From 17c5b2842fa09d592d57a17a46bf9840a7d94d5a Mon Sep 17 00:00:00 2001
From: Joost Rijneveld <joost@joostrijneveld.nl>
Date: Wed, 27 Jan 2016 10:18:31 +0100
Subject: [PATCH] Make address masks more explicit and strict

---
 hash.c      |  4 ++--
 wots.c      |  4 ++--
 xmss.c      | 24 ++++++++++++------------
 xmss_fast.c | 24 ++++++++++++------------
 4 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/hash.c b/hash.c
index b403cb1..ed76207 100644
--- a/hash.c
+++ b/hash.c
@@ -13,8 +13,8 @@ Public domain.
 #include <openssl/evp.h>
 
 
-#define SET_KEY_BIT(a,b) (a[15] = (a[15] & 253) | (b << 1))
-#define SET_BLOCK_BIT(a,b) (a[15] = (a[15] & 254) | b)
+#define SET_KEY_BIT(a,b) (a[15] = (a[15] & 253) | ((b << 1) & 2))
+#define SET_BLOCK_BIT(a,b) (a[15] = (a[15] & 254) | (b & 1))
 
 #define WOTS_SELECT_KEY(a) (a[15] = (a[15] & 254) | 1)
 #define WOTS_SELECT_BLOCK(a) (a[15] = (a[15] & 254) | 0)
diff --git a/wots.c b/wots.c
index 41e3eec..a5c90a9 100644
--- a/wots.c
+++ b/wots.c
@@ -17,11 +17,11 @@ Public domain.
  * in the 16byte hash address
  */
 #define SET_HASH_ADDRESS(a, v) {\
-  a[15] = (a[15] & 1) | ((v << 1) & 255);\
+  a[15] = (a[15] & 1) | ((v << 1) & 254);\
   a[14] = (a[14] & 254) | ((v >> 7) & 1);}
   
 #define SET_CHAIN_ADDRESS(a, v) {\
-  a[14] = (a[14] & 1) | ((v << 1) & 255);\
+  a[14] = (a[14] & 1) | ((v << 1) & 254);\
   a[13] = (v >> 7) & 255;\
   a[12] = (a[12] & 254) | ((v >> 15) & 1);}
 
diff --git a/xmss.c b/xmss.c
index 1c77305..df63d54 100644
--- a/xmss.c
+++ b/xmss.c
@@ -24,23 +24,23 @@ Public domain.
  * in the 16byte hash address
  */
 #define SET_LAYER_ADDRESS(a, v) {\
-  a[6] = (a[6] & 3) | ((v << 2) & 255);\
-  a[5] = (a[5] & 252) | ((v >> 6) & 255);}  
+  a[6] = (a[6] & 3) | ((v << 2) & 252);\
+  a[5] = (a[5] & 252) | ((v >> 6) & 3);}
 
 #define SET_TREE_ADDRESS(a, v) {\
-  a[9] = (a[9] & 3) | ((v << 2) & 255);\
+  a[9] = (a[9] & 3) | ((v << 2) & 252);\
   a[8] = (v >> 6) & 255;\
   a[7] = (v >> 14) & 255;\
-  a[6] = (a[6] & 252) | ((v >> 22) & 255);}  
+  a[6] = (a[6] & 252) | ((v >> 22) & 3);}
   
 #define SET_OTS_BIT(a, b) {\
-  a[9] = (a[9] & 253) | (b << 1);}
+  a[9] = (a[9] & 253) | ((b << 1) & 2);}
 
 #define SET_OTS_ADDRESS(a, v) {\
-  a[12] = (a[12] & 1) | ((v << 1) & 255);\
+  a[12] = (a[12] & 1) | ((v << 1) & 254);\
   a[11] = (v >> 7) & 255;\
   a[10] = (v >> 15) & 255;\
-  a[9] = (a[9] & 254) | ((v >> 23) & 1);}  
+  a[9] = (a[9] & 254) | ((v >> 23) & 1);}
   
 #define ZEROISE_OTS_ADDR(a) {\
   a[12] = (a[12] & 254);\
@@ -49,7 +49,7 @@ Public domain.
   a[15] = 0;}
   
 #define SET_LTREE_BIT(a, b) {\
-  a[9] = (a[9] & 254) | b;}
+  a[9] = (a[9] & 254) | (b & 1);}
 
 #define SET_LTREE_ADDRESS(a, v) {\
   a[12] = v & 255;\
@@ -57,10 +57,10 @@ Public domain.
   a[10] = (v >> 16) & 255;}
 
 #define SET_LTREE_TREE_HEIGHT(a, v) {\
-  a[13] = (a[13] & 3) | ((v << 2) & 255);}
+  a[13] = (a[13] & 3) | ((v << 2) & 252);}
 
