From f59d31132c505063f045addb7719eb92ce9cee10 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@z.cash>
Date: Thu, 10 Jun 2021 23:57:45 +0100
Subject: [PATCH] Add Orchard empty root test vectors

---
 orchard_empty_roots.py | 23 +++++++++++++++++++++++
 orchard_merkle_tree.py |  8 ++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 orchard_empty_roots.py

diff --git a/orchard_empty_roots.py b/orchard_empty_roots.py
new file mode 100644
index 0000000..9358036
--- /dev/null
+++ b/orchard_empty_roots.py
@@ -0,0 +1,23 @@
+from orchard_merkle_tree import empty_roots
+from orchard_pallas import Fp
+from tv_output import render_args, render_tv
+from utils import i2lebsp
+
+
+def main():
+    args = render_args()
+
+    render_tv(
+        args,
+        'orchard_empty_roots',
+        (
+            ('empty_roots', '[[u8; 32]; 33]'),
+        ),
+        {
+            'empty_roots': list(map(bytes, empty_roots())),
+        },
+    )
+
+
+if __name__ == '__main__':
+    main()
diff --git a/orchard_merkle_tree.py b/orchard_merkle_tree.py
index ac3b5fb..3425b61 100644
--- a/orchard_merkle_tree.py
+++ b/orchard_merkle_tree.py
@@ -11,6 +11,7 @@ from utils import i2lebsp, leos2bsp
 # https://zips.z.cash/protocol/nu5.pdf#constants
 MERKLE_DEPTH = 32
 L_MERKLE = 255
+UNCOMMITTED_ORCHARD = Fp(2)
 
 # https://zips.z.cash/protocol/nu5.pdf#orchardmerklecrh
 def merkle_crh(layer, left, right):
@@ -30,3 +31,10 @@ right = leos2bsp(right)[:L_MERKLE]
 parent = Fp(626278560043615083774572461435172561667439770708282630516615972307985967801)
 assert merkle_crh(MERKLE_DEPTH - 1 - 25, left, right) == parent
 assert merkle_crh(MERKLE_DEPTH - 1 - 26, left, right) != parent
+
+def empty_roots():
+    empty_roots = [UNCOMMITTED_ORCHARD]
+    for layer in range(0, MERKLE_DEPTH)[::-1]:
+        bits = i2lebsp(L_MERKLE, empty_roots[-1].s)
+        empty_roots.append(merkle_crh(layer, bits, bits))
+    return empty_roots