--- /dev/null
+/* Copyright 2015, 2016 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 "olm/session.hh"
+#include "olm/cipher.h"
+#include "olm/crypto.h"
+#include "olm/account.hh"
+#include "olm/memory.hh"
+#include "olm/message.hh"
+#include "olm/pickle.hh"
+
+#include <cstring>
+#include <stdio.h>
+
+namespace {
+
+static const std::uint8_t PROTOCOL_VERSION = 0x3;
+
+static const std::uint8_t ROOT_KDF_INFO[] = "OLM_ROOT";
+static const std::uint8_t RATCHET_KDF_INFO[] = "OLM_RATCHET";
+static const std::uint8_t CIPHER_KDF_INFO[] = "OLM_KEYS";
+
+static const olm::KdfInfo OLM_KDF_INFO = {
+ ROOT_KDF_INFO, sizeof(ROOT_KDF_INFO) - 1,
+ RATCHET_KDF_INFO, sizeof(RATCHET_KDF_INFO) - 1
+};
+
+static const struct _olm_cipher_aes_sha_256 OLM_CIPHER =
+ OLM_CIPHER_INIT_AES_SHA_256(CIPHER_KDF_INFO);
+
+} // namespace
+
+olm::Session::Session(
+) : ratchet(OLM_KDF_INFO, OLM_CIPHER_BASE(&OLM_CIPHER)),
+ last_error(OlmErrorCode::OLM_SUCCESS),
+ received_message(false) {
+
+}
+
+
+std::size_t olm::Session::new_outbound_session_random_length() const {
+ return CURVE25519_RANDOM_LENGTH * 2;
+}
+
+
+std::size_t olm::Session::new_outbound_session(
+ olm::Account const & local_account,
+ _olm_curve25519_public_key const & identity_key,
+ _olm_curve25519_public_key const & one_time_key,
+ std::uint8_t const * random, std::size_t random_length
+) {
+ if (random_length < new_outbound_session_random_length()) {
+ last_error = OlmErrorCode::OLM_NOT_ENOUGH_RANDOM;
+ return std::size_t(-1);
+ }
+
+ _olm_curve25519_key_pair base_key;
+ _olm_crypto_curve25519_generate_key(random, &base_key);
+
+ _olm_curve25519_key_pair ratchet_key;
+ _olm_crypto_curve25519_generate_key(random + CURVE25519_RANDOM_LENGTH, &ratchet_key);
+
+ _olm_curve25519_key_pair const & alice_identity_key_pair = (
+ local_account.identity_keys.curve25519_key
+ );
+
+ received_message = false;
+ alice_identity_key = alice_identity_key_pair.public_key;
+ alice_base_key = base_key.public_key;
+ bob_one_time_key = one_time_key;
+
+ // Calculate the shared secret S via triple DH
+ std::uint8_t secret[3 * CURVE25519_SHARED_SECRET_LENGTH];
+ std::uint8_t * pos = secret;
+
+ _olm_crypto_curve25519_shared_secret(&alice_identity_key_pair, &one_time_key, pos);
+ pos += CURVE25519_SHARED_SECRET_LENGTH;
+ _olm_crypto_curve25519_shared_secret(&base_key, &identity_key, pos);
+ pos += CURVE25519_SHARED_SECRET_LENGTH;
+ _olm_crypto_curve25519_shared_secret(&base_key, &one_time_key, pos);
+
+ ratchet.initialise_as_alice(secret, sizeof(secret), ratchet_key);
+
+ olm::unset(base_key);
+ olm::unset(ratchet_key);
+ olm::unset(secret);
+
+ return std::size_t(0);
+}
+
+namespace {
+
+static bool check_message_fields(
+ olm::PreKeyMessageReader & reader, bool have_their_identity_key
+) {
+ bool ok = true;
+ ok = ok && (have_their_identity_key || reader.identity_key);
+ if (reader.identity_key) {
+ ok = ok && reader.identity_key_length == CURVE25519_KEY_LENGTH;
+ }
+ ok = ok && reader.message;
+ ok = ok && reader.base_key;
+ ok = ok && reader.base_key_length == CURVE25519_KEY_LENGTH;
+ ok = ok && reader.one_time_key;
+ ok = ok && reader.one_time_key_length == CURVE25519_KEY_LENGTH;
+ return ok;
+}
+
+} // namespace
+
+
+std::size_t olm::Session::new_inbound_session(
+ olm::Account & local_account,
+ _olm_curve25519_public_key const * their_identity_key,
+ std::uint8_t const * one_time_key_message, std::size_t message_length
+) {
+ olm::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, one_time_key_message, message_length);
+
+ if (!check_message_fields(reader, their_identity_key)) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+
+ if (reader.identity_key && their_identity_key) {
+ bool same = 0 == std::memcmp(
+ their_identity_key->public_key, reader.identity_key, CURVE25519_KEY_LENGTH
+ );
+ if (!same) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_KEY_ID;
+ return std::size_t(-1);
+ }
+ }
+
+ olm::load_array(alice_identity_key.public_key, reader.identity_key);
+ olm::load_array(alice_base_key.public_key, reader.base_key);
+ olm::load_array(bob_one_time_key.public_key, reader.one_time_key);
+
+ olm::MessageReader message_reader;
+ decode_message(
+ message_reader, reader.message, reader.message_length,
+ ratchet.ratchet_cipher->ops->mac_length(ratchet.ratchet_cipher)
+ );
+
+ if (!message_reader.ratchet_key
+ || message_reader.ratchet_key_length != CURVE25519_KEY_LENGTH) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+
+ _olm_curve25519_public_key ratchet_key;
+ olm::load_array(ratchet_key.public_key, message_reader.ratchet_key);
+
+ olm::OneTimeKey const * our_one_time_key = local_account.lookup_key(
+ bob_one_time_key
+ );
+
+ if (!our_one_time_key) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_KEY_ID;
+ return std::size_t(-1);
+ }
+
+ _olm_curve25519_key_pair const & bob_identity_key = (
+ local_account.identity_keys.curve25519_key
+ );
+ _olm_curve25519_key_pair const & bob_one_time_key = our_one_time_key->key;
+
+ // Calculate the shared secret S via triple DH
+ std::uint8_t secret[CURVE25519_SHARED_SECRET_LENGTH * 3];
+ std::uint8_t * pos = secret;
+ _olm_crypto_curve25519_shared_secret(&bob_one_time_key, &alice_identity_key, pos);
+ pos += CURVE25519_SHARED_SECRET_LENGTH;
+ _olm_crypto_curve25519_shared_secret(&bob_identity_key, &alice_base_key, pos);
+ pos += CURVE25519_SHARED_SECRET_LENGTH;
+ _olm_crypto_curve25519_shared_secret(&bob_one_time_key, &alice_base_key, pos);
+
+ ratchet.initialise_as_bob(secret, sizeof(secret), ratchet_key);
+
+ olm::unset(secret);
+
+ return std::size_t(0);
+}
+
+
+std::size_t olm::Session::session_id_length() const {
+ return SHA256_OUTPUT_LENGTH;
+}
+
+
+std::size_t olm::Session::session_id(
+ std::uint8_t * id, std::size_t id_length
+) {
+ if (id_length < session_id_length()) {
+ last_error = OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
+ return std::size_t(-1);
+ }
+ std::uint8_t tmp[CURVE25519_KEY_LENGTH * 3];
+ std::uint8_t * pos = tmp;
+ pos = olm::store_array(pos, alice_identity_key.public_key);
+ pos = olm::store_array(pos, alice_base_key.public_key);
+ pos = olm::store_array(pos, bob_one_time_key.public_key);
+ _olm_crypto_sha256(tmp, sizeof(tmp), id);
+ return session_id_length();
+}
+
+
+bool olm::Session::matches_inbound_session(
+ _olm_curve25519_public_key const * their_identity_key,
+ std::uint8_t const * one_time_key_message, std::size_t message_length
+) const {
+ olm::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, one_time_key_message, message_length);
+
+ if (!check_message_fields(reader, their_identity_key)) {
+ return false;
+ }
+
+ bool same = true;
+ if (reader.identity_key) {
+ same = same && 0 == std::memcmp(
+ reader.identity_key, alice_identity_key.public_key, CURVE25519_KEY_LENGTH
+ );
+ }
+ if (their_identity_key) {
+ same = same && 0 == std::memcmp(
+ their_identity_key->public_key, alice_identity_key.public_key,
+ CURVE25519_KEY_LENGTH
+ );
+ }
+ same = same && 0 == std::memcmp(
+ reader.base_key, alice_base_key.public_key, CURVE25519_KEY_LENGTH
+ );
+ same = same && 0 == std::memcmp(
+ reader.one_time_key, bob_one_time_key.public_key, CURVE25519_KEY_LENGTH
+ );
+ return same;
+}
+
+
+olm::MessageType olm::Session::encrypt_message_type() const {
+ if (received_message) {
+ return olm::MessageType::MESSAGE;
+ } else {
+ return olm::MessageType::PRE_KEY;
+ }
+}
+
+
+std::size_t olm::Session::encrypt_message_length(
+ std::size_t plaintext_length
+) const {
+ std::size_t message_length = ratchet.encrypt_output_length(
+ plaintext_length
+ );
+
+ if (received_message) {
+ return message_length;
+ }
+
+ return encode_one_time_key_message_length(
+ CURVE25519_KEY_LENGTH,
+ CURVE25519_KEY_LENGTH,
+ CURVE25519_KEY_LENGTH,
+ message_length
+ );
+}
+
+
+std::size_t olm::Session::encrypt_random_length() const {
+ return ratchet.encrypt_random_length();
+}
+
+
+std::size_t olm::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 * message, std::size_t message_length
+) {
+ if (message_length < encrypt_message_length(plaintext_length)) {
+ last_error = OlmErrorCode::OLM_OUTPUT_BUFFER_TOO_SMALL;
+ return std::size_t(-1);
+ }
+ std::uint8_t * message_body;
+ std::size_t message_body_length = ratchet.encrypt_output_length(
+ plaintext_length
+ );
+
+ if (received_message) {
+ message_body = message;
+ } else {
+ olm::PreKeyMessageWriter writer;
+ encode_one_time_key_message(
+ writer,
+ PROTOCOL_VERSION,
+ CURVE25519_KEY_LENGTH,
+ CURVE25519_KEY_LENGTH,
+ CURVE25519_KEY_LENGTH,
+ message_body_length,
+ message
+ );
+ olm::store_array(writer.one_time_key, bob_one_time_key.public_key);
+ olm::store_array(writer.identity_key, alice_identity_key.public_key);
+ olm::store_array(writer.base_key, alice_base_key.public_key);
+ message_body = writer.message;
+ }
+
+ std::size_t result = ratchet.encrypt(
+ plaintext, plaintext_length,
+ random, random_length,
+ message_body, message_body_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = OlmErrorCode::OLM_SUCCESS;
+ return result;
+ }
+
+ return result;
+}
+
+
+std::size_t olm::Session::decrypt_max_plaintext_length(
+ MessageType message_type,
+ std::uint8_t const * message, std::size_t message_length
+) {
+ std::uint8_t const * message_body;
+ std::size_t message_body_length;
+ if (message_type == olm::MessageType::MESSAGE) {
+ message_body = message;
+ message_body_length = message_length;
+ } else {
+ olm::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, message, message_length);
+ if (!reader.message) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+ message_body = reader.message;
+ message_body_length = reader.message_length;
+ }
+
+ std::size_t result = ratchet.decrypt_max_plaintext_length(
+ message_body, message_body_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = OlmErrorCode::OLM_SUCCESS;
+ }
+ return result;
+}
+
+
+std::size_t olm::Session::decrypt(
+ olm::MessageType message_type,
+ std::uint8_t const * message, std::size_t message_length,
+ std::uint8_t * plaintext, std::size_t max_plaintext_length
+) {
+ std::uint8_t const * message_body;
+ std::size_t message_body_length;
+ if (message_type == olm::MessageType::MESSAGE) {
+ message_body = message;
+ message_body_length = message_length;
+ } else {
+ olm::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, message, message_length);
+ if (!reader.message) {
+ last_error = OlmErrorCode::OLM_BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+ message_body = reader.message;
+ message_body_length = reader.message_length;
+ }
+
+ std::size_t result = ratchet.decrypt(
+ message_body, message_body_length, plaintext, max_plaintext_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = OlmErrorCode::OLM_SUCCESS;
+ return result;
+ }
+
+ received_message = true;
+ return result;
+}
+
+// make the description end with "..." instead of stopping abruptly with no
+// warning
+void elide_description(char *end) {
+ end[-3] = '.';
+ end[-2] = '.';
+ end[-1] = '.';
+ end[0] = '\0';
+}
+
+void olm::Session::describe(char *describe_buffer, size_t buflen) {
+ // how much of the buffer is remaining (this is an int rather than a size_t
+ // because it will get compared to the return value from snprintf)
+ int remaining = buflen;
+ // do nothing if we have a zero-length buffer, or if buflen > INT_MAX,
+ // resulting in an overflow
+ if (remaining <= 0) return;
+
+ describe_buffer[0] = '\0';
+ // we need at least 23 characters to get any sort of meaningful
+ // information, so bail if we don't have that. (But more importantly, we
+ // need it to be at least 4 so that elide_description doesn't go out of
+ // bounds.)
