diff --git a/abc/txstore.nim b/abc/txstore.nim
new file mode 100644
index 0000000..36a7d97
--- /dev/null
+++ b/abc/txstore.nim
@@ -0,0 +1,30 @@
+import std/tables
+import std/hashes
+import ./transactions
+
+type
+  TxStore* = object
+    genesis: TxHash
+    transactions: Table[TxHash, Transaction]
+
+export transactions
+
+func hash(h: TxHash): Hash =
+  h.toBytes.hash
+
+func add*(store: var TxStore, transactions: varargs[Transaction]) =
+  for transaction in transactions:
+    store.transactions[transaction.hash] = transaction
+
+func init*(_: type TxStore, genesis: Transaction): TxStore =
+  result.genesis = genesis.hash
+  result.add(genesis)
+
+func genesis*(store: TxStore): TxHash =
+  store.genesis
+
+func hasTx*(store: TxStore, hash: TxHash): bool =
+  store.transactions.hasKey(hash)
+
+func `[]`*(store: TxStore, hash: TxHash): Transaction =
+  store.transactions[hash]
diff --git a/tests/testTxStore.nim b/tests/testTxStore.nim
new file mode 100644
index 0000000..e003d1d
--- /dev/null
+++ b/tests/testTxStore.nim
@@ -0,0 +1,20 @@
+import abc/txstore
+import ./basics
+import ./alicebob
+
+suite "Transaction Store":
+
+  let genesis = Transaction.genesis
+  let transaction = Transaction.example
+
+  test "is initialized with a genesis transaction":
+    let store = TxStore.init(genesis)
+    check store.hasTx(genesis.hash)
+    check store[genesis.hash] == genesis
+
+  test "stores transactions":
+    var store = TxStore.init(genesis)
+    check not store.hasTx(transaction.hash)
+    store.add(transaction)
+    check store.hasTx(transaction.hash)
+    check store[transaction.hash] == transaction