diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index c6647bd..289fca4 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -11,7 +11,10 @@ set(HEADER_FILES
 		include/chiaki/takion.h
 		include/chiaki/senkusha.h
 		include/chiaki/nagare.h
-		include/chiaki/mirai.h)
+		include/chiaki/mirai.h
+		include/chiaki/ecdh.h
+		include/chiaki/launchspec.h
+		include/chiaki/random.h)
 
 set(SOURCE_FILES
 		src/common.c
@@ -27,7 +30,10 @@ set(SOURCE_FILES
 		src/utils.h
 		src/pb_utils.h
 		src/nagare.c
-		src/mirai.c)
+		src/mirai.c
+		src/ecdh.c
+		src/launchspec.c
+		src/random.c)
 
 add_subdirectory(protobuf)
 include_directories("${NANOPB_SOURCE_DIR}")
diff --git a/lib/include/chiaki/ecdh.h b/lib/include/chiaki/ecdh.h
new file mode 100644
index 0000000..50162ad
--- /dev/null
+++ b/lib/include/chiaki/ecdh.h
@@ -0,0 +1,39 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef CHIAKI_ECDH_H
+#define CHIAKI_ECDH_H
+
+#include "common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct chiaki_ecdh_t
+{
+
+} ChiakiECDH;
+
+CHIAKI_EXPORT ChiakiErrorCode chiaki_ecdh_init(ChiakiECDH *ecdh);
+CHIAKI_EXPORT void chiaki_ecdh_fini(ChiakiECDH *ecdh);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // CHIAKI_ECDH_H
diff --git a/lib/include/chiaki/launchspec.h b/lib/include/chiaki/launchspec.h
new file mode 100644
index 0000000..a23716c
--- /dev/null
+++ b/lib/include/chiaki/launchspec.h
@@ -0,0 +1,43 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef CHIAKI_LAUNCHSPEC_H
+#define CHIAKI_LAUNCHSPEC_H
+
+#include "common.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct chiaki_launch_spec_t
+{
+	unsigned int mtu;
+	unsigned int rtt;
+	uint8_t *handshake_key;
+} ChiakiLaunchSpec;
+
+CHIAKI_EXPORT ssize_t chiaki_launchspec_format(char *buf, size_t buf_size, ChiakiLaunchSpec *launch_spec);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // CHIAKI_LAUNCHSPEC_H
diff --git a/lib/include/chiaki/random.h b/lib/include/chiaki/random.h
new file mode 100644
index 0000000..ee35f20
--- /dev/null
+++ b/lib/include/chiaki/random.h
@@ -0,0 +1,36 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef CHIAKI_RANDOM_H
+#define CHIAKI_RANDOM_H
+
+#include "common.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+CHIAKI_EXPORT ChiakiErrorCode chiaki_random_bytes(uint8_t *buf, size_t buf_size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // CHIAKI_RANDOM_H
diff --git a/lib/include/chiaki/session.h b/lib/include/chiaki/session.h
index 1a85128..41dbaca 100644
--- a/lib/include/chiaki/session.h
+++ b/lib/include/chiaki/session.h
@@ -36,6 +36,7 @@ extern "C" {
 
 #define CHIAKI_RP_DID_SIZE 32
 #define CHIAKI_SESSION_ID_SIZE_MAX 80
+#define CHIAKI_HANDSHAKE_KEY_SIZE 0x10
 
 typedef struct chiaki_connect_info_t
 {
@@ -96,7 +97,10 @@ typedef struct chiaki_session_t
 
 	uint8_t nonce[CHIAKI_KEY_BYTES];
 	ChiakiRPCrypt rpcrypt;
-	char session_id[CHIAKI_SESSION_ID_SIZE_MAX];
+	char session_id[CHIAKI_SESSION_ID_SIZE_MAX]; // zero-terminated
+	uint8_t handshake_key[CHIAKI_HANDSHAKE_KEY_SIZE];
+	unsigned int mtu;
+	unsigned int rtt;
 
