From a2f3ef937c8ada80f49a3bbbbdafd96fa58e8869 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hern=C3=A1n=20Di=20Pietro?= <hernan.di.pietro@gmail.com>
Date: Fri, 29 Oct 2021 11:17:55 -0300
Subject: [PATCH] NEW: VAA Verify stateless PyTeal

---
 teal/wormhole/pyteal/vaa-verify.py | 58 ++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 teal/wormhole/pyteal/vaa-verify.py

diff --git a/teal/wormhole/pyteal/vaa-verify.py b/teal/wormhole/pyteal/vaa-verify.py
new file mode 100644
index 000000000..35ac25ff9
--- /dev/null
+++ b/teal/wormhole/pyteal/vaa-verify.py
@@ -0,0 +1,58 @@
+#!/usr/bin/python3
+"""
+================================================================================================
+
+The VAA Signature Verify Stateless Program
+
+(c) 2021 Randlabs, Inc.
+
+------------------------------------------------------------------------------------------------
+
+This program verifies a subset of the signatures in a VAA against the guardian set. This
+program works in tandem with the VAA Processor stateful program.
+
+================================================================================================
+
+"""
+from pyteal import (compileTeal, Int, Mode, Txn, OnComplete, Itob, Btoi,
+                    ImportScratchValue,
+                    Return, Cond, Bytes, Global, Not, Gtxn, Seq, Approve, App, Assert, For, Len, And)
+from pyteal.ast import Subroutine
+from pyteal.ast.arg import Arg
+from pyteal.ast.txn import TxnType
+from pyteal.types import TealType
+
+from globals import SIGNATURES_PER_VERIFICATION_STEP, is_proper_group_size
+
+"""
+* Let N be the number of signatures per verification step, for the TX(i) in group, we verify signatures [j..k] where j = i*N, k = j+(N-1)
+* Input 0 is signatures [j..k] to verify as LogicSigArgs.
+* Input 1 is signed digest of payload, contained in the note field of the TX in current slot.
+* Input 2 is public keys for guardians [j..k] contained in the first Argument  of the TX in current slot.
+* Input 3 is guardian set size contained in the second argument of the TX in current slot.
+"""
+
+
+def vaa_verify_program(vaa_processor_app_id):
+    signatures = Arg(0)
+    digest = Txn.note()
+    keys = Txn.application_args[1]
+    gssize = Txn.application_args[2]
+
+    return Seq([
+        Assert(And(
+            Txn.fee() <= Int(1000),
+            Txn.application_args.length() == Int(1),
+            Len(signatures) == Int(SIGNATURES_PER_VERIFICATION_STEP) * Int(66),
+            Txn.rekey_to() == Global.zero_address(),
+            Txn.application_id() == Int(vaa_processor_app_id),
+            Txn.type_enum() == TxnType.ApplicationCall,
+            is_proper_group_size(Btoi(gssize))),),
+        Approve()])
+
+
+if __name__ == "__main__":
+    with open("vaa-verify.teal", "w") as f:
+        compiled = compileTeal(vaa_verify_program(
+            333), mode=Mode.Signature, version=5)
+        f.write(compiled)