diff --git a/utils/sbtools/sbtoelf.c b/utils/sbtools/sbtoelf.c
index 87017ab..023964f 100644
--- a/utils/sbtools/sbtoelf.c
+++ b/utils/sbtools/sbtoelf.c
@@ -89,6 +89,18 @@ static uint8_t instruction_checksum(struct sb_instruction_header_t *hdr)
 static void elf_write(void *user, uint32_t addr, const void *buf, size_t count)
 {
     FILE *f = user;
+    /* if seeking paste end of file, write constant 0xff otherwise the system
+     * might write random bytes and it's not good to reproduce problems */
+    #if 1
+    fseek(f, 0, SEEK_END);
+    size_t pos = ftell(f);
+    if(pos < addr)
+    {
+        uint8_t zero = 0xff;
+        while(pos++ < addr)
+            fwrite(&zero, 1, 1, f);
+    }
+    #endif
     fseek(f, addr, SEEK_SET);
     fwrite(buf, count, 1, f);
 }
@@ -481,6 +493,15 @@ static void extract(unsigned long filesize)
         }
     }

+    if(getenv("SB_REAL_KEY") != 0)
+    {
+        struct crypto_key_t k;
+        char *env = getenv("SB_REAL_KEY");
+        if(!parse_key(&env, &k) || *env)
+            bug("Invalid SB_REAL_KEY");
+        memcpy(real_key, k.u.key, 16);
+    }
+
     color(RED);
     printf("  Summary:\n");
     color(GREEN);
@@ -751,6 +772,9 @@ int main(int argc, char **argv)
                 add_keys(&g_zero_key, 1);
                 break;
             }
+            case 'r':
+                g_raw_mode = true;
+                break;
             case 'a':
             {
                 struct crypto_key_t key;