+ if (remaining < 23) return;
+
+ int size;
+
+ // check that snprintf didn't return an error or reach the end of the buffer
+#define CHECK_SIZE_AND_ADVANCE \
+ if (size > remaining) { \
+ return elide_description(describe_buffer + remaining - 1); \
+ } else if (size > 0) { \
+ describe_buffer += size; \
+ remaining -= size; \
+ } else { \
+ return; \
+ }
+
+ size = snprintf(
+ describe_buffer, remaining,
+ "sender chain index: %ld ", ratchet.sender_chain[0].chain_key.index
+ );
+ CHECK_SIZE_AND_ADVANCE;
+
+ size = snprintf(describe_buffer, remaining, "receiver chain indices:");
+ CHECK_SIZE_AND_ADVANCE;
+
+ for (size_t i = 0; i < ratchet.receiver_chains.size(); ++i) {
+ size = snprintf(
+ describe_buffer, remaining,
+ " %ld", ratchet.receiver_chains[i].chain_key.index
+ );
+ CHECK_SIZE_AND_ADVANCE;
+ }
+
+ size = snprintf(describe_buffer, remaining, " skipped message keys:");
+ CHECK_SIZE_AND_ADVANCE;
+
+ for (size_t i = 0; i < ratchet.skipped_message_keys.size(); ++i) {
+ size = snprintf(
+ describe_buffer, remaining,
+ " %ld", ratchet.skipped_message_keys[i].message_key.index
+ );
+ CHECK_SIZE_AND_ADVANCE;
+ }
+#undef CHECK_SIZE_AND_ADVANCE
+}
+
+namespace {
+// the master branch writes pickle version 1; the logging_enabled branch writes
+// 0x80000001.
+static const std::uint32_t SESSION_PICKLE_VERSION = 1;
+}
+
+std::size_t olm::pickle_length(
+ Session const & value
+) {
+ std::size_t length = 0;
+ length += olm::pickle_length(SESSION_PICKLE_VERSION);
+ length += olm::pickle_length(value.received_message);
+ length += olm::pickle_length(value.alice_identity_key);
+ length += olm::pickle_length(value.alice_base_key);
+ length += olm::pickle_length(value.bob_one_time_key);
+ length += olm::pickle_length(value.ratchet);
+ return length;
+}
+
+
+std::uint8_t * olm::pickle(
+ std::uint8_t * pos,
+ Session const & value
+) {
+ pos = olm::pickle(pos, SESSION_PICKLE_VERSION);
+ pos = olm::pickle(pos, value.received_message);
+ pos = olm::pickle(pos, value.alice_identity_key);
+ pos = olm::pickle(pos, value.alice_base_key);
+ pos = olm::pickle(pos, value.bob_one_time_key);
+ pos = olm::pickle(pos, value.ratchet);
+ return pos;
+}
+
+
+std::uint8_t const * olm::unpickle(
+ std::uint8_t const * pos, std::uint8_t const * end,
+ Session & value
+) {
+ uint32_t pickle_version;
+ pos = olm::unpickle(pos, end, pickle_version); UNPICKLE_OK(pos);
+
+ bool includes_chain_index;
+ switch (pickle_version) {
+ case 1:
+ includes_chain_index = false;
+ break;
+
+ case 0x80000001UL:
+ includes_chain_index = true;
+ break;
+
+ default:
+ value.last_error = OlmErrorCode::OLM_UNKNOWN_PICKLE_VERSION;
+ return nullptr;
+ }
+
+ pos = olm::unpickle(pos, end, value.received_message); UNPICKLE_OK(pos);
+ pos = olm::unpickle(pos, end, value.alice_identity_key); UNPICKLE_OK(pos);
+ pos = olm::unpickle(pos, end, value.alice_base_key); UNPICKLE_OK(pos);
+ pos = olm::unpickle(pos, end, value.bob_one_time_key); UNPICKLE_OK(pos);
+ pos = olm::unpickle(pos, end, value.ratchet, includes_chain_index); UNPICKLE_OK(pos);
+
+ return pos;
+}
projects / matrix_esp_thesis / blobdiff