diff --git a/src/accountant.rs b/src/accountant.rs
index 2892c39737..ab2e3adc8f 100644
--- a/src/accountant.rs
+++ b/src/accountant.rs
@@ -2,7 +2,7 @@
 //! event log to record transactions. Its users can deposit funds and
 //! transfer funds to other users.
 
-use log::{Event, PublicKey, Sha256Hash, Signature};
+use log::{Entry, Event, PublicKey, Sha256Hash, Signature};
 use historian::Historian;
 use ring::signature::Ed25519KeyPair;
 use std::sync::mpsc::{RecvError, SendError};
@@ -11,6 +11,7 @@ use std::collections::HashMap;
 pub struct Accountant {
     pub historian: Historian<u64>,
     pub balances: HashMap<PublicKey, u64>,
+    pub signatures: HashMap<Signature, bool>,
     pub end_hash: Sha256Hash,
 }
 
@@ -20,13 +21,19 @@ impl Accountant {
         Accountant {
             historian: hist,
             balances: HashMap::new(),
+            signatures: HashMap::new(),
             end_hash: *start_hash,
         }
     }
 
     pub fn process_event(self: &mut Self, event: &Event<u64>) {
         match *event {
-            Event::Claim { key, data, .. } => {
+            Event::Claim { key, data, sig } => {
+                if self.signatures.contains_key(&sig) {
+                    return;
+                }
+                self.signatures.insert(sig, true);
+
                 if self.balances.contains_key(&key) {
                     if let Some(x) = self.balances.get_mut(&key) {
                         *x += data;
@@ -35,7 +42,16 @@ impl Accountant {
                     self.balances.insert(key, data);
                 }
             }
-            Event::Transaction { from, to, data, .. } => {
+            Event::Transaction {
+                from,
+                to,
+                data,
+                sig,
+            } => {
+                if self.signatures.contains_key(&sig) {
+                    return;
+                }
+                self.signatures.insert(sig, true);
                 if let Some(x) = self.balances.get_mut(&from) {
                     *x -= data;
                 }
@@ -51,7 +67,7 @@ impl Accountant {
         }
     }
 
-    pub fn sync(self: &mut Self) {
+    pub fn sync(self: &mut Self) -> Vec<Entry<u64>> {
         let mut entries = vec![];
         while let Ok(entry) = self.historian.receiver.try_recv() {
             entries.push(entry);
@@ -67,6 +83,8 @@ impl Accountant {
         for e in &entries {
             self.process_event(&e.event);
         }
+
+        entries
     }
 
     pub fn deposit_signed(
@@ -83,11 +101,11 @@ impl Accountant {
         self: &Self,
         n: u64,
         keypair: &Ed25519KeyPair,
-    ) -> Result<(), SendError<Event<u64>>> {
+    ) -> Result<Signature, SendError<Event<u64>>> {
         use log::{get_pubkey, sign_serialized};
         let key = get_pubkey(keypair);
         let sig = sign_serialized(&n, keypair);
-        self.deposit_signed(key, n, sig)
+        self.deposit_signed(key, n, sig).map(|_| sig)
     }
 
     pub fn transfer_signed(
@@ -116,25 +134,41 @@ impl Accountant {
         n: u64,
         keypair: &Ed25519KeyPair,
         to: PublicKey,
-    ) -> Result<(), SendError<Event<u64>>> {
+    ) -> Result<Signature, SendError<Event<u64>>> {
         use log::{get_pubkey, sign_transaction_data};
 
         let from = get_pubkey(keypair);
         let sig = sign_transaction_data(&n, keypair, &to);
-        self.transfer_signed(from, to, n, sig)
+        self.transfer_signed(from, to, n, sig).map(|_| sig)
     }
 
