key, derived_secrets, 32);
-    std::memcpy(receiver_chains[0].chain_key.key, derived_secrets + 32, 32);
-    receiver_chains[0].ratchet_key = their_ratchet_key;
-    axolotl::unset(derived_secrets);
-}
-
-
-void axolotl::Session::initialise_as_alice(
-    std::uint8_t const * shared_secret, std::size_t shared_secret_length,
-    axolotl::Curve25519KeyPair const & our_ratchet_key
-) {
-    std::uint8_t derived_secrets[64];
-    axolotl::hkdf_sha256(
-        shared_secret, shared_secret_length,
-        NULL, 0,
-        kdf_info.root_info, kdf_info.root_info_length,
-        derived_secrets, sizeof(derived_secrets)
-    );
-    sender_chain.insert();
-    std::memcpy(root_key, derived_secrets, 32);
-    std::memcpy(sender_chain[0].chain_key.key, derived_secrets + 32, 32);
-    sender_chain[0].ratchet_key = our_ratchet_key;
-    axolotl::unset(derived_secrets);
-}
-
-
-std::size_t axolotl::Session::encrypt_max_output_length(
-    std::size_t plaintext_length
-) {
-    std::size_t counter = 0;
-    if (!sender_chain.empty()) {
-        counter = sender_chain[0].chain_key.index;
-    }
-    std::size_t padded = axolotl::aes_encrypt_cbc_length(plaintext_length);
-    return axolotl::encode_message_length(
-        counter, KEY_LENGTH, padded, MAC_LENGTH
-    );
-}
-
-
-std::size_t axolotl::Session::encrypt_random_length() {
-    return sender_chain.empty() ? KEY_LENGTH : 0;
-}
-
-
-std::size_t axolotl::Session::encrypt(
-    std::uint8_t const * plaintext, std::size_t plaintext_length,
-    std::uint8_t const * random, std::size_t random_length,
-    std::uint8_t * output, std::size_t max_output_length
-) {
-    if (random_length < encrypt_random_length()) {
-        last_error = axolotl::ErrorCode::NOT_ENOUGH_RANDOM;
-        return std::size_t(-1);
-    }
-    if (max_output_length < encrypt_max_output_length(plaintext_length)) {
-        last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL;
-        return std::size_t(-1);
-    }
-
-    if (sender_chain.empty()) {
-        sender_chain.insert();
-        axolotl::generate_key(random, sender_chain[0].ratchet_key);
-        create_chain_key(
-            root_key,
-            sender_chain[0].ratchet_key,
-            receiver_chains[0].ratchet_key,
-            kdf_info,
-            root_key, sender_chain[0].chain_key
-        );
-    }
-
-    MessageKey keys;
-    create_message_keys(sender_chain[0].chain_key, kdf_info, keys);
-    advance_chain_key(sender_chain[0].chain_key, sender_chain[0].chain_key);
-
-    std::size_t padded = axolotl::aes_encrypt_cbc_length(plaintext_length);
-    std::uint32_t counter = keys.index;
-    const Curve25519PublicKey &ratchet_key = sender_chain[0].ratchet_key;
-
-    axolotl::MessageWriter writer(axolotl::encode_message(
-        PROTOCOL_VERSION, counter, KEY_LENGTH, padded, output
-    ));
-
-    std::memcpy(writer.ratchet_key, ratchet_key.public_key, KEY_LENGTH);
-
-    axolotl::aes_encrypt_cbc(
-        keys.cipher_key, keys.iv,
-        plaintext, plaintext_length,
-        writer.ciphertext
-    );
-
-    std::uint8_t mac[axolotl::HMAC_SHA256_OUTPUT_LENGTH];
-    axolotl::hmac_sha256(
-        keys.mac_key, sizeof(keys.mac_key),
-        output, writer.body_length,
-        mac
-    );
-    std::memcpy(writer.mac, mac, MAC_LENGTH);
-
-    axolotl::unset(keys);
-    return writer.body_length + MAC_LENGTH;
-}
-
-
-std::size_t axolotl::Session::decrypt_max_plaintext_length(
-    std::size_t input_length
-) {
-    return input_length;
-}
-
-
-std::size_t axolotl::Session::decrypt(
-    std::uint8_t const * input, std::size_t input_length,
-    std::uint8_t * plaintext, std::size_t max_plaintext_length
-) {
-    if (max_plaintext_length < decrypt_max_plaintext_length(input_length)) {
-        last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL;
-        return std::size_t(-1);
-    }
-
-    axolotl::MessageReader reader(axolotl::decode_message(
-        input, input_length, MAC_LENGTH
-    ));
-
-    if (reader.version != PROTOCOL_VERSION) {
-        last_error = axolotl::ErrorCode::BAD_MESSAGE_VERSION;
-        return std::size_t(-1);
-    }
-
-    if (reader.body_length == 0 || reader.ratchet_key_length != KEY_LENGTH) {
-        last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
