diff --git a/src/api/mod.rs b/src/api/mod.rs
index 5b2ef75..e736ca5 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -6,9 +6,10 @@ use log::info;
 mod endpoints;
 
 pub async fn start(config: &Config, backend: Backend) -> Result<()> {
+    let data = web::Data::new(backend);
     let server = HttpServer::new(move || {
         App::new()
-            .app_data(web::Data::new(backend.clone()))
+            .app_data(data.clone())
             .service(endpoints::account::register)
             .service(endpoints::account::auth)
             .service(endpoints::account::invite::new)
diff --git a/src/backend/db_structures.rs b/src/backend/db_structures.rs
index 764d029..40281c7 100644
--- a/src/backend/db_structures.rs
+++ b/src/backend/db_structures.rs
@@ -16,3 +16,15 @@ pub struct UsersRow {
     pub password: String,
     pub permissions: u16,
 }
+
+pub struct RelaysRow {
+    pub id: String,
+    pub secret: String,
+}
+
+pub struct RelayIndexRow {
+    pub public_id: String,
+    pub public_key: [u8; 32],
+    pub auth: String,
+    pub name: String,
+}
diff --git a/src/backend/error.rs b/src/backend/error.rs
index 5537804..0e71043 100644
--- a/src/backend/error.rs
+++ b/src/backend/error.rs
@@ -13,6 +13,9 @@ pub enum Error {
     #[error("Permission denied: {0}")]
     PermissionDenied(&'static str),
 
+    #[error("The given relay id cannot be mapped to a relay")]
+    RelayNotFound,
+
     #[error("The given token is expired")]
     TokenExpired,
 
@@ -37,6 +40,7 @@ impl Into<HttpResponse> for Error {
             Error::AuthenticationFailure => HttpResponse::Unauthorized().json(body),
             Error::InvalidToken => HttpResponse::Unauthorized().json(body),
             Error::PermissionDenied(_) => HttpResponse::Forbidden().json(body),
+            Error::RelayNotFound => HttpResponse::NotFound().json(body),
             Error::TokenExpired => HttpResponse::Gone().json(body),
             Error::UserNotFound => HttpResponse::NotFound().json(body),
         }
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index ed1ecbd..99e872f 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -5,14 +5,17 @@ mod relay;
 mod tokens;
 mod user;
 
-use crate::config::Config;
+use crate::{backend::relay::Relay, config::Config};
 use anyhow::Result;
 use log::info;
 use sqlx::MySqlPool;
+use std::collections::HashMap;
+use uuid::Uuid;
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct Backend {
     pub pool: MySqlPool,
+    pub relays: HashMap<Uuid, Relay>,
 }
 
 impl Backend {
@@ -59,6 +62,9 @@ impl Backend {
 
         info!("Backend initialized");
 
-        Ok(Self { pool })
+        Ok(Self {
+            pool,
+            relays: HashMap::new(),
+        })
     }
 }
diff --git a/src/backend/relay.rs b/src/backend/relay.rs
index 4fb02b6..9ec4545 100644
--- a/src/backend/relay.rs
+++ b/src/backend/relay.rs
@@ -1,11 +1,37 @@
-use crate::backend::{error::Error, user::IntoUser, Backend};
+use crate::backend::{
+    db_structures::{RelayIndexRow, RelaysRow},
+    error::Error,
+    user::IntoUser,
+    Backend,
+};
+use anyhow::{bail, Result};
 use argon2::{
     password_hash::{rand_core::OsRng, PasswordHasher, SaltString},
     Argon2,
 };
 use rand::distributions::DistString;
+use std::collections::{HashMap, VecDeque};
 use uuid::Uuid;
 
+#[derive(Debug)]
+struct EncryptedMessage {
+    sender: Uuid,
+    body: Vec<u8>,
+}
+
+#[derive(Debug)]
+struct UserIndex {
+    public_key: [u8; 32],
+    name: String,
+    messages: VecDeque<EncryptedMessage>,
+}
+
+#[derive(Debug)]
+pub struct Relay {
+    user_index: HashMap<Uuid, UserIndex>,
+    user_map: HashMap<Uuid, Uuid>,
+}
+
 impl Backend {
     /// Creates the structures for a new relay
     pub async fn create_relay(
@@ -38,7 +64,7 @@ impl Backend {
         sqlx::query(&format!(
             "CREATE TABLE RelayIndex_{} (
                 public_id   UUID            NOT NULL    PRIMARY KEY,
-                public_key  BLOB(4096)      NOT NULL,
+                public_key  BINARY(32)      NOT NULL,
                 auth        VARCHAR(128)    NOT NULL,
                 name        VARCHAR(32)
             );",
@@ -49,4 +75,36 @@ impl Backend {
 
         Ok(Ok((relay_id, secret)))
     }
+
+    pub async fn get_relay(&mut self, relay_id: Uuid) -> Result<Result<&Relay, Error>> {
+        // can't use early return pattern, because of the borrow checker :/
+        if self.relays.get(&relay_id).is_none() {
+            match sqlx::query_as!(
+                RelaysRow,
+                r#"SELECT * FROM Relays WHERE id = ? LIMIT 1;"#,
+                relay_id.as_bytes().as_slice()
+            )
+            .fetch_one(&self.pool)
+            .await
+            {
+                Err(sqlx::Error::RowNotFound) => return Ok(Err(Error::RelayNotFound)),
+                Err(e) => return Err(e.into()),
+                Ok(_) => {
+                    // the hashmaps will be filled, as soon, as clients subscribe to the relay
+                    let relay = Relay {
+                        user_index: HashMap::new(),
+                        user_map: HashMap::new(),
+                    };
+
+                    self.relays.insert(relay_id, relay);
+                }
+            }
+        }
+
+        if let Some(relay) = self.relays.get(&relay_id) {
+            Ok(Ok(relay))
+        } else {
+            bail!("!!! This should never happen !!! relay not found in runtime manager, even tho it was there before.")
+        }
+    }
 }