diff --git a/src/accountant.rs b/src/accountant.rs
index 3a54c7c46af23a..50b76e529ace25 100644
--- a/src/accountant.rs
+++ b/src/accountant.rs
@@ -29,6 +29,7 @@ pub struct Accountant {
     pub balances: HashMap<PublicKey, i64>,
     pub first_id: Hash,
     pub last_id: Hash,
+    pub pending: HashMap<Signature, Transaction<i64>>,
 }
 
 impl Accountant {
@@ -49,6 +50,7 @@ impl Accountant {
             balances: HashMap::new(),
             first_id: start_hash,
             last_id: start_hash,
+            pending: HashMap::new(),
         };
 
         // The second item in the log is a special transaction where the to and from
@@ -104,12 +106,20 @@ impl Accountant {
             return Err(AccountingError::InvalidTransferSignature);
         }
 
+        if !tr.unless_any.is_empty() {
+            // TODO: Check to see if the transaction is expired.
+        }
+
         if !Self::is_deposit(allow_deposits, &tr.from, &tr.to) {
             if let Some(x) = self.balances.get_mut(&tr.from) {
                 *x -= tr.asset;
             }
         }
 
+        if !tr.if_all.is_empty() {
+            self.pending.insert(tr.sig, tr.clone());
+        }
+
         if self.balances.contains_key(&tr.to) {
             if let Some(x) = self.balances.get_mut(&tr.to) {
                 *x += tr.asset;
@@ -121,10 +131,39 @@ impl Accountant {
         Ok(())
     }
 
+    fn process_verified_sig(&mut self, _from: PublicKey, tx_sig: Signature) -> Result<()> {
+        if self.pending.contains_key(&tx_sig) {
+            if let Some(_tx) = self.pending.get_mut(&tx_sig) {
+                // Cancel:
+                // if Signature(from) is in unless_any, return funds to tx.from, and remove the tx from this map.
+
+                // Process Multisig:
+                // otherwise, if "Signature(from) is in if_all, remove it. If that causes that list
+                // to be empty, add the asset to to, and remove the tx from this map.
+            }
+        }
+        Ok(())
+    }
+
+    fn process_verified_timestamp(&mut self, _from: PublicKey, _dt: DateTime<Utc>) -> Result<()> {
+        // TODO: Lookup pending Transaction waiting on time, signed by a whitelisted PublicKey.
+
+        // Expire:
+        // if a Timestamp after this DateTime is in unless_any, return funds to tx.from,
+        // and remove the tx from this map.
+
+        // Process postponed:
+        // otherwise, if "Signature(from) is in if_all, remove it. If that causes that list
+        // to be empty, add the asset to to, and remove the tx from this map.
+        Ok(())
+    }
+
     fn process_verified_event(self: &mut Self, event: &Event, allow_deposits: bool) -> Result<()> {
         match *event {
             Event::Tick => Ok(()),
             Event::Transaction(ref tr) => self.process_verified_transaction(tr, allow_deposits),
+            Event::Signature { from, tx_sig, .. } => self.process_verified_sig(from, tx_sig),
+            Event::Timestamp { from, dt, .. } => self.process_verified_timestamp(from, dt),
         }
     }
 
diff --git a/src/event.rs b/src/event.rs
index 12a848ab5f47c8..444f21b9c82282 100644
--- a/src/event.rs
+++ b/src/event.rs
@@ -1,7 +1,9 @@
 //! The `event` crate provides the data structures for log events.
 
-use signature::Signature;
+use signature::{PublicKey, Signature, SignatureUtil};
 use transaction::Transaction;
+use chrono::prelude::*;
+use bincode::serialize;
 
 /// When 'event' is Tick, the event represents a simple clock tick, and exists for the
 /// sole purpose of improving the performance of event log verification. A tick can
@@ -12,13 +14,26 @@ use transaction::Transaction;
 pub enum Event {
     Tick,
     Transaction(Transaction<i64>),
+    Signature {
+        from: PublicKey,
+        tx_sig: Signature,
+        sig: Signature,
+    },
+    Timestamp {
+        from: PublicKey,
+        dt: DateTime<Utc>,
+        sig: Signature,
+    },
 }
 
 impl Event {
+    // TODO: Rename this to transaction_signature().
     pub fn get_signature(&self) -> Option<Signature> {
         match *self {
             Event::Tick => None,
             Event::Transaction(ref tr) => Some(tr.sig),
+            Event::Signature { .. } => None,
+            Event::Timestamp { .. } => None,
         }
     }
 
@@ -26,6 +41,8 @@ impl Event {
         match *self {
             Event::Tick => true,
             Event::Transaction(ref tr) => tr.verify(),
+            Event::Signature { from, tx_sig, sig } => sig.verify(&from, &tx_sig),
+            Event::Timestamp { from, dt, sig } => sig.verify(&from, &serialize(&dt).unwrap()),
         }
     }
 }
diff --git a/src/transaction.rs b/src/transaction.rs
index 8256da28d3d003..3f2a1e99d41c59 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -8,8 +8,8 @@ use chrono::prelude::*;
 
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
 pub enum Condition {
-    DateTime(DateTime<Utc>),
-    Cancel,
+    Timestamp(DateTime<Utc>),
+    Signature(PublicKey),
 }
 
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
@@ -45,11 +45,12 @@ impl<T: Serialize> Transaction<T> {
         asset: T,
         last_id: Hash,
     ) -> Self {
+        let from = from_keypair.pubkey();
         let mut tr = Transaction {
-            from: from_keypair.pubkey(),
+            from,
             to,
-            if_all: vec![Condition::DateTime(dt)],
-            unless_any: vec![Condition::Cancel],
+            if_all: vec![Condition::Timestamp(dt)],
+            unless_any: vec![Condition::Signature(from)],
             asset,
             last_id,
             sig: Signature::default(),