From 146d89ef22c88dccb52821541f7cb8ebd59d739e Mon Sep 17 00:00:00 2001
From: "Peter D. Gray" <peter@conalgo.com>
Date: Fri, 25 May 2018 10:18:08 -0400
Subject: [PATCH] Support set of initial counter value for CTR modes

---
 modtcc-aes.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/modtcc-aes.c b/modtcc-aes.c
index 4f27d73..3dae9b2 100644
--- a/modtcc-aes.c
+++ b/modtcc-aes.c
@@ -63,7 +63,8 @@ STATIC mp_obj_t mod_trezorcrypto_AES_make_new(const mp_obj_type_t *type, size_t
         memset(o->iv, 0, AES_BLOCK_SIZE);
     }
 
-    memset(o->ctr, 0, AES_BLOCK_SIZE);
+    // for CTR modes, use IV
+    memcpy(o->ctr, o->iv, AES_BLOCK_SIZE);
 
     switch (key.len) {
         default: