diff --git a/reverse-sandbox/operation_node.py b/reverse-sandbox/operation_node.py
index bb59317..2d85634 100644
--- a/reverse-sandbox/operation_node.py
+++ b/reverse-sandbox/operation_node.py
@@ -426,7 +426,7 @@ def __eq__(self, other):
         return self.raw == other.raw
 
     def __hash__(self):
-        return struct.unpack('<I', ''.join([chr(v) for v in self.raw[:4]]))[0]
+        return struct.unpack('<I', b''.join([bytes([v]) for v in self.raw[:4]]))[0]
 
 
 # Operation nodes processed so far.
diff --git a/reverse-sandbox/regex_parser_v1.py b/reverse-sandbox/regex_parser_v1.py
index c11e8eb..5a64f86 100644
--- a/reverse-sandbox/regex_parser_v1.py
+++ b/reverse-sandbox/regex_parser_v1.py
@@ -111,11 +111,11 @@ def parse_parantheses_close(node_type, node_arg, node_transition, node_idx):
 
 def node_parse(re, i, regex_list, node_idx):
     node_type = struct.unpack('>I',
-        ''.join([chr(x) for x in re[i:i+4]]))[0]
+        b''.join([bytes([x]) for x in re[i:i+4]]))[0]
     node_transition = struct.unpack('>I',
-        ''.join([chr(x) for x in re[i+4:i+8]]))[0]
+        b''.join([bytes([x]) for x in re[i+4:i+8]]))[0]
     node_arg = struct.unpack('>I',
-        ''.join([chr(x) for x in re[i+8:i+12]]))[0]
+        b''.join([bytes([x]) for x in re[i+8:i+12]]))[0]
     i += 12
 
     logger.debug('node idx:{:#010x} type: {:#02x} arg: {:#010x}' \
@@ -136,10 +136,10 @@ def transform(x):
             return c
 
     class_size = struct.unpack('>I',
-        ''.join([chr(x) for x in re[i:i+4]]))[0]
+        b''.join([bytes([x]) for x in re[i:i+4]]))[0]
     i += 0x4
     content = struct.unpack('>{}I'.format(class_size),
-        ''.join([chr(x) for x in re[i:i+4*class_size]]))
+        b''.join([bytes([x]) for x in re[i:i+4*class_size]]))
     i += 0x4 * class_size
     assert(class_size % 2 == 0)
 
@@ -162,23 +162,23 @@ class RegexParser(object):
     @staticmethod
     def parse(re, i, regex_list):
         node_count = struct.unpack('>I',
-            ''.join([chr(x) for x in re[i:i+0x4]]))[0]
+            b''.join([bytes([x]) for x in re[i:i+0x4]]))[0]
         logger.debug('node count = {:#x}'.format(node_count))
 
         start_node = struct.unpack('>I',
-            ''.join([chr(x) for x in re[i+0x4:i+0x8]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x4:i+0x8]]))[0]
         logger.debug('start node = {:#x}'.format(start_node))
 
         end_node = struct.unpack('>I',
-            ''.join([chr(x) for x in re[i+0x8:i+0xC]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x8:i+0xC]]))[0]
         logger.debug('end node = {:#x}'.format(end_node))
 
         cclass_count = struct.unpack('>I',
-            ''.join([chr(x) for x in re[i+0xC:i+0x10]]))[0]
+            b''.join([bytes([x]) for x in re[i+0xC:i+0x10]]))[0]
         logger.debug('character class count = {:#x}'.format(cclass_count))
 
         submatch_count = struct.unpack('>I',
-            ''.join([chr(x) for x in re[i+0x10:i+0x14]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x10:i+0x14]]))[0]
         i += 0x14
         logger.debug('submatch count = {:#x}'.format(submatch_count))
 
diff --git a/reverse-sandbox/regex_parser_v2.py b/reverse-sandbox/regex_parser_v2.py
index cd8c1ed..dffbb9b 100644
--- a/reverse-sandbox/regex_parser_v2.py
+++ b/reverse-sandbox/regex_parser_v2.py
@@ -112,13 +112,13 @@ def parse_parantheses_close(node_type, node_arg, node_transition, node_idx):
 
