diff --git a/Cargo.lock b/Cargo.lock
index af3045b..65a5184 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,12 +11,66 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cpufeatures"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e4c1eaa2012c47becbbad2ab175484c2a84d1185b566fb2cc5b8707343dfe58"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "itransfer"
 version = "0.1.0"
@@ -24,8 +78,25 @@ dependencies = [
  "bincode",
  "byteorder",
  "serde",
+ "sha2",
+ "sha3",
 ]
 
+[[package]]
+name = "keccak"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f6d5ed8676d904364de097082f4e7d240b571b67989ced0240f08b7f966f940"
+dependencies = [
+ "cpufeatures",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.144"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b00cc1c228a6782d0f076e7b232802e0c5689d41bb5df366f2a6b6621cfdfe1"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.58"
@@ -64,6 +135,27 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82e6b795fe2e3b1e845bafcb27aa35405c4d47cdfc92af5fc8d3002f76cebdc0"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
+[[package]]
+name = "sha3"
+version = "0.10.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75872d278a8f37ef87fa0ddbda7802605cb18344497949862c0d4dcb291eba60"
+dependencies = [
+ "digest",
+ "keccak",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.16"
@@ -75,8 +167,20 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "497961ef93d974e23eb6f433eb5fe1b7930b659f06d12dec6fc44a8f554c0bba"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5464a87b239f13a63a501f2701565754bae92d243d4bb7eb12f6d57d2269bf4"
+
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
diff --git a/Cargo.toml b/Cargo.toml
index 7ed66c9..b285aee 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,4 +9,5 @@ edition = "2021"
 bincode = "1.3.3"
 serde = { version = "1.0.163", features = ["derive"] }
 byteorder = "1.4.3"
-
+sha3 = "0.10.8"
+sha2 = "0.10.6"
diff --git a/generate_data.py b/generate_data.py
index 166acca..c9f02f4 100644
--- a/generate_data.py
+++ b/generate_data.py
@@ -1,6 +1,6 @@
 import secrets
 
-rndsize = 488*2
+rndsize = 488*100+5
 
 rndbytes = secrets.token_bytes(rndsize)
 
diff --git a/server.py b/server.py
index 36b6234..3146ed4 100644
--- a/server.py
+++ b/server.py
@@ -1,6 +1,6 @@
 import socket, struct, os, select, math, hashlib, re#, brotli
 
-max_frame_payload=1016 #508 is the minimum size for routers to "understand" udp packets, but we can possibly send more data
+max_frame_payload=508 #1016 #508 is the minimum size for routers to "understand" udp packets, but we can possibly send more data
 header = "!L16s"
 header_size = struct.calcsize(header)
 max_payload = max_frame_payload - header_size
diff --git a/src/big_array.rs b/src/big_array.rs
new file mode 100644
index 0000000..f586968
--- /dev/null
+++ b/src/big_array.rs
@@ -0,0 +1,68 @@
+use std::fmt;
+use std::marker::PhantomData;
+use serde::ser::{Serialize, Serializer, SerializeTuple};
+use serde::de::{Deserialize, Deserializer, Visitor, SeqAccess, Error};
+
+pub trait BigArray<'de>: Sized {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: Serializer;
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where D: Deserializer<'de>;
+}
+
+macro_rules! big_array {
+    ($($len:expr,)+) => {
+        $(
+            impl<'de, T> BigArray<'de> for [T; $len]
+                where T: Default + Copy + Serialize + Deserialize<'de>
+            {
+                fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+                    where S: Serializer
+                {
+                    let mut seq = serializer.serialize_tuple(self.len())?;
+                    for elem in &self[..] {
+                        seq.serialize_element(elem)?;
+                    }
+                    seq.end()
+                }
+
+                fn deserialize<D>(deserializer: D) -> Result<[T; $len], D::Error>
+                    where D: Deserializer<'de>
+                {
+                    struct ArrayVisitor<T> {
+                        element: PhantomData<T>,
+                    }
+
+                    impl<'de, T> Visitor<'de> for ArrayVisitor<T>
+                        where T: Default + Copy + Deserialize<'de>
+                    {
+                        type Value = [T; $len];
+
+                        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                            formatter.write_str(concat!("an array of length ", $len))
+                        }
+
+                        fn visit_seq<A>(self, mut seq: A) -> Result<[T; $len], A::Error>
+                            where A: SeqAccess<'de>
+                        {
+                            let mut arr = [T::default(); $len];
+                            for i in 0..$len {
+                                arr[i] = seq.next_element()?
+                                    .ok_or_else(|| Error::invalid_length(i, &self))?;
+                            }
+                            Ok(arr)
+                        }
+                    }
+
+                    let visitor = ArrayVisitor { element: PhantomData };
+                    deserializer.deserialize_tuple($len, visitor)
+                }
+            }
+        )+
+    }
+}
+
+big_array! {
+    40, 48, 50, 56, 64, 72, 96, 100, 128, 160, 192, 200, 224, 256, 384, 488, 512,
+    768, 1024, 2048, 4096, 8192, 16384, 32768, 65536,
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index fe94194..132ec5a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,11 @@
 use bincode::{self, Error, options, Options};
-use std::net::{UdpSocket, SocketAddr};
+use std::{net::{UdpSocket, SocketAddr}, io::Write};
 use serde::{Serialize, Deserialize};
+use sha3::{Digest, Sha3_512};
+use sha2::Sha512;
+
+mod big_array;
+use big_array::BigArray;
 