     pub fn get_balance(self: &mut Self, pubkey: &PublicKey) -> Result<u64, RecvError> {
         self.sync();
         Ok(*self.balances.get(pubkey).unwrap_or(&0))
     }
+
+    pub fn wait_on_signature(self: &mut Self, wait_sig: &Signature) {
+        use std::thread::sleep;
+        use std::time::Duration;
+        let mut entries = self.sync();
+        let mut found = false;
+        while !found {
+            found = entries.iter().any(|e| match e.event {
+                Event::Claim { sig, .. } => sig == *wait_sig,
+                Event::Transaction { sig, .. } => sig == *wait_sig,
+                _ => false,
+            });
+            if !found {
+                sleep(Duration::from_millis(30));
+                entries = self.sync();
+            }
+        }
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::thread::sleep;
-    use std::time::Duration;
     use log::{generate_keypair, get_pubkey};
     use historian::ExitReason;
 
@@ -145,13 +179,13 @@ mod tests {
         let alice_keypair = generate_keypair();
         let bob_keypair = generate_keypair();
         acc.deposit(10_000, &alice_keypair).unwrap();
-        acc.deposit(1_000, &bob_keypair).unwrap();
+        let sig = acc.deposit(1_000, &bob_keypair).unwrap();
+        acc.wait_on_signature(&sig);
 
-        sleep(Duration::from_millis(30));
         let bob_pubkey = get_pubkey(&bob_keypair);
-        acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
+        let sig = acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
+        acc.wait_on_signature(&sig);
 
-        sleep(Duration::from_millis(30));
         assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_500);
 
         drop(acc.historian.sender);
@@ -163,18 +197,20 @@ mod tests {
 
     #[test]
     fn test_invalid_transfer() {
+        use std::thread::sleep;
+        use std::time::Duration;
         let zero = Sha256Hash::default();
         let mut acc = Accountant::new(&zero, Some(2));
         let alice_keypair = generate_keypair();
         let bob_keypair = generate_keypair();
         acc.deposit(10_000, &alice_keypair).unwrap();
-        acc.deposit(1_000, &bob_keypair).unwrap();
+        let sig = acc.deposit(1_000, &bob_keypair).unwrap();
+        acc.wait_on_signature(&sig);
 
-        sleep(Duration::from_millis(30));
         let bob_pubkey = get_pubkey(&bob_keypair);
         acc.transfer(10_001, &alice_keypair, bob_pubkey).unwrap();
-
         sleep(Duration::from_millis(30));
+
         let alice_pubkey = get_pubkey(&alice_keypair);
         assert_eq!(acc.get_balance(&alice_pubkey).unwrap(), 10_000);
         assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_000);
@@ -192,10 +228,10 @@ mod tests {
         let mut acc = Accountant::new(&zero, Some(2));
         let keypair = generate_keypair();
         acc.deposit(1, &keypair).unwrap();
-        acc.deposit(2, &keypair).unwrap();
+        let sig = acc.deposit(2, &keypair).unwrap();
+        acc.wait_on_signature(&sig);
 
         let pubkey = get_pubkey(&keypair);
-        sleep(Duration::from_millis(30));
         assert_eq!(acc.get_balance(&pubkey).unwrap(), 3);
 
         drop(acc.historian.sender);
@@ -211,13 +247,12 @@ mod tests {
         let mut acc = Accountant::new(&zero, Some(2));
         let alice_keypair = generate_keypair();
         let bob_keypair = generate_keypair();
-        acc.deposit(10_000, &alice_keypair).unwrap();
+        let sig = acc.deposit(10_000, &alice_keypair).unwrap();
+        acc.wait_on_signature(&sig);
 