 	ChiakiQuitReason quit_reason;
 
diff --git a/lib/src/ecdh.c b/lib/src/ecdh.c
new file mode 100644
index 0000000..0cf366d
--- /dev/null
+++ b/lib/src/ecdh.c
@@ -0,0 +1,28 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <chiaki/ecdh.h>
+
+CHIAKI_EXPORT ChiakiErrorCode chiaki_ecdh_init(ChiakiECDH *ecdh)
+{
+	return CHIAKI_ERR_SUCCESS;
+}
+
+CHIAKI_EXPORT void chiaki_ecdh_fini(ChiakiECDH *ecdh)
+{
+
+}
\ No newline at end of file
diff --git a/lib/src/launchspec.c b/lib/src/launchspec.c
new file mode 100644
index 0000000..014fe58
--- /dev/null
+++ b/lib/src/launchspec.c
@@ -0,0 +1,90 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <chiaki/launchspec.h>
+#include <chiaki/session.h>
+#include <chiaki/base64.h>
+
+#include <stdio.h>
+
+static const char launchspec_fmt[] =
+	"{"
+		"\"sessionId\":\"sessionId4321\","
+		"\"streamResolutions\":["
+			"{"
+				"\"resolution\":"
+				"{"
+					"\"width\":640,"
+					"\"height\":360"
+				"},"
+				"\"maxFps\":30,"
+				"\"score\":10"
+			"}"
+		"],"
+		"\"network\":{"
+			"\"bwKbpsSent\":2000,"
+			"\"bwLoss\":0.001000,"
+			"\"mtu\":%u," // 0
+			"\"rtt\":%u," // 1
+			"\"ports\":[53,2053]"
+		"},"
+		"\"slotId\":1,"
+		"\"appSpecification\":{"
+			"\"minFps\":30,"
+			"\"minBandwidth\":0,"
+			"\"extTitleId\":\"ps3\","
+			"\"version\":1,"
+			"\"timeLimit\":1,"
+			"\"startTimeout\":100,"
+			"\"afkTimeout\":100,"
+			"\"afkTimeoutDisconnect\":100"
+		"},"
+		"\"konan\":{"
+			"\"ps3AccessToken\":\"accessToken\","
+			"\"ps3RefreshToken\":\"refreshToken\""
+		"},\"requestGameSpecification\":{"
+			"\"model\":\"bravia_tv\","
+			"\"platform\":\"android\","
+			"\"audioChannels\":\"5.1\","
+			"\"language\":\"sp\","
+			"\"acceptButton\":\"X\","
+			"\"connectedControllers\":[\"xinput\",\"ds3\",\"ds4\"],"
+			"\"yuvCoefficient\":\"bt601\","
+			"\"videoEncoderProfile\":\"hw4.1\","
+			"\"audioEncoderProfile\":\"audio1\""
+		"},"
+		"\"userProfile\":{"
+			"\"onlineId\":\"psnId\","
+			"\"npId\":\"npId\","
+			"\"region\":\"US\","
+			"\"languagesUsed\":[\"en\",\"jp\"]"
+		"},"
+		"\"handshakeKey\":\"%s\"" // 2
+	"}";
+
+CHIAKI_EXPORT ssize_t chiaki_launchspec_format(char *buf, size_t buf_size, ChiakiLaunchSpec *launch_spec)
+{
+	char handshake_key_b64[CHIAKI_HANDSHAKE_KEY_SIZE * 2];
+	ChiakiErrorCode err = chiaki_base64_encode(launch_spec->handshake_key, CHIAKI_HANDSHAKE_KEY_SIZE, handshake_key_b64, sizeof(handshake_key_b64));
+	if(err != CHIAKI_ERR_SUCCESS)
+		return -1;
+
+	int written = snprintf(buf, buf_size, launchspec_fmt, launch_spec->mtu, launch_spec->rtt, handshake_key_b64);
+	if(written < 0 || written >= buf_size)
+		return -1;
+	return written;
+}
\ No newline at end of file
diff --git a/lib/src/nagare.c b/lib/src/nagare.c
index a8c72ef..22b652f 100644
--- a/lib/src/nagare.c
+++ b/lib/src/nagare.c
@@ -18,6 +18,8 @@
 
