diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..96ef6c0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/target
+Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..5e2afac
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,24 @@
+[package]
+name = "rb-common"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+# Backend web framework
+rocket = { version = "0.5.0-rc.1", features = [ "json", "uuid" ] }
+# Used to (de)serialize JSON
+serde = { version = "1.0.127", features = [ "derive" ] }
+rand = "0.8.4"
+uuid = { version = "0.8.2", features = ["serde"] }
+# Authentification
+jwt = "0.14.0"
+hmac = "*"
+sha2 = "*"
+# Timestamps for JWT tokens
+chrono = { version = "*", features = [ "serde" ] }
+# Encoding of refresh tokens
+base64 = "0.13.0"
+# Reading in configuration files
+figment = { version = "*", features = [ "yaml" ] }
diff --git a/src/auth/jwt.rs b/src/auth/jwt.rs
new file mode 100644
index 0000000..d9cf108
--- /dev/null
+++ b/src/auth/jwt.rs
@@ -0,0 +1,103 @@
+use chrono::Utc;
+use hmac::{Hmac, NewMac};
+use jwt::SignWithKey;
+use rand::{thread_rng, Rng};
+use serde::{Deserialize, Serialize};
+use sha2::Sha256;
+
+use crate::{
+    errors::{RbError, RbResult},
+    RbJwtConf,
+};
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct JWTResponse {
+    token: String,
+    refresh_token: String,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Claims {
+    pub id: uuid::Uuid,
+    pub username: String,
+    pub admin: bool,
+    pub exp: i64,
+}
+
+pub fn generate_jwt_token(
+    jwt: &RbJwtConf,
+    id: uuid::Uuid,
+    username: String,
+    is_admin: bool,
+) -> RbResult<JWTResponse> {
+    let key: Hmac<Sha256> = Hmac::new_from_slice(jwt.key.as_bytes())
+        .map_err(|_| RbError::Custom("Couldn't create Hmac key."))?;
+
+    let current_time = Utc::now();
+
+    // Create the claims
+    let claims = Claims {
+        id,
+        username: username.clone(),
+        admin: is_admin,
+        exp: current_time.timestamp() + jwt.refresh_token_expire,
+    };
+
+    // Sign the claims into a new token
+    let token = claims
+        .sign_with_key(&key)
+        .map_err(|_| RbError::Custom("Couldn't sign JWT."))?;
+
+    // Generate a random refresh token
+    let mut refresh_token = vec![0u8; jwt.refresh_token_size];
+    thread_rng().fill(&mut refresh_token[..]);
+
+    let refresh_expire =
+        (current_time + chrono::Duration::seconds(jwt.refresh_token_expire)).naive_utc();
+
+    Ok(JWTResponse {
+        token,
+        refresh_token: base64::encode(refresh_token),
+    })
+}
+
+pub fn refresh_token(
+    conn: &PgConnection,
+    jwt: &RbJwtConf,
+    refresh_token: &str,
+) -> RbResult<JWTResponse> {
+    let token_bytes =
+        base64::decode(refresh_token).map_err(|_| RbError::AuthInvalidRefreshToken)?;
+
+    // First, we request the token from the database to see if it's really a valid token
+    let (token_entry, user) =
+        db::tokens::find_with_user(conn, &token_bytes).ok_or(RbError::AuthInvalidRefreshToken)?;
+
+    // If we see that the token has already been used before, we block the user.
