예제 #1
0
    def setUp(self):
        # Reuse the policy_config subdirectory for the temporary SQLite files.
        self.dKeyDatabaseFilePath = "policy_config/manager-d-key-test.db"
        try:
            os.remove(self.dKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.eKeyDatabaseFilePath = "policy_config/manager-e-key-test.db"
        try:
            os.remove(self.eKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.intervalDatabaseFilePath = "policy_config/manager-interval-test.db"
        try:
            os.remove(self.intervalDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.groupKeyDatabaseFilePath = "policy_config/manager-group-key-test.db"
        try:
            os.remove(self.groupKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        params = RsaKeyParams()
        memberDecryptKey = RsaAlgorithm.generateKey(params)
        self.decryptKeyBlob = memberDecryptKey.getKeyBits()
        memberEncryptKey = RsaAlgorithm.deriveEncryptKey(self.decryptKeyBlob)
        self.encryptKeyBlob = memberEncryptKey.getKeyBits()

        # Generate the certificate.
        self.certificate = IdentityCertificate()
        self.certificate.setName(Name("/ndn/memberA/KEY/ksk-123/ID-CERT/123"))
        contentPublicKey = PublicKey(self.encryptKeyBlob)
        self.certificate.setPublicKeyInfo(contentPublicKey)
        self.certificate.setNotBefore(0)
        self.certificate.setNotAfter(0)
        self.certificate.encode()

        signatureInfoBlob = Blob(SIG_INFO, False)
        signatureValueBlob = Blob(SIG_VALUE, False)

        signature = TlvWireFormat.get().decodeSignatureInfoAndValue(
            signatureInfoBlob.buf(), signatureValueBlob.buf())
        self.certificate.setSignature(signature)

        self.certificate.wireEncode()

        # Set up the keyChain.
        identityStorage = MemoryIdentityStorage()
        privateKeyStorage = MemoryPrivateKeyStorage()
        self.keyChain = KeyChain(
            IdentityManager(identityStorage, privateKeyStorage),
            NoVerifyPolicyManager())
        identityName = Name("TestGroupManager")
        self.keyChain.createIdentityAndCertificate(identityName)
        self.keyChain.getIdentityManager().setDefaultIdentity(identityName)
예제 #2
0
    def test_import_export(self):
        privateKeyPkcs1Base64 = (
          "MIIEpAIBAAKCAQEAw0WM1/WhAxyLtEqsiAJgWDZWuzkYpeYVdeeZcqRZzzfRgBQT\n" +
          "sNozS5t4HnwTZhwwXbH7k3QN0kRTV826Xobws3iigohnM9yTK+KKiayPhIAm/+5H\n" +
          "GT6SgFJhYhqo1/upWdueojil6RP4/AgavHhopxlAVbk6G9VdVnlQcQ5Zv0OcGi73\n" +
          "c+EnYD/YgURYGSngUi/Ynsh779p2U69/te9gZwIL5PuE9BiO6I39cL9z7EK1SfZh\n" +
          "OWvDe/qH7YhD/BHwcWit8FjRww1glwRVTJsA9rH58ynaAix0tcR/nBMRLUX+e3rU\n" +
          "RHg6UbSjJbdb9qmKM1fTGHKUzL/5pMG6uBU0ywIDAQABAoIBADQkckOIl4IZMUTn\n" +
          "W8LFv6xOdkJwMKC8G6bsPRFbyY+HvC2TLt7epSvfS+f4AcYWaOPcDu2E49vt2sNr\n" +
          "cASly8hgwiRRAB3dHH9vcsboiTo8bi2RFvMqvjv9w3tK2yMxVDtmZamzrrnaV3YV\n" +
          "Q+5nyKo2F/PMDjQ4eUAKDOzjhBuKHsZBTFnA1MFNI+UKj5X4Yp64DFmKlxTX/U2b\n" +
          "wzVywo5hzx2Uhw51jmoLls4YUvMJXD0wW5ZtYRuPogXvXb/of9ef/20/wU11WFKg\n" +
          "Xb4gfR8zUXaXS1sXcnVm3+24vIs9dApUwykuoyjOqxWqcHRec2QT2FxVGkFEraze\n" +
          "CPa4rMECgYEA5Y8CywomIcTgerFGFCeMHJr8nQGqY2V/owFb3k9maczPnC9p4a9R\n" +
          "c5szLxA9FMYFxurQZMBWSEG2JS1HR2mnjigx8UKjYML/A+rvvjZOMe4M6Sy2ggh4\n" +
          "SkLZKpWTzjTe07ByM/j5v/SjNZhWAG7sw4/LmPGRQkwJv+KZhGojuOkCgYEA2cOF\n" +
          "T6cJRv6kvzTz9S0COZOVm+euJh/BXp7oAsAmbNfOpckPMzqHXy8/wpdKl6AAcB57\n" +
          "OuztlNfV1D7qvbz7JuRlYwQ0cEfBgbZPcz1p18HHDXhwn57ZPb8G33Yh9Omg0HNA\n" +
          "Imb4LsVuSqxA6NwSj7cpRekgTedrhLFPJ+Ydb5MCgYEAsM3Q7OjILcIg0t6uht9e\n" +
          "vrlwTsz1mtCV2co2I6crzdj9HeI2vqf1KAElDt6G7PUHhglcr/yjd8uEqmWRPKNX\n" +
          "ddnnfVZB10jYeP/93pac6z/Zmc3iU4yKeUe7U10ZFf0KkiiYDQd59CpLef/2XScS\n" +
          "HB0oRofnxRQjfjLc4muNT+ECgYEAlcDk06MOOTly+F8lCc1bA1dgAmgwFd2usDBd\n" +
          "Y07a3e0HGnGLN3Kfl7C5i0tZq64HvxLnMd2vgLVxQlXGPpdQrC1TH+XLXg+qnlZO\n" +
          "ivSH7i0/gx75bHvj75eH1XK65V8pDVDEoSPottllAIs21CxLw3N1ObOZWJm2EfmR\n" +
          "cuHICmsCgYAtFJ1idqMoHxES3mlRpf2JxyQudP3SCm2WpGmqVzhRYInqeatY5sUd\n" +
          "lPLHm/p77RT7EyxQHTlwn8FJPuM/4ZH1rQd/vB+Y8qAtYJCexDMsbvLW+Js+VOvk\n" +
          "jweEC0nrcL31j9mF0vz5E6tfRu4hhJ6L4yfWs0gSejskeVB/w8QY4g==\n")

