signed_certificate_timestamp extension from RFC 6962

Author: tomato42

tlslite/constants.py

@@ -129,6 +129,7 @@ class ExtensionType(TLSEnum):
     srp = 12  # RFC 5054
     signature_algorithms = 13  # RFC 5246
     alpn = 16  # RFC 7301
+    signed_certificate_timestamp = 18  # RFC 6962
     client_hello_padding = 21  # RFC 7685
     encrypt_then_mac = 22  # RFC 7366
     extended_master_secret = 23  # RFC 7627

tlslite/extensions.py

@@ -1249,6 +1249,78 @@ def parse(self, parser):
         return self
 
 
+class SCTExtension(TLSExtension):
+    """
+    Client and Server Hello extension from Certificate Transparency.
+
+    Extension containing a list of serialised SignedCertificateTimestamp
+    objects.
+
+    See RFC 6962
+    """
+
+    def __init__(self):
+        """Create instance of class"""
+        extType = ExtensionType.signed_certificate_timestamp
+        super(SCTExtension, self).__init__(extType=extType)
+        self.sct_list = None
+
+    def create(self, sct_list):
+        """
+        Set the list of signed certificate timestamps
+
+        @type sct_list: list of bytearrays
+        @param sct_list: list of serialised certificate time stamps
+        """
+        self.sct_list = sct_list
+        return self
+
+    @property
+    def extData(self):
+        """
+        Return raw encoding of the extension
+
+        @rtype: bytearray
+        """
+        if self.sct_list is None:
+            return bytearray(0)
+
+        writer = Writer()
+        # elements have 2 byte header lengths
+        for sct in self.sct_list:
+            writer.add(len(sct), 2)
+            writer.bytes += sct
+
+        writer2 = Writer()
+        writer2.add(len(writer.bytes), 2)
+        return writer2.bytes + writer.bytes
+
+    def parse(self, parser):
+        """
+        Deserialise extension from on the wire data.
+
+        @type parser: L{tlslite.util.codec.Parser}
+        @param parser: data to be parsed
+
+        @rtype: L{SCTExtension}
+        """
+        if parser.getRemainingLength() == 0:
+            self.sct_list = None
+            return self
+
+        self.sct_list = []
+
+        parser.startLengthCheck(2)
+        while not parser.atLengthCheck():
+            self.sct_list.append(parser.getVarBytes(2))
+        parser.stopLengthCheck()
+
+        if parser.getRemainingLength() != 0:
+            raise SyntaxError("Trailing data in SCTExtension")
+
+        return self
+
+
 class StatusRequestExtension(TLSExtension):
     """
     Handling of the Certificate Status Request extension from RFC 6066.
@@ -1367,6 +1439,7 @@ def parse(self, parser):
         ExtensionType.srp: SRPExtension,
         ExtensionType.signature_algorithms: SignatureAlgorithmsExtension,
         ExtensionType.alpn: ALPNExtension,
+        ExtensionType.signed_certificate_timestamp: SCTExtension,
         ExtensionType.supports_npn: NPNExtension,
         ExtensionType.client_hello_padding: PaddingExtension,
         ExtensionType.renegotiation_info: RenegotiationInfoExtension}

unit_tests/test_tlslite_extensions.py

@@ -12,7 +12,8 @@
         SRPExtension, ClientCertTypeExtension, ServerCertTypeExtension,\
         TACKExtension, SupportedGroupsExtension, ECPointFormatsExtension,\
         SignatureAlgorithmsExtension, PaddingExtension, VarListExtension, \
-        RenegotiationInfoExtension, ALPNExtension, StatusRequestExtension
+        RenegotiationInfoExtension, ALPNExtension, StatusRequestExtension, \
+        SCTExtension
 from tlslite.utils.codec import Parser
 from tlslite.constants import NameType, ExtensionType, GroupName,\
         ECPointFormat, HashAlgorithm, SignatureAlgorithm, \
@@ -1588,6 +1589,90 @@ def test_parse_from_TLSExtension(self):
                                                bytearray(b'spdy/1')])
 
 
+class TestSCTExtension(unittest.TestCase):
+    def setUp(self):
+        self.ext = SCTExtension()
+
+    def test___int__(self):
+        self.assertIsNotNone(self.ext)
+        self.assertEqual(self.ext.extType, 18)
+        self.assertEqual(self.ext.extData, bytearray())
+        self.assertIsNone(self.ext.sct_list)
+
+    def test_create(self):
+        ext2 = self.ext.create([bytearray(b'SCT number 1'),
+                                bytearray(b'SCT number 2')])
+
+        self.assertIs(self.ext, ext2)
+        self.assertEqual(self.ext.sct_list, [bytearray(b'SCT number 1'),
+                                             bytearray(b'SCT number 2')])
+
+    def test_extData_with_empty_array(self):
+        self.ext.create([])
+
+        self.assertEqual(self.ext.extData, bytearray(b'\x00\x00'))
+
+    def test_extData_with_empty_SCTs(self):
+        self.ext.create([bytearray(), bytearray()])
+
+        self.assertEqual(self.ext.extData, bytearray(b'\x00\x04'
+                                                     b'\x00\x00'
+                                                     b'\x00\x00'))
+
+    def test_extData(self):
+        self.ext.create([bytearray(b'test'), bytearray(b'example')])
+
+        self.assertEqual(self.ext.extData, bytearray(b'\x00\x0f'
+                                                     b'\x00\x04test'
+                                                     b'\x00\x07example'))
+
+    def test_parse_with_empty_data(self):
+        parser = Parser(bytearray(b''))
+
+        ret = self.ext.parse(parser)
+
+        self.assertIs(ret, self.ext)
+        self.assertIsNone(self.ext.sct_list)
+
+    def test_parse_with_empty_array(self):
+        parser = Parser(bytearray(b'\x00\x00'))
+
+        ret = self.ext.parse(parser)
+
+        self.assertIs(ret, self.ext)
+        self.assertEqual(self.ext.sct_list, [])
+
+    def test_parse_with_empty_elements(self):
+        parser = Parser(bytearray(b'\x00\x04\x00\x00\x00\x00'))
+
+        self.ext.parse(parser)
+
+        self.assertEqual(self.ext.sct_list, [bytearray(), bytearray()])
+
+    def test_parse_with_value(self):
+        parser = Parser(bytearray(b'\x00\x06\x00\x04test'))
+
+        self.ext.parse(parser)
+
+        self.assertEqual(self.ext.sct_list, [bytearray(b'test')])
+
+    def test_parse_with_overflowing_data(self):
+        parser = Parser(bytearray(b'\x00\x00test'))
+
+        with self.assertRaises(SyntaxError):
+            self.ext.parse(parser)
+
+    def test_parse_from_TLSExtension(self):
+        ext = TLSExtension()
+
+        parser = Parser(bytearray(b'\x00\x12\x00\x08'
+                                  b'\x00\x06\x00\x04test'))
+
+        ret = ext.parse(parser)
+        self.assertIsInstance(ret, SCTExtension)
+        self.assertEqual(ret.sct_list, [bytearray(b'test')])
+
+
 class TestStatusRequestExtension(unittest.TestCase):
     def setUp(self):
         self.ext = StatusRequestExtension()