-        sleep(Duration::from_millis(30));
         let bob_pubkey = get_pubkey(&bob_keypair);
-        acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
-
-        sleep(Duration::from_millis(30));
+        let sig = acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
+        acc.wait_on_signature(&sig);
         assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 500);
 
         drop(acc.historian.sender);
diff --git a/src/accountant_skel.rs b/src/accountant_skel.rs
index 18419896cd..0573299a78 100644
--- a/src/accountant_skel.rs
+++ b/src/accountant_skel.rs
@@ -23,11 +23,15 @@ pub enum Request {
     GetBalance {
         key: PublicKey,
     },
+    Wait {
+        sig: Signature,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub enum Response {
     Balance { key: PublicKey, val: u64 },
+    Confirmed { sig: Signature },
 }
 
 impl AccountantSkel {
@@ -49,26 +53,28 @@ impl AccountantSkel {
                 let val = self.obj.get_balance(&key).unwrap();
                 Some(Response::Balance { key, val })
             }
+            Request::Wait { sig } => {
+                self.obj.wait_on_signature(&sig);
+                Some(Response::Confirmed { sig })
+            }
         }
     }
 
-    /// TCP Server that forwards messages to Accountant methods.
+    /// UDP Server that forwards messages to Accountant methods.
     pub fn serve(self: &mut Self, addr: &str) -> io::Result<()> {
-        use std::net::TcpListener;
-        use std::io::{Read, Write};
+        use std::net::UdpSocket;
         use bincode::{deserialize, serialize};
-        let listener = TcpListener::bind(addr)?;
+        let socket = UdpSocket::bind(addr)?;
         let mut buf = vec![0u8; 1024];
         loop {
-            //println!("skel: Waiting for incoming connections...");
-            let (mut stream, _from_addr) = listener.accept()?;
-            let _sz = stream.read(&mut buf)?;
+            //println!("skel: Waiting for incoming packets...");
+            let (_sz, src) = socket.recv_from(&mut buf)?;
 
             // TODO: Return a descriptive error message if deserialization fails.
             let req = deserialize(&buf).expect("deserialize request");
 
             if let Some(resp) = self.process_request(req) {
-                stream.write(&serialize(&resp).expect("serialize response"))?;
+                socket.send_to(&serialize(&resp).expect("serialize response"), &src)?;
             }
         }
     }
diff --git a/src/accountant_stub.rs b/src/accountant_stub.rs
index 5c5749b1bb..ac1945fa62 100644
--- a/src/accountant_stub.rs
+++ b/src/accountant_stub.rs
@@ -2,9 +2,8 @@
 //! event log to record transactions. Its users can deposit funds and
 //! transfer funds to other users.
 
-use std::net::TcpStream;
+use std::net::UdpSocket;
 use std::io;
-use std::io::{Read, Write};
 use bincode::{deserialize, serialize};
 use log::{PublicKey, Signature};
 use ring::signature::Ed25519KeyPair;
@@ -12,12 +11,14 @@ use accountant_skel::{Request, Response};
 
 pub struct AccountantStub {
     pub addr: String,
+    pub socket: UdpSocket,
 }
 
 impl AccountantStub {
-    pub fn new(addr: &str) -> Self {
+    pub fn new(addr: &str, socket: UdpSocket) -> Self {
         AccountantStub {
             addr: addr.to_string(),
+            socket,
         }
     }
 
@@ -29,15 +30,14 @@ impl AccountantStub {
     ) -> io::Result<usize> {
         let req = Request::Deposit { key, val, sig };
         let data = serialize(&req).unwrap();
-        let mut stream = TcpStream::connect(&self.addr)?;
-        stream.write(&data)
+        self.socket.send_to(&data, &self.addr)
     }
 
-    pub fn deposit(self: &mut Self, n: u64, keypair: &Ed25519KeyPair) -> io::Result<usize> {
+    pub fn deposit(self: &mut Self, n: u64, keypair: &Ed25519KeyPair) -> io::Result<Signature> {
         use log::{get_pubkey, sign_serialized};
         let key = get_pubkey(keypair);
         let sig = sign_serialized(&n, keypair);
-        self.deposit_signed(key, n, sig)
+        self.deposit_signed(key, n, sig).map(|_| sig)
     }
 
     pub fn transfer_signed(
@@ -49,8 +49,7 @@ impl AccountantStub {
     ) -> io::Result<usize> {
         let req = Request::Transfer { from, to, val, sig };
         let data = serialize(&req).unwrap();
-        let mut stream = TcpStream::connect(&self.addr)?;
-        stream.write(&data)
+        self.socket.send_to(&data, &self.addr)
     }
 