 #define SET_LTREE_TREE_INDEX(a, v) {\
-  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[15] = (a[15] & 3) | ((v << 2) & 252);\
   a[14] = (v >> 6) & 255;\
   a[13] = (a[13] & 252) | ((v >> 14) & 3);}
   
@@ -69,11 +69,11 @@ Public domain.
   a[11] = a[11] & 3;}  
 
 #define SET_NODE_TREE_HEIGHT(a, v) {\
-  a[12] = (a[12] & 3) | ((v << 2) & 255);\
+  a[12] = (a[12] & 3) | ((v << 2) & 252);\
   a[11] = (a[11] & 252) | ((v >> 6) & 3);}
 
 #define SET_NODE_TREE_INDEX(a, v) {\
-  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[15] = (a[15] & 3) | ((v << 2) & 252);\
   a[14] = (v >> 6) & 255;\
   a[13] = (v >> 14) & 255;\
   a[12] = (a[12] & 252) | ((v >> 22) & 3);}
diff --git a/xmss_fast.c b/xmss_fast.c
index f833029..dd656d7 100644
--- a/xmss_fast.c
+++ b/xmss_fast.c
@@ -24,23 +24,23 @@ Public domain.
  * in the 16byte hash address
  */
 #define SET_LAYER_ADDRESS(a, v) {\
-  a[6] = (a[6] & 3) | ((v << 2) & 255);\
-  a[5] = (a[5] & 252) | ((v >> 6) & 255);}  
+  a[6] = (a[6] & 3) | ((v << 2) & 252);\
+  a[5] = (a[5] & 252) | ((v >> 6) & 3);}
 
 #define SET_TREE_ADDRESS(a, v) {\
-  a[9] = (a[9] & 3) | ((v << 2) & 255);\
+  a[9] = (a[9] & 3) | ((v << 2) & 252);\
   a[8] = (v >> 6) & 255;\
   a[7] = (v >> 14) & 255;\
-  a[6] = (a[6] & 252) | ((v >> 22) & 255);}  
+  a[6] = (a[6] & 252) | ((v >> 22) & 3);}
   
 #define SET_OTS_BIT(a, b) {\
-  a[9] = (a[9] & 253) | (b << 1);}
+  a[9] = (a[9] & 253) | ((b << 1) & 2);}
 
 #define SET_OTS_ADDRESS(a, v) {\
-  a[12] = (a[12] & 1) | ((v << 1) & 255);\
+  a[12] = (a[12] & 1) | ((v << 1) & 254);\
   a[11] = (v >> 7) & 255;\
   a[10] = (v >> 15) & 255;\
-  a[9] = (a[9] & 254) | ((v >> 23) & 1);}  
+  a[9] = (a[9] & 254) | ((v >> 23) & 1);}
   
 #define ZEROISE_OTS_ADDR(a) {\
   a[12] = (a[12] & 254);\
@@ -49,7 +49,7 @@ Public domain.
   a[15] = 0;}
   
 #define SET_LTREE_BIT(a, b) {\
-  a[9] = (a[9] & 254) | b;}
+  a[9] = (a[9] & 254) | (b & 1);}
 
 #define SET_LTREE_ADDRESS(a, v) {\
   a[12] = v & 255;\
@@ -57,10 +57,10 @@ Public domain.
   a[10] = (v >> 16) & 255;}
 
 #define SET_LTREE_TREE_HEIGHT(a, v) {\
-  a[13] = (a[13] & 3) | ((v << 2) & 255);}
+  a[13] = (a[13] & 3) | ((v << 2) & 252);}
 
 #define SET_LTREE_TREE_INDEX(a, v) {\
-  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[15] = (a[15] & 3) | ((v << 2) & 252);\
   a[14] = (v >> 6) & 255;\
   a[13] = (a[13] & 252) | ((v >> 14) & 3);}
   
@@ -69,11 +69,11 @@ Public domain.
   a[11] = a[11] & 3;}  
 
 #define SET_NODE_TREE_HEIGHT(a, v) {\
-  a[12] = (a[12] & 3) | ((v << 2) & 255);\
+  a[12] = (a[12] & 3) | ((v << 2) & 252);\
   a[11] = (a[11] & 252) | ((v >> 6) & 3);}
 
 #define SET_NODE_TREE_INDEX(a, v) {\
-  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[15] = (a[15] & 3) | ((v << 2) & 252);\
   a[14] = (v >> 6) & 255;\
   a[13] = (v >> 14) & 255;\
   a[12] = (a[12] & 252) | ((v >> 22) & 3);}