        for tpm in self.backEndList:
            if tpm is self.backEndOsx:
                # TODO: Implement TpmBackEndOsx import/export.
                continue

            keyName = Name("/Test/KeyName/KEY/1")
            tpm.deleteKey(keyName)
            self.assertEquals(False, tpm.hasKey(keyName))

            privateKey = TpmPrivateKey()
            privateKeyPkcs1Encoding = Blob(base64.b64decode(privateKeyPkcs1Base64))
            privateKey.loadPkcs1(privateKeyPkcs1Encoding.buf())

            password = Blob("password").toBytes()
            encryptedPkcs8 = privateKey.toEncryptedPkcs8(password)

            tpm.importKey(keyName, encryptedPkcs8.buf(), password)
            self.assertEquals(True, tpm.hasKey(keyName))
            try:
                # Can't import the same keyName again.
                tpm.importKey(keyName, encryptedPkcs8.buf(), password)
                self.fail("Did not throw the expected exception")
            except TpmBackEnd.Error:
                pass
            else:
                self.fail("Did not throw the expected exception")

            exportedKey = tpm.exportKey(keyName, password)
            self.assertEquals(True, tpm.hasKey(keyName))

            privateKey2 = TpmPrivateKey()
            privateKey2.loadEncryptedPkcs8(exportedKey.buf(), password)
            privateKey2Pkcs1Encoding = privateKey2.toPkcs1()
            self.assertTrue(privateKeyPkcs1Encoding.equals(privateKey2Pkcs1Encoding))

            tpm.deleteKey(keyName)
            self.assertEquals(False, tpm.hasKey(keyName))
            try:
                tpm.exportKey(keyName, password)
                self.fail("Did not throw the expected exception")
            except TpmBackEnd.Error:
                pass
            else:
                self.fail("Did not throw the expected exception")
예제 #3
0
    class Component(object):
        """
        Create a new Name.Component.
        
        :param value: (optional) If value is already a Blob or Name.Component,
          then take another pointer to the value.  Otherwise, create a new
          Blob with a copy of the value.  If omitted, create an empty component.
        :type value: Blob or Name.Component or value for Blob constructor
        """
        def __init__(self, value = None):
            if type(value) is Name.Component:
                # Use the existing Blob in the other Component.
                self._value = value._value
            elif value == None:
                self._value = Blob([])
            else:
                # Blob will make a copy.
                self._value = value if isinstance(value, Blob) else Blob(value)
            
        def getValue(self):
            """
            Get the value of the component.