+    if token_entry.last_used_at.is_some() {
+        // If we fail to block the user, the end user must know
+        if let Err(err) = db::users::block(conn, token_entry.user_id) {
+            return Err(err);
+        }
+
+        return Err(RbError::AuthDuplicateRefreshToken);
+    }
+
+    // Then we check if the user is blocked
+    if user.blocked {
+        return Err(RbError::AuthBlockedUser);
+    }
+
+    // Now we check if the token has already expired
+    let cur_time = Utc::now().naive_utc();
+
+    if token_entry.expires_at < cur_time {
+        return Err(RbError::AuthTokenExpired);
+    }
+
+    // We update the last_used_at value for the refresh token
+    db::tokens::update_last_used_at(conn, &token_entry.token, cur_time)?;
+
+    generate_jwt_token(conn, jwt, &user)
+}
diff --git a/src/auth/mod.rs b/src/auth/mod.rs
new file mode 100644
index 0000000..417233c
--- /dev/null
+++ b/src/auth/mod.rs
@@ -0,0 +1 @@
+pub mod jwt;
diff --git a/src/errors.rs b/src/errors.rs
new file mode 100644
index 0000000..561fef7
--- /dev/null
+++ b/src/errors.rs
@@ -0,0 +1,94 @@
+use rocket::{
+    http::Status,
+    request::Request,
+    response::{self, Responder},
+    serde::json::json,
+};
+
+#[derive(Debug)]
+pub enum RbError
+{
+    AuthUnknownUser,
+    AuthBlockedUser,
+    AuthInvalidPassword,
+    AuthUnauthorized,
+    AuthTokenExpired,
+    AuthRefreshTokenExpired,
+    AuthInvalidRefreshToken,
+    AuthDuplicateRefreshToken,
+    AuthMissingHeader,
+
+    // UM = User Management
+    UMDuplicateUser,
+    UMUnknownUser,
+
+    DbError(&'static str),
+    Custom(&'static str),
+}
+
+impl RbError
+{
+    pub fn status(&self) -> Status
+    {
+        // Every entry gets its own line for easy editing later when needed
+        match self {
+            RbError::AuthUnknownUser => Status::NotFound,
+            RbError::AuthBlockedUser => Status::Forbidden,
+            RbError::AuthInvalidPassword => Status::Unauthorized,
+            RbError::AuthUnauthorized => Status::Unauthorized,
+            RbError::AuthTokenExpired => Status::Unauthorized,
+            RbError::AuthRefreshTokenExpired => Status::Unauthorized,
+            RbError::AuthInvalidRefreshToken => Status::Unauthorized,
+            RbError::AuthDuplicateRefreshToken => Status::Unauthorized,
+            RbError::AuthMissingHeader => Status::BadRequest,
+
+            RbError::UMDuplicateUser => Status::Conflict,
+
+            RbError::Custom(_) => Status::InternalServerError,
+            _ => Status::InternalServerError,
+        }
+    }
+
+    pub fn message(&self) -> &'static str
+    {
+        match self {
+            RbError::AuthUnknownUser => "This user doesn't exist.",
+            RbError::AuthBlockedUser => "This user is blocked.",
+            RbError::AuthInvalidPassword => "Invalid credentials.",
+            RbError::AuthUnauthorized => "You are not authorized to access this resource.",
+            RbError::AuthTokenExpired => "This token is not valid anymore.",
+            RbError::AuthRefreshTokenExpired => "This refresh token is not valid anymore.",
+            RbError::AuthInvalidRefreshToken => "This refresh token is not valid.",
+            RbError::AuthDuplicateRefreshToken => {
+                "This refresh token has already been used. The user has been blocked."