 const MAX_FRAME_PAYLOAD:u16=508;
 const MAX_FRAME_PAYLOAD_U:usize=MAX_FRAME_PAYLOAD as usize;
@@ -15,10 +20,12 @@ struct PacketInformation {
     response_filename_checksum: u64, //8 bytes
 } //14 bytes
 
-struct packet {
+#[derive(Serialize, Deserialize)]
+struct Packet {
     packet_number: u32, //4 bytes
-    payload_hash: u128, //16 bytes
-    payload: [u8; MAX_PAYLOAD_U], //508 bytes
+    payload_hash: [u8; 16], //16 bytes
+    #[serde(with = "BigArray")]
+    payload: [u8; MAX_PAYLOAD_U], //488 bytes
 } //512 bytes
 
 fn main() {
@@ -28,8 +35,8 @@ fn main() {
 
     let filename = "data.bin";
 
-    let local_addr: SocketAddr = "0.0.0.0:26000".parse().expect("Failed to parse address");
-    let socket = UdpSocket::bind(local_addr).expect("Failed to bind socket");
+    let local_addr: SocketAddr = "0.0.0.0:0".parse().expect("Failed to parse address");
+    let socket = UdpSocket::bind(local_addr).expect("Failed to bind socket to port 26000");
 
     socket.set_read_timeout(Some(std::time::Duration::new(timeout, 0))).expect("set_read_timeout call failed");
     //socket.set_nonblocking(true).expect("set_nonblocking call failed");
@@ -74,28 +81,137 @@ fn main() {
     }
 
     //create vector to store the packets
-    let mut packets: Vec<u8> = Vec::new();
+    let mut packets: Vec<Vec<u8>> = Vec::new();
     for _ in 0..packet_info.packet_numbers {
-        packets.push(0);
+        packets.push(Vec::new());
     }
 
-    let received_packets = 0;
+    let mut received_packets = 0;
+
+    let mut server_hash = [0u8; 64];
+    let mut server_hash_received = false;
 
     //receive the packets
-    while received_packets < packet_info.packet_numbers {
-        let mut buffer = [0u8; MAX_PAYLOAD_U];
-        let (received_bytes, remote_addr) = socket.recv_from(&mut buffer).expect("Failed to receive data");
+    while received_packets < packet_info.packet_numbers-1 || !server_hash_received {
+        let mut buffer = [0u8; MAX_FRAME_PAYLOAD_U];
+        let res = socket.recv_from(&mut buffer);
+        if let Ok((received_bytes, remote_addr)) = res {
+            let filled_buffer = &buffer;//[..received_bytes];
 
-        let filled_buffer = &buffer[..received_bytes];
+            //print the filled buffer
+            //println!("Received data: {:?} {}", filled_buffer, filled_buffer.len());
 