     pub fn transfer(
@@ -58,24 +57,39 @@ impl AccountantStub {
         n: u64,
         keypair: &Ed25519KeyPair,
         to: PublicKey,
-    ) -> io::Result<usize> {
+    ) -> io::Result<Signature> {
         use log::{get_pubkey, sign_transaction_data};
         let from = get_pubkey(keypair);
         let sig = sign_transaction_data(&n, keypair, &to);
-        self.transfer_signed(from, to, n, sig)
+        self.transfer_signed(from, to, n, sig).map(|_| sig)
     }
 
     pub fn get_balance(self: &mut Self, pubkey: &PublicKey) -> io::Result<u64> {
-        let mut stream = TcpStream::connect(&self.addr)?;
         let req = Request::GetBalance { key: *pubkey };
         let data = serialize(&req).expect("serialize GetBalance");
-        stream.write(&data)?;
+        self.socket.send_to(&data, &self.addr)?;
         let mut buf = vec![0u8; 1024];
-        stream.read(&mut buf)?;
+        self.socket.recv_from(&mut buf)?;
         let resp = deserialize(&buf).expect("deserialize balance");
-        let Response::Balance { key, val } = resp;
-        assert_eq!(key, *pubkey);
-        Ok(val)
+        if let Response::Balance { key, val } = resp {
+            assert_eq!(key, *pubkey);
+            return Ok(val);
+        }
+        Ok(0)
+    }
+
+    pub fn wait_on_signature(self: &mut Self, wait_sig: &Signature) -> io::Result<()> {
+        let req = Request::Wait { sig: *wait_sig };
+        let data = serialize(&req).unwrap();
+        self.socket.send_to(&data, &self.addr).map(|_| ())?;
+
+        let mut buf = vec![0u8; 1024];
+        self.socket.recv_from(&mut buf)?;
+        let resp = deserialize(&buf).expect("deserialize signature");
+        if let Response::Confirmed { sig } = resp {
+            assert_eq!(sig, *wait_sig);
+        }
+        Ok(())
     }
 }
 
@@ -90,7 +104,8 @@ mod tests {
 
     #[test]
     fn test_accountant_stub() {
-        let addr = "127.0.0.1:8000";
+        let addr = "127.0.0.1:9000";
+        let send_addr = "127.0.0.1:9001";
         spawn(move || {
             let zero = Sha256Hash::default();
             let acc = Accountant::new(&zero, None);
@@ -100,17 +115,17 @@ mod tests {
 
         sleep(Duration::from_millis(30));
 
-        let mut acc = AccountantStub::new(addr);
+        let socket = UdpSocket::bind(send_addr).unwrap();
+        let mut acc = AccountantStub::new(addr, socket);
         let alice_keypair = generate_keypair();
         let bob_keypair = generate_keypair();
         acc.deposit(10_000, &alice_keypair).unwrap();
-        acc.deposit(1_000, &bob_keypair).unwrap();
+        let sig = acc.deposit(1_000, &bob_keypair).unwrap();
+        acc.wait_on_signature(&sig).unwrap();
 
-        sleep(Duration::from_millis(30));
         let bob_pubkey = get_pubkey(&bob_keypair);
-        acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
-
-        sleep(Duration::from_millis(300));
+        let sig = acc.transfer(500, &alice_keypair, bob_pubkey).unwrap();
+        acc.wait_on_signature(&sig).unwrap();
         assert_eq!(acc.get_balance(&bob_pubkey).unwrap(), 1_500);
     }
 }
diff --git a/src/bin/client-demo.rs b/src/bin/client-demo.rs
index e2ea5e56be..cbc0d6dd30 100644
--- a/src/bin/client-demo.rs
+++ b/src/bin/client-demo.rs
@@ -2,44 +2,39 @@ extern crate silk;
 