 def node_parse(re, i, regex_list, node_idx):
     node_type = struct.unpack('<B',
-        ''.join([chr(x) for x in re[i:i+1]]))[0]
+        b''.join([bytes([x]) for x in re[i:i+1]]))[0]
     node_transition = struct.unpack('<H',
-        ''.join([chr(x) for x in re[i+1:i+3]]))[0]
+        b''.join([bytes([x]) for x in re[i+1:i+3]]))[0]
     pad = struct.unpack('<B',
-        ''.join([chr(x) for x in re[i+3:i+4]]))[0]
+        b''.join([bytes([x]) for x in re[i+3:i+4]]))[0]
     node_arg = struct.unpack('<I',
-        ''.join([chr(x) for x in re[i+4:i+8]]))[0]
+        b''.join([bytes([x]) for x in re[i+4:i+8]]))[0]
     i += 8
 
     logger.debug('node idx:{:#06x} type: {:#02x} arg: {:#010x}' \
@@ -156,17 +156,17 @@ def transform_content(content):
         return
 
     classes_magic, classes_size = struct.unpack('<II',
-        ''.join([chr(x) for x in re[i:i+8]]))
+        b''.join([bytes([x]) for x in re[i:i+8]]))
     i += 0x8
     logger.debug('classes magic = {:#x} size = {:#x}'.format(
         classes_magic, classes_size))
     assert(len(re) - i == classes_size)
     starts = struct.unpack('<{}I'.format(cclass_count),
-        ''.join([chr(x) for x in re[i:i+4*cclass_count]]))
+        b''.join([bytes([x]) for x in re[i:i+4*cclass_count]]))
     i += 0x4 * cclass_count
 
     lens = struct.unpack('<{}B'.format(cclass_count),
-        ''.join([chr(x) for x in re[i:i+cclass_count]]))
+        b''.join([bytes([x]) for x in re[i:i+cclass_count]]))
     i += cclass_count
 
     contents = [re[i+start:i+start+clen] for start, clen in zip(starts, lens)]
@@ -177,23 +177,23 @@ class RegexParser(object):
     @staticmethod
     def parse(re, i, regex_list):
         magic = struct.unpack('<I',
-            ''.join([chr(x) for x in re[i:i+0x4]]))[0]
+            b''.join([bytes([x]) for x in re[i:i+0x4]]))[0]
         logger.debug('magic = {:#x}'.format(magic))
 
         node_count = struct.unpack('<I',
-            ''.join([chr(x) for x in re[i+0x4:i+0x8]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x4:i+0x8]]))[0]
         logger.debug('node count = {:#x}'.format(node_count))
 
         start_node = struct.unpack('<I',
-            ''.join([chr(x) for x in re[i+0x8:i+0xC]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x8:i+0xC]]))[0]
         logger.debug('start node = {:#x}'.format(start_node))
 
         end_node = struct.unpack('<I',
-            ''.join([chr(x) for x in re[i+0xC:i+0x10]]))[0]
+            b''.join([bytes([x]) for x in re[i+0xC:i+0x10]]))[0]
         logger.debug('end node = {:#x}'.format(end_node))
 
         cclass_count = struct.unpack('<I',
-            ''.join([chr(x) for x in re[i+0x10:i+0x14]]))[0]
+            b''.join([bytes([x]) for x in re[i+0x10:i+0x14]]))[0]
         logger.debug('character class count = {:#x}'.format(cclass_count))
         i += 0x14
 
diff --git a/reverse-sandbox/regex_parser_v3.py b/reverse-sandbox/regex_parser_v3.py
index 4c89da7..ac93983 100644
--- a/reverse-sandbox/regex_parser_v3.py
+++ b/reverse-sandbox/regex_parser_v3.py
@@ -146,7 +146,7 @@ class RegexParser(object):
 