-        return std::size_t(-1);
-    }
-
-    ReceiverChain * chain = NULL;
-    for (axolotl::ReceiverChain & receiver_chain : receiver_chains) {
-        if (0 == std::memcmp(
-                receiver_chain.ratchet_key.public_key, reader.ratchet_key,
-                KEY_LENGTH
-        )) {
-            chain = &receiver_chain;
-            break;
-        }
-    }
-
-    if (!chain) {
-        if (!verify_mac_for_new_chain(*this, input, reader)) {
-            last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-            return std::size_t(-1);
-        }
-    } else {
-        if (chain->chain_key.index > reader.counter) {
-            /* Chain already advanced beyond the key for this message
-             * Check if the message keys are in the skipped key list. */
-            for (axolotl::SkippedMessageKey & skipped : skipped_message_keys) {
-                if (reader.counter == skipped.message_key.index
-                        && 0 == std::memcmp(
-                            skipped.ratchet_key.public_key, reader.ratchet_key,
-                            KEY_LENGTH
-                        )
-                ) {
-                    /* Found the key for this message. Check the MAC. */
-                    if (!verify_mac(skipped.message_key, input, reader)) {
-                        last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-                        return std::size_t(-1);
-                    }
-
-                    std::size_t result = axolotl::aes_decrypt_cbc(
-                        skipped.message_key.cipher_key,
-                        skipped.message_key.iv,
-                        reader.ciphertext, reader.ciphertext_length,
-                        plaintext
-                    );
-
-                    if (result == std::size_t(-1)) {
-                        last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-                        return result;
-                    }
-
-                    /* Remove the key from the skipped keys now that we've
-                     * decoded the message it corresponds to. */
-                    axolotl::unset(skipped);
-                    skipped_message_keys.erase(&skipped);
-                    return result;
-                }
-            }
-            /* No matching keys for the message, fail with bad mac */
-            last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-            return std::size_t(-1);
-        } else if (!verify_mac_for_existing_chain(
-               *this, chain->chain_key, input, reader
-        )) {
-            last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-            return std::size_t(-1);
-        }
-    }
-
-    if (!chain) {
-        /* They have started using a new empheral ratchet key.
-         * We need to derive a new set of chain keys.
-         * We can discard our previous empheral ratchet key.
-         * We will generate a new key when we send the next message. */
-        chain = receiver_chains.insert();
-        std::memcpy(
-            chain->ratchet_key.public_key, reader.ratchet_key, KEY_LENGTH
-        );
-        create_chain_key(
-            root_key, sender_chain[0].ratchet_key, chain->ratchet_key,
-            kdf_info, root_key, chain->chain_key
-        );
-        axolotl::unset(sender_chain[0]);
-        sender_chain.erase(sender_chain.begin());
-    }
-
-    while (chain->chain_key.index < reader.counter) {
-        axolotl::SkippedMessageKey & key = *skipped_message_keys.insert();
-        create_message_keys(chain->chain_key, kdf_info, key.message_key);
-        key.ratchet_key = chain->ratchet_key;
-        advance_chain_key(chain->chain_key, chain->chain_key);
-    }
-
-    axolotl::MessageKey message_key;
-    create_message_keys(chain->chain_key, kdf_info, message_key);
-    std::size_t result = axolotl::aes_decrypt_cbc(
-        message_key.cipher_key,
-        message_key.iv,
-        reader.ciphertext, reader.ciphertext_length,
-        plaintext
-    );
-    axolotl::unset(message_key);
-
-    advance_chain_key(chain->chain_key, chain->chain_key);
-
-    if (result == std::size_t(-1)) {
-        last_error = axolotl::ErrorCode::BAD_MESSAGE_MAC;
-        return std::size_t(-1);
-    } else {
-        return result;
-    }
-}