 #include <chiaki/nagare.h>
 #include <chiaki/session.h>
+#include <chiaki/launchspec.h>
+#include <chiaki/base64.h>
 
 #include <string.h>
 #include <assert.h>
@@ -43,6 +45,7 @@ static ChiakiErrorCode nagare_send_disconnect(ChiakiNagare *nagare);
 CHIAKI_EXPORT ChiakiErrorCode chiaki_nagare_run(ChiakiSession *session)
 {
 	ChiakiNagare *nagare = &session->nagare;
+	nagare->session = session;
 	nagare->log = &session->log;
 
 	ChiakiErrorCode err = chiaki_mirai_init(&nagare->bang_mirai);
@@ -144,20 +147,71 @@ static void nagare_takion_data(uint8_t *buf, size_t buf_size, void *user)
 	}
 }
 
+
+static bool chiaki_pb_encode_zero_encrypted_key(pb_ostream_t *stream, const pb_field_t *field, void *const *arg)
+{
+	if (!pb_encode_tag_for_field(stream, field))
+		return false;
+	uint8_t data[] = { 0, 0, 0, 0 };
+	return pb_encode_string(stream, data, sizeof(data));
+}
+
+#define LAUNCH_SPEC_JSON_BUF_SIZE 1024
+
 static ChiakiErrorCode nagare_send_big(ChiakiNagare *nagare)
 {
+	ChiakiSession *session = nagare->session;
+
+	ChiakiLaunchSpec launch_spec;
+	launch_spec.mtu = session->mtu;
+	launch_spec.rtt = session->rtt;
+	launch_spec.handshake_key = session->handshake_key;
+
+	union
+	{
+		char json[LAUNCH_SPEC_JSON_BUF_SIZE];
+		char b64[LAUNCH_SPEC_JSON_BUF_SIZE * 2];
+	} launch_spec_buf;
+	ssize_t launch_spec_json_size = chiaki_launchspec_format(launch_spec_buf.json, sizeof(launch_spec_buf.json), &launch_spec);
+	if(launch_spec_json_size != CHIAKI_ERR_SUCCESS)
+	{
+		CHIAKI_LOGE(nagare->log, "Nagare failed to format LaunchSpec json\n");
+		return CHIAKI_ERR_UNKNOWN;
+	}
+	launch_spec_json_size += 1; // we also want the trailing 0
+
+	uint8_t launch_spec_json_enc[LAUNCH_SPEC_JSON_BUF_SIZE];
+	memset(launch_spec_json_enc, 0, (size_t)launch_spec_json_size);
+	ChiakiErrorCode err = chiaki_rpcrypt_encrypt(&session->rpcrypt, 0, launch_spec_json_enc, launch_spec_json_enc,
+			(size_t)launch_spec_json_size);
+	if(err != CHIAKI_ERR_SUCCESS)
+	{
+		CHIAKI_LOGE(nagare->log, "Nagare failed to encrypt LaunchSpec\n");
+		return err;
+	}
+
+	xor_bytes(launch_spec_json_enc, (uint8_t *)launch_spec_buf.json, (size_t)launch_spec_json_size);
+	err = chiaki_base64_encode(launch_spec_json_enc, (size_t)launch_spec_json_size, launch_spec_buf.b64, sizeof(launch_spec_buf.b64));
+	if(err != CHIAKI_ERR_SUCCESS)
+	{
+		CHIAKI_LOGE(nagare->log, "Nagare failed to encode LaunchSpec as base64\n");
+		return err;
+	}
+
 	tkproto_TakionMessage msg;
 	memset(&msg, 0, sizeof(msg));
 
