fixed two minor points in handling the maximum signature value

test/xmss_max_signatures.c

@@ -21,7 +21,7 @@
     #define XMSS_SIGN xmssmt_sign
     #define XMSS_SIGN_OPEN xmssmt_sign_open
     #define XMSS_VARIANT "XMSSMT-SHA2_20/2_256"
-    #define XMSS_SIGNATURES 1 << 20
+    #define XMSS_SIGNATURES (1 << 20)
 #else
     #define XMSS_PARSE_OID xmss_parse_oid
     #define XMSS_STR_TO_OID xmss_str_to_oid
@@ -29,7 +29,7 @@
     #define XMSS_SIGN xmss_sign
     #define XMSS_SIGN_OPEN xmss_sign_open
     #define XMSS_VARIANT "XMSS-SHA2_10_256"
-    #define XMSS_SIGNATURES 1 << 10
+    #define XMSS_SIGNATURES (1 << 10)
 #endif
 
 int main()
@@ -72,27 +72,28 @@ int main()
     }
     if(ret == 0)
             printf("As expected, return code was 0\n");
-    i++;
-    printf("  - iteration #%d:\n", i);
+    for (; i < (XMSS_SIGNATURES) + 2; i++) {
+        printf("  - iteration #%d:\n", i);
 
-    return_code = XMSS_SIGN(sk, sm, &smlen, m, XMSS_MLEN);
+        return_code = XMSS_SIGN(sk, sm, &smlen, m, XMSS_MLEN);
 
-    if (return_code == 0) {
-        printf("  Error! Return code was %d\n",return_code);
-        ret = -1;
-    }
-    else {
-        printf("Return code as expected [%d].\n", return_code);
+        if (return_code == 0) {
+                printf("  Error! Return code was %d\n",return_code);
+                ret = -1;
+        }
+        else {
+                printf("Return code as expected [%d].\n", return_code);
+        }
+        
+        idx = (unsigned long)bytes_to_ull(sk, params.index_bytes);
+        printf("Index: %llu\n", idx);
+        printf("Secret key: %llu\n", idx);
+        for (j = 0; j < XMSS_OID_LEN + params.sk_bytes;j++)
+                printf("%d ", sk[j]);
+        
+        printf("\n");
     }
     
-    idx = (unsigned long)bytes_to_ull(sk, params.index_bytes);
-    printf("Index: %llu\n", idx);
-    printf("Secret key: %llu\n", idx);
-    for (j = 0; j < XMSS_OID_LEN + params.sk_bytes;j++)
-            printf("%d ", sk[j]);
-    
-    printf("\n");
-    
     free(m);
     free(sm);
     free(mout);

xmss_core.c

@@ -222,14 +222,11 @@ int xmssmt_core_sign(const xmss_params *params,
     if (idx >= ((1ULL << params->full_height) - 1)) {
         // Delete secret key here. We only do this in memory, production code
         // has to make sure that this happens on disk.
-        sk[0] = 255;
-        sk[1] = 255;
-        sk[2] = 255;
-        sk[3] = 255;
+        memset(sk, 0xFF, params->index_bytes);
         memset(sk + params->index_bytes, 0, (params->sk_bytes - params->index_bytes));
         if (idx > ((1ULL << params->full_height) - 1))
             return -2; // We already used all one-time keys
-        if ((params->full_height == 64) && (idx = ((1ULL << params->full_height) - 1))) 
+        if ((params->full_height == 64) && (idx == ((1ULL << params->full_height) - 1))) 
                 return -2; // We already used all one-time keys
     }
     

xmss_core_fast.c

@@ -615,14 +615,11 @@ int xmss_core_sign(const xmss_params *params,
     if (idx >= ((1ULL << params->full_height) - 1)) {
         // Delete secret key here. We only do this in memory, production code
         // has to make sure that this happens on disk.
-        sk[0] = 255;
-        sk[1] = 255;
-        sk[2] = 255;
-        sk[3] = 255;
+        memset(sk, 0xFF, params->index_bytes);
         memset(sk + params->index_bytes, 0, (params->sk_bytes - params->index_bytes));
         if (idx > ((1ULL << params->full_height) - 1))
             return -2; // We already used all one-time keys
-        if ((params->full_height == 64) && (idx = ((1ULL << params->full_height) - 1))) 
+        if ((params->full_height == 64) && (idx == ((1ULL << params->full_height) - 1))) 
                 return -2; // We already used all one-time keys
     }
     
@@ -839,14 +836,11 @@ int xmssmt_core_sign(const xmss_params *params,
     if (idx >= ((1ULL << params->full_height) - 1)) {
         // Delete secret key here. We only do this in memory, production code
         // has to make sure that this happens on disk.
-        sk[0] = 255;
-        sk[1] = 255;
-        sk[2] = 255;
-        sk[3] = 255;
+        memset(sk, 0xFF, params->index_bytes);
         memset(sk + params->index_bytes, 0, (params->sk_bytes - params->index_bytes));
         if (idx > ((1ULL << params->full_height) - 1))
             return -2; // We already used all one-time keys
-        if ((params->full_height == 64) && (idx = ((1ULL << params->full_height) - 1))) 
+        if ((params->full_height == 64) && (idx == ((1ULL << params->full_height) - 1))) 
                 return -2; // We already used all one-time keys
     }