            :return: The component value.
            :rtype: Blob
            """
            return self._value
        
        def toEscapedString(self, result = None):
            """
            Convert this component to a string, escaping characters according
            to the NDN URI Scheme. This also adds "..." to a value with zero or
            more ".".

            :param BytesIO result: (optional) The BytesIO stream to write to.  
              If omitted, return a str with the result.
            :return: The result as a string (only if result is omitted).
            :rtype: str
            """
            if result == None:
                return Name.toEscapedString(self._value.buf())
            else:
                Name.toEscapedString(self._value.buf(), result)

        def toNumber(self):
            """
            Interpret this name component as a network-ordered number and return 
            an integer.
            
            :return: The integer number.
            :rtype: int
            """
            result = 0
            for i in range(self._value.size()):
                result *= 256
                result += self._value.buf()[i]
            return result
        
        def toNumberWithMarker(self, marker):
            """
            Interpret this name component as a network-ordered number with a 
            marker and return an integer.
            
            :param int marker: The required first byte of the component.
            :return: The integer number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component does not 
              equal the marker.
            """
            if self._value.size() <= 0 or self._value.buf()[0] != marker:
                raise RuntimeError(
                       "Name component does not begin with the expected marker")

            result = 0
            for i in range(1, self._value.size()):
                result *= 256
                result += self._value.buf()[i]
            return result
        
        def toSegment(self):
            """
            Interpret this name component as a segment number according to NDN
            naming conventions for "Segment number" (marker 0x00).
            http://named-data.net/doc/tech-memos/naming-conventions.pdf
            
            :return: The integer segment number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the 
              expected marker.
            """
            return self.toNumberWithMarker(0x00)

        def toSegmentOffset(self):
            """
            Interpret this name component as a segment byte offset according to
            NDN naming conventions for segment "Byte offset" (marker 0xFB).
            http://named-data.net/doc/tech-memos/naming-conventions.pdf

            :return: The integer segment byte offset.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the
              expected marker.
            """
            return self.toNumberWithMarker(0xFB)
        
        def toVersion(self):
            """
            Interpret this name component as a version number  according to NDN
            naming conventions for "Versioning" (marker 0xFD). Note that this
            returns the exact number from the component without converting it to
            a time representation.
            http://named-data.net/doc/tech-memos/naming-conventions.pdf
            
            :return: The integer version number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the 
              expected marker.
            """
            return self.toNumberWithMarker(0xFD)

        def toTimestamp(self):
            """
            Interpret this name component as a timestamp  according to NDN naming
            conventions for "Timestamp" (marker 0xFC).
            http://named-data.net/doc/tech-memos/naming-conventions.pdf

            :return: The number of microseconds since the UNIX epoch (Thursday,
              1 January 1970) not counting leap seconds.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the
              expected marker.
            """
            return self.toNumberWithMarker(0xFC)

        def toSequenceNumber(self):
            """
            Interpret this name component as a sequence number according to NDN
            naming conventions for "Sequencing" (marker 0xFE).
            http://named-data.net/doc/tech-memos/naming-conventions.pdf

            :return: The integer sequence number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the
              expected marker.
            """
            return self.toNumberWithMarker(0xFE)
        
        def equals(self, other):
            """
            Check if this is the same component as other.
            
            :param Name.Component other: The other Component to compare with.
            :return: True if the components are equal, otherwise False.
            :rtype: bool
            """
            return self._value.equals(other._value)
        
        def compare(self, other):
            """
            Compare this to the other Component using NDN canonical ordering.
            
            :param Name.Component other: The other Component to compare with.
            :return: 0 If they compare equal, -1 if self comes before other in 
              the canonical ordering, or 1 if self comes after other in the 
              canonical ordering.
            :rtype: int
            :see: http://named-data.net/doc/0.2/technical/CanonicalOrder.html
            """
            if self._value.size() < other._value.size():
                return -1
            if self._value.size() > other._value.size():
                return 1

            # The components are equal length. Just do a byte compare.
            return self._value.compare(other._value)
        
        @staticmethod
        def fromNumber(number):
            """
            Create a component whose value is the nonNegativeInteger encoding of
            the number.
            
            :param int number: The number to be encoded.
            :return: The component value.
            :rtype: Name.Component
            """
            encoder = TlvEncoder(8)
            encoder.writeNonNegativeInteger(number)
            return Name.