-        //print the filled buffer
-        println!("Received data: {:?} {}", filled_buffer, filled_buffer.len());
+            if remote_addr != server_addr {
+                panic!("Received data from unknown address");
+            }
 
-        if remote_addr != server_addr {
-            panic!("Received data from unknown address");
+            if received_bytes == 65 {
+                //println!("Received hash packet, ignoring for now");
+                server_hash = filled_buffer[0..64].try_into().expect("Failed to convert hash");
+                //println!("Received hash: {:?}", server_hash);
+                server_hash_received = true;
+                continue;
+            }
+
+            if received_bytes != MAX_FRAME_PAYLOAD_U {
+                println!("Received packet with invalid size {} not {} | ignoring", received_bytes, MAX_FRAME_PAYLOAD_U);
+                continue;
+            }
+
+            let packet_result: Result<Packet, Error> = options.deserialize(filled_buffer);
+            let packet: Packet;
+            match packet_result {
+                Ok(p) => {
+                    //println!("Packet {}", p.packet_number);
+                    //check checksum with sum
+                    if p.packet_number != packet_info.packet_numbers - 1 {
+                        let mut hasher = Sha3_512::new();
+                        hasher.update(&p.payload);
+                        let hash = hasher.finalize();
+
+                        if p.payload_hash != hash[..16] {
+                            continue;
+                        }
+
+                        packet = p;
+                    } else {
+                        //cut packet down to size
+                        packets[p.packet_number as usize] = p.payload[..packet_info.last_packet_size as usize].to_vec();
+                        continue;
+                    }
+                }
+                Err(err) => {
+                    panic!("Failed to deserialize data: {}", err);
+                }
+            }
+
+            if packets[packet.packet_number as usize].len() != 0 {
+                //println!("Packet already received, ignoring");
+                continue;
+            }
+
+            packets[packet.packet_number as usize] = packet.payload.to_vec();
+            received_packets += 1;
+        } else {
+            //println!("Timeout, requesting again {}/{}\r", received_packets, packet_info.packet_numbers);
+            //collect packets that were not received and send them in n messages
+            //where n is the minimum amount of messages needed to request all packets
+            let mut missing_packets: Vec<u32> = Vec::new();
+            for i in 0..packet_info.packet_numbers {
+                if packets[i as usize].len() == 0 {
+                    missing_packets.push(i);
+                }
+            }
+
+            //split lost_packets into groups of size 508-filename.len() bytes
+            let mut missing_packet_groups: Vec<String> = Vec::new();
+            let mut current_group: String = filename.to_string();
+            for i in 0..missing_packets.len() {
+                if current_group.len() + missing_packets[i].to_string().len() + 1 > MAX_PAYLOAD_U {
+                    missing_packet_groups.push(current_group);
+                    current_group = filename.to_string();
+                }
+                current_group.push('/');
+                current_group.push_str(&missing_packets[i].to_string());
+            }
+
+            if current_group.len() > filename.len() {
+                missing_packet_groups.push(current_group);
+            }
+
+            for i in 0..missing_packet_groups.len() {
+                let message = &missing_packet_groups[i];
+                //println!("Requesting packets: {}", message);
+                socket.send_to(message.as_bytes(), server_addr).expect("Failed to send data");
+            }
+
+            if !server_hash_received {
+                let message = filename.to_string()+":";
+                socket.send_to(message.as_bytes(), server_addr).expect("Failed to send data");
+            }
         }
 
-        
+        print!("Packet {}/{}\r", received_packets, packet_info.packet_numbers);
+    }
+
+    //check hash via sha512
+
+    let mut hasher = Sha512::new();
+    for i in 0..packets.len() {
+        hasher.update(&packets[i]);
+    }
+    let client_hash = hasher.finalize();
+
+    if client_hash[..64] != server_hash {
+        panic!("Hashes do not match, correct hash: {:?}, client hash: {:?}", server_hash, client_hash);
+    }
+
+
+    println!("Received all packets, writing to file");
+    //write packets to file
+    let mut file = std::fs::File::create("received/".to_string()+filename).expect("Failed to create file");
+    for i in 0..packets.len() {
+        file.write_all(&packets[i]).expect("Failed to write to file");
     }
 
 }