 	msg.type = tkproto_TakionMessage_PayloadType_BIG;
 	msg.has_big_payload = true;
 	msg.big_payload.client_version = 9;
-	msg.big_payload.session_key.arg = "";
+	msg.big_payload.session_key.arg = session->session_id;
 	msg.big_payload.session_key.funcs.encode = chiaki_pb_encode_string;
-	msg.big_payload.launch_spec.arg = "";
+	msg.big_payload.launch_spec.arg = launch_spec_buf.b64;
 	msg.big_payload.launch_spec.funcs.encode = chiaki_pb_encode_string;
-	msg.big_payload.encrypted_key.arg = "";
-	msg.big_payload.encrypted_key.funcs.encode = chiaki_pb_encode_string;
+	msg.big_payload.encrypted_key.funcs.encode = chiaki_pb_encode_zero_encrypted_key;
+
+	// TODO: msg.big_payload.ecdh_pub_key
+	// TODO: msg.big_payload.ecdh_sig
 
 	uint8_t buf[12];
 	size_t buf_size;
@@ -171,7 +225,7 @@ static ChiakiErrorCode nagare_send_big(ChiakiNagare *nagare)
 	}
 
 	buf_size = stream.bytes_written;
-	ChiakiErrorCode err = chiaki_takion_send_message_data(&nagare->takion, 0, 1, 1, buf, buf_size);
+	err = chiaki_takion_send_message_data(&nagare->takion, 0, 1, 1, buf, buf_size);
 
 	return err;
 }
diff --git a/lib/src/random.c b/lib/src/random.c
new file mode 100644
index 0000000..18960c7
--- /dev/null
+++ b/lib/src/random.c
@@ -0,0 +1,28 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <chiaki/random.h>
+
+#include <openssl/rand.h>
+
+CHIAKI_EXPORT ChiakiErrorCode chiaki_random_bytes(uint8_t *buf, size_t buf_size)
+{
+	int r = RAND_bytes(buf, (int)buf_size);
+	if(!r)
+		return CHIAKI_ERR_UNKNOWN;
+	return CHIAKI_ERR_SUCCESS;
+}
\ No newline at end of file
diff --git a/lib/src/session.c b/lib/src/session.c
index dc96193..d3bf85e 100644
--- a/lib/src/session.c
+++ b/lib/src/session.c
@@ -19,6 +19,7 @@
 #include <chiaki/session.h>
 #include <chiaki/http.h>
 #include <chiaki/base64.h>
+#include <chiaki/random.h>
 
 #include <stdlib.h>
 #include <string.h>
@@ -163,8 +164,19 @@ static void *session_thread_func(void *arg)
 		goto quit_ctrl;
 	}
 
+	// TODO: Senkusha should set that
+	session->mtu = 1454;
+	session->rtt = 12;
+
 	CHIAKI_LOGI(&session->log, "Senkusha completed successfully\n");
 
+	err = chiaki_random_bytes(session->handshake_key, sizeof(session->handshake_key));
+	if(err != CHIAKI_ERR_SUCCESS)
+	{
+		CHIAKI_LOGE(&session->log, "Session failed to generate handshake key\n");
+		goto quit_ctrl;
+	}
+
 	err = chiaki_nagare_run(session);
 	if(err != CHIAKI_ERR_SUCCESS)
 	{
@@ -375,4 +387,3 @@ static bool session_thread_request_session(ChiakiSession *session)
 	close(session_sock);
 	return response.success;
 }
-
diff --git a/lib/src/utils.h b/lib/src/utils.h
index 6d4a191..b1e2ff0 100644
--- a/lib/src/utils.h
+++ b/lib/src/utils.h
@@ -32,4 +32,15 @@ static inline ChiakiErrorCode set_port(struct sockaddr *sa, in_port_t port)
 	return CHIAKI_ERR_SUCCESS;
 }
 
+static inline void xor_bytes(uint8_t *dst, uint8_t *src, size_t sz)
+{
+	while(sz > 0)
+	{
+		*dst ^= *src;
+		dst++;
+		src++;
+		sz--;
+	}
+}
+
 #endif // CHIAKI_UTILS_H