diff --git a/src/ironforce.rs b/src/ironforce.rs
index 2f7ed9c..f5f4ad8 100644
--- a/src/ironforce.rs
+++ b/src/ironforce.rs
@@ -1,3 +1,5 @@
-pub struct IronForce {
+use crate::transport::Transport;
 
+pub struct IronForce {
+    transport: Transport
 }
diff --git a/src/lib.rs b/src/lib.rs
index 2cafc3d..56859e4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,7 @@ mod transport;
 mod interface;
 mod interfaces;
 mod res;
+mod tunnel;
 
 #[cfg(test)]
 mod tests {
diff --git a/src/message.rs b/src/message.rs
index ffd4ef2..359a961 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -1,5 +1,79 @@
 use alloc::vec::Vec;
+use crate::crypto::{Keys, PublicKey};
+use crate::res::IFResult;
+use crate::tunnel::TunnelPublic;
 
 
 /// A serialized message
 pub(crate) type MessageBytes = Vec<u8>;
+
+
+pub enum Signature {
+    /// The message is signed. Author is unknown
+    NotSigned,
+    /// The message is signed with the sender's key visible to everyone
+    Signed {
+        sender: PublicKey,
+        signature: Vec<u8>,
+    },
+    /// Sender's key is encrypted for the recipient
+    SignedPrivately {
+        sender_encrypted: Vec<u8>,
+        signature: Vec<u8>,
+    }
+}
+
+pub enum MessageType {
+    SingleCast,
+    Broadcast,
+    Service(ServiceMessageType),
+}
+
+pub enum ServiceMessageType {
+    TunnelBuilding(TunnelPublic)
+}
+
+pub enum MessageContent {
+    /// Just plaintext message content
+    Plain(Vec<u8>),
+    /// Message content bytes encrypted for the recipient
+    Encrypted(Vec<u8>),
+}
+
+pub struct Message {
+    /// Content of the message (not to be confused with the bytes that we are sending through interfaces)
+    content: MessageContent,
+    /// The type of this message
+    message_type: MessageType,
+    /// Sender's signature
+    signature: Signature,
+    /// A random number that is used in hash together with the content
+    salt: u64,
+    /// Hash of message content and the salt
+    hash: Vec<u8>,
+    /// Optional: hash of the message encrypted for the recipient, so that the recipient can know that this message is for them, but nobody else
+    recipient_verification: Option<Vec<u8>>,
+    /// ID of the tunnel that is used
+    tunnel_id: u64,
+}
+
+impl Message {
+    /// Verify message's hash
+    pub fn verify(&self) -> bool {
+        todo!()
+    }
+
+    /// Check if this message is for this set of keys
+    pub fn check_recipient(&self, _keys: Keys) -> bool {
+        todo!()
+    }
+
+    /// Get decrypted content of the message
+    pub fn get_decrypted(&self, _keys: Keys) -> IFResult<Vec<u8>> {
+        todo!()
+    }
+
+    pub fn calculate_hash(_content: MessageContent, _message_type: MessageType, _sender: Option<PublicKey>) -> Vec<u8> {
+        todo!()
+    }
+}
diff --git a/src/tunnel.rs b/src/tunnel.rs
new file mode 100644
index 0000000..ac44110
--- /dev/null
+++ b/src/tunnel.rs
@@ -0,0 +1,30 @@
+use alloc::vec::Vec;
+use crate::crypto::PublicKey;
+
+/// A tunnel that is used for communication
+pub struct Tunnel {
+    /// Tunnel's id
+    id: Option<u64>,
+    /// Ids that are
+    local_ids: Vec<u64>,
+    /// Ids of peers (in transport) by which we can send a message - one for backward direction, another for forward
+    peer_ids: (u64, u64),
+    /// Time at which this tunnel should be destroyed (UNIX epoch)
+    ttd: u64,
+    /// Public keys of nodes
+    nodes_in_tunnel: Option<Vec<PublicKey>>,
+    /// Is this tunnel used for multicast?
+    is_multicast: bool,
+}
+
+/// Tunnel, but only the fields that are ok to share
+pub struct TunnelPublic {
+    /// Tunnel's id
+    id: Option<u64>,
+    /// Ids that are
+    local_ids: Vec<u64>,
+    /// Time at which this tunnel should be destroyed (UNIX epoch)
+    ttd: u64,
+    /// Public keys of nodes
+    nodes_in_tunnel: Option<Vec<PublicKey>>,
+}