+            },
+            RbError::AuthMissingHeader => "Missing Authorization header.",
+
+            RbError::UMDuplicateUser => "This user already exists.",
+
+            RbError::Custom(message) => message,
+            _ => "",
+        }
+    }
+}
+
+impl<'r> Responder<'r, 'static> for RbError
+{
+    fn respond_to(self, req: &'r Request<'_>) -> response::Result<'static>
+    {
+        let status = self.status();
+        let content = json!({
+            "status": status.code,
+            "message": self.message(),
+        });
+
+        // TODO add status to response
+        content.respond_to(req)
+    }
+}
+
+/// Type alias for results that can return an RbError
+pub type RbResult<T> = std::result::Result<T, RbError>;
+
+/// Type alias for optional results that can fail & return an RbError
+pub type RbOption<T> = RbResult<Option<T>>;
diff --git a/src/guards.rs b/src/guards.rs
new file mode 100644
index 0000000..1ecd436
--- /dev/null
+++ b/src/guards.rs
@@ -0,0 +1,115 @@
+use hmac::{Hmac, NewMac};
+use jwt::VerifyWithKey;
+use rocket::{
+    http::Status,
+    outcome::try_outcome,
+    request::{FromRequest, Outcome, Request},
+    State,
+};
+use sha2::Sha256;
+
+use crate::{auth::jwt::Claims, errors::RbError, RbConfig};
+
+/// Extracts an "Authorization: Bearer" string from the headers.
+pub struct Bearer<'a>(&'a str);
+
+#[rocket::async_trait]
+impl<'r> FromRequest<'r> for Bearer<'r>
+{
+    type Error = crate::errors::RbError;
+
+    async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error>
+    {
+        // If the header isn't present, just forward to the next route
+        let header = match req.headers().get_one("Authorization") {
+            None => return Outcome::Forward(()),
+            Some(val) => val,
+        };
+
+        if header.starts_with("Bearer ") {
+            match header.get(7..) {
+                Some(s) => Outcome::Success(Self(s)),
+                None => Outcome::Failure((Status::Unauthorized, Self::Error::AuthUnauthorized)),
+            }
+        } else {
+            Outcome::Forward(())
+        }
+    }
+}
+
+/// Verifies the provided JWT is valid.
+pub struct Jwt(Claims);
+
+#[rocket::async_trait]
+impl<'r> FromRequest<'r> for Jwt
+{
+    type Error = RbError;
+
+    async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error>
+    {
+        let bearer = try_outcome!(req.guard::<Bearer>().await).0;
+        let config = try_outcome!(req.guard::<&State<RbConfig>>().await.map_failure(|_| (
+            Status::InternalServerError,
+            RbError::Custom("Couldn't get config guard.")
+        )));
+
+        let key: Hmac<Sha256> = match Hmac::new_from_slice(&config.jwt.key.as_bytes()) {
+            Ok(key) => key,
+            Err(_) => {
+                return Outcome::Failure((
+                    Status::InternalServerError,
+                    Self::Error::Custom("Failed to do Hmac thing."),
+                ))
+            },
+        };
+
+        // Verify token using key
+        match bearer.verify_with_key(&key) {
+            Ok(claims) => Outcome::Success(Self(claims)),
+            Err(_) => {
+                return Outcome::Failure((Status::Unauthorized, Self::Error::AuthUnauthorized))
+            },
+        }
+    }
+}
+
+/// Verifies the JWT has not expired.
+pub struct User(Claims);
+
+#[rocket::async_trait]
+impl<'r> FromRequest<'r> for User
+{
+    type Error = crate::errors::RbError;
+
+    async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error>
+    {
+        let claims = try_outcome!(req.guard::<Jwt>().await).0;
+
+        // Verify key hasn't yet expired
+        if chrono::Utc::now().timestamp() > claims.exp {
+            Outcome::Failure((Status::Forbidden, Self::Error::AuthTokenExpired))
+        } else {
+            Outcome::Success(Self(claims))
+        }
+    }
+}
+
+/// Verifies the JWT belongs to an admin.
+pub struct Admin(Claims);
+
+#[rocket::async_trait]
+impl<'r> FromRequest<'r> for Admin
+{
+    type Error = crate::errors::RbError;
+
+    async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error>
+    {
+        let user = try_outcome!(req.guard::<User>().await).0;
+
+        if user.admin {
+            Outcome::Success(Self(user))
+        } else {
+            Outcome::Failure((Status::Unauthorized, RbError::AuthUnauthorized))
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..f34c28a
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,3 @@
+pub mod auth;
+pub mod errors;
+pub mod guards;