 fn main() {
     use silk::accountant_stub::AccountantStub;
-    use std::thread::sleep;
-    use std::time::Duration;
+    use std::time::Instant;
+    use std::net::UdpSocket;
     use silk::log::{generate_keypair, get_pubkey};
 
     let addr = "127.0.0.1:8000";
-    let mut acc = AccountantStub::new(addr);
+    let send_addr = "127.0.0.1:8001";
+    let socket = UdpSocket::bind(send_addr).unwrap();
+    let mut acc = AccountantStub::new(addr, socket);
     let alice_keypair = generate_keypair();
-    let bob_keypair = generate_keypair();
+    let alice_pubkey = get_pubkey(&alice_keypair);
     let txs = 10_000;
     println!("Depositing {} units in Alice's account...", txs);
-    acc.deposit(txs, &alice_keypair).unwrap();
-    //acc.deposit(1_000, &bob_keypair).unwrap();
+    let sig = acc.deposit(txs, &alice_keypair).unwrap();
+    acc.wait_on_signature(&sig).unwrap();
+    assert_eq!(acc.get_balance(&alice_pubkey).unwrap(), txs);
     println!("Done.");
 
-    sleep(Duration::from_millis(30));
-    let alice_pubkey = get_pubkey(&alice_keypair);
-    let bob_pubkey = get_pubkey(&bob_keypair);
     println!("Transferring 1 unit {} times...", txs);
+    let now = Instant::now();
+    let mut sig = sig;
     for _ in 0..txs {
-        acc.transfer(1, &alice_keypair, bob_pubkey).unwrap();
+        let bob_keypair = generate_keypair();
+        let bob_pubkey = get_pubkey(&bob_keypair);
+        sig = acc.transfer(1, &alice_keypair, bob_pubkey).unwrap();
     }
-    println!("Done.");
+    println!("Waiting for last transaction to be confirmed...",);
+    acc.wait_on_signature(&sig).unwrap();
 
-    sleep(Duration::from_millis(20));
-    let mut alice_val = acc.get_balance(&alice_pubkey).unwrap();
-    while alice_val > 0 {
-        println!("Checking on Alice's Balance {}", alice_val);
-        sleep(Duration::from_millis(20));
-        alice_val = acc.get_balance(&alice_pubkey).unwrap();
-    }
-    println!("Done. Checking balances.");
-    println!(
-        "Alice's Final Balance {}",
-        acc.get_balance(&alice_pubkey).unwrap()
-    );
-
-    println!(
-        "Bob's Final Balance {}",
-        acc.get_balance(&bob_pubkey).unwrap()
-    );
+    let duration = now.elapsed();
+    let ns = duration.as_secs() * 1_000_000_000 + duration.subsec_nanos() as u64;
+    let tps = (txs * 1_000_000_000) as f64 / ns as f64;
+    println!("Done. {} tps!", tps);
+    let val = acc.get_balance(&alice_pubkey).unwrap();
+    println!("Alice's Final Balance {}", val);
+    assert_eq!(val, 0);
 }
diff --git a/src/historian.rs b/src/historian.rs
index 99e2ff6006..1606080ed1 100644
--- a/src/historian.rs
+++ b/src/historian.rs
@@ -116,8 +116,8 @@ pub fn create_logger<T: 'static + Serialize + Clone + Debug + Send>(
 impl<T: 'static + Serialize + Clone + Debug + Send> Historian<T> {
     pub fn new(start_hash: &Sha256Hash, ms_per_tick: Option<u64>) -> Self {
         use std::sync::mpsc::sync_channel;
-        let (sender, event_receiver) = sync_channel(4000);
-        let (entry_sender, receiver) = sync_channel(4000);
+        let (sender, event_receiver) = sync_channel(1000);
+        let (entry_sender, receiver) = sync_channel(1000);
         let thread_hdl = create_logger(*start_hash, ms_per_tick, event_receiver, entry_sender);
         Historian {
             sender,