     @staticmethod
     def parse(re, i, regex_list):
-        length = struct.unpack('<H', ''.join([chr(x) for x in re[i:i+2]]))[0]
+        length = struct.unpack('<H', b''.join([bytes([x]) for x in re[i:i+2]]))[0]
         logger.debug("re.length: 0x%x", length)
         i += 2
         assert(length == len(re)-i)
diff --git a/reverse-sandbox/reverse_sandbox.py b/reverse-sandbox/reverse_sandbox.py
index 257df3a..323c0f1 100644
--- a/reverse-sandbox/reverse_sandbox.py
+++ b/reverse-sandbox/reverse_sandbox.py
@@ -34,7 +34,12 @@ def extract_string_from_offset(f, offset, ios_version):
     else:
         f.seek(offset * 8)
         len = struct.unpack("<I", f.read(4))[0]-1
-    return '%s' % f.read(len)
+    ret = f.read(len)
+    try:
+       ret = ret.decode()
+    except:
+        pass
+    return ret
 
 
 def create_operation_nodes(infile, regex_list, num_operation_nodes,
@@ -43,10 +48,10 @@ def create_operation_nodes(infile, regex_list, num_operation_nodes,
     operation_nodes = operation_node.build_operation_nodes(infile,
         num_operation_nodes, ios_major_version)
     logger.info("operation nodes")
-    
+
     for idx, node in enumerate(operation_nodes):
         logger.info("%d: %s", idx, node.str_debug())
-    
+
     for n in operation_nodes:
         n.convert_filter(sandbox_filter.convert_filter_callback, infile,
                     regex_list, ios_major_version, keep_builtin_filters,
@@ -211,7 +216,7 @@ def get_global_vars(f, vars_offset, num_vars, base_offset):
             len = struct.unpack("<I", f.read(4))[0]
         s = f.read(len-1)
         global_vars.append(s)
-    logger.info("global variables are {:s}".format(", ".join(s for s in global_vars)))
+    logger.info("global variables are {:s}".format(", ".join(s.decode() for s in global_vars)))
     return global_vars
 
 def get_base_addr(f, ios_version):
@@ -304,7 +309,7 @@ def main():
         re_table_offset = 12
     else:
         re_table_offset = struct.unpack("<H", f.read(2))[0]
-    
+
     if get_ios_major_version(args.release) >= 12:
         f.seek(8)
     re_table_count = struct.unpack("<H", f.read(2))[0]
@@ -319,7 +324,7 @@ def main():
             f.seek(re_table_offset)
         else:
             f.seek(re_table_offset * 8)
-        
+
         re_offsets_table = struct.unpack("<%dH" % re_table_count, f.read(2 * re_table_count))
         for offset in re_offsets_table:
             if get_ios_major_version(args.release) >= 13:
@@ -328,7 +333,7 @@ def main():
             else:
                 f.seek(offset * 8)
                 re_length = struct.unpack("<I", f.read(4))[0]
-            
+
             re = struct.unpack("<%dB" % re_length, f.read(re_length))
             logger.debug("total_re_length: 0x%x", re_length)
             re_debug_str = "re: [", ", ".join([hex(i) for i in re]), "]"
@@ -397,7 +402,7 @@ def main():
                     break
             start = f.tell()
             end = re_table_offset * 8
-            num_operation_nodes = (end - start) / 8
+            num_operation_nodes = (end - start) // 8
         logger.info("number of operation nodes: %u" % num_operation_nodes)
 
         operation_nodes = create_operation_nodes(f, regex_list,
@@ -489,7 +494,8 @@ def main():
                 break
         start = f.tell()
         end = re_table_offset * 8
-        num_operation_nodes = (end - start) / 8
+        # has to be int and not float
+        num_operation_nodes = (end - start) // 8
         logger.info("number of operation nodes: %d ; start: %#x" % (num_operation_nodes, start))
 
         operation_nodes = create_operation_nodes(f, regex_list,
diff --git a/reverse-sandbox/reverse_string.py b/reverse-sandbox/reverse_string.py
index dd11126..00af63a 100644
--- a/reverse-sandbox/reverse_string.py
+++ b/reverse-sandbox/reverse_string.py
@@ -146,11 +146,14 @@ def get_length_minus_1(self):
     def read_token(self, substr_len):
         self.token_stack.append(self.token)
         self.token = self.binary_string[self.pos:self.pos+substr_len]
-        logger.debug("got token \"{:s}\"".format(self.token))
+        logger.debug("got token \"{:s}\"".format(self.token.decode()))
         self.pos += substr_len
 
     def update_base(self):
-        self.base += self.token
+        if isinstance(self.token, bytes):
+            self.base += self.token.decode()
+        else:
+            self.base += self.token
         self.token = ""
         logger.debug("update base to \"{:s}\"".format(self.base))
 
@@ -168,14 +171,18 @@ def get_last_byte(self):
 
     def get_substring(self, substr_len):
         substr = self.binary_string[self.pos:self.pos+substr_len]
-        logger.debug(" ".join("0x{:02x}".format(ord(c)) for c in substr))
+        logger.debug(" ".join("0x{:02x}".format(c) for c in substr))
         self.pos += substr_len
         return substr
 
     def end_with_subtokens(self, subtokens):
         for s in subtokens:
-            self.output_strings.append(self.base+self.token+s)
-            logger.debug("output string with subtokens \"{:s}\"".format(self.base+self.token+s))
+            if isinstance(self.token, bytes):
+                self.output_strings.append(self.base+self.token.decode()+s)
+                logger.debug("output string with subtokens \"{:s}\"".format(self.base+self.token.decode()+s))
+            else:
+                self.output_strings.append(self.base+self.token+s)
+                logger.debug("output string with subtokens \"{:s}\"".format(self.base+self.token+s))
         self.token = ""
 
     def is_end(self):
@@ -227,7 +234,7 @@ def parse_byte_string(self, s, global_vars):
                 logger.debug("state is STATE_CONSTANT_READ")
                 b = rss.get_last_byte()
                 if b >= 0x10 and b < 0x3f:
-                    rss.token = "${" + global_vars[b-0x10] + "}"
+                    rss.token = b"${" + global_vars[b-0x10] + b"}"
                 b = rss.get_next_byte()
                 rss.update_state(b)
             elif rss.state == rss.STATE_CONCAT_BYTE_READ:
@@ -335,7 +342,7 @@ def parse_byte_string(self, s, global_vars):
             logger.warn("last state is not STATE_END_BYTE_READ ({:d})".format(rss.state))
             logger.warn("previous state ({:d})".format(rss.state_stack[len(rss.state_stack)-1]))
 
-        logger.info("initial string: " + " ".join("0x{:02x}".format(ord(c)) for c in s))
+        logger.info("initial string: " + " ".join("0x{:02x}".format(c) for c in s))
         logger.info("output_strings (num: {:d}): {:s}".format(len(rss.output_strings), ",".join('"{:s}"'.format(s) for s in rss.output_strings)))
         return rss.output_strings
 
diff --git a/reverse-sandbox/sandbox_filter.py b/reverse-sandbox/sandbox_filter.py
index 1df0f12..e5d7cb2 100644
--- a/reverse-sandbox/sandbox_filter.py
+++ b/reverse-sandbox/sandbox_filter.py
@@ -37,7 +37,7 @@ def get_filter_arg_string_by_offset(f, offset):
     if ios_major_version >= 10:
         f.seek(offset * 8)
         s = f.read(4+len)
-        logger.info("binary string is " + s.encode("hex"))
+        logger.info("binary string is " + s.hex())
         ss = reverse_string.SandboxString()
         myss = ss.parse_byte_string(s[4:], global_vars)
         actual_string = ""
@@ -72,7 +72,7 @@ def get_filter_arg_string_by_offset_with_type(f, offset):
     if ios_major_version >= 10:
         f.seek(base_addr + offset * 8)
         s = f.read(4+len)
-        logger.info("binary string is " + s.encode("hex"))
+        logger.info("binary string is " + s.hex())
         ss = reverse_string.SandboxString()
         myss = ss.parse_byte_string(s[4:], global_vars)
         append = "literal"
diff --git a/reverse-sandbox/sandbox_regex.py b/reverse-sandbox/sandbox_regex.py
index 9a3f14a..effbab6 100644
--- a/reverse-sandbox/sandbox_regex.py
+++ b/reverse-sandbox/sandbox_regex.py
@@ -456,7 +456,7 @@ def create_regex_list(re):
 
     regex_list = []
 
-    version = struct.unpack('>I', ''.join([chr(x) for x in re[:4]]))[0]
+    version = struct.unpack('>I', b''.join([bytes(chr(x), 'utf-8') for x in re[:4]]))[0]
     logger.debug("re.version: 0x%x", version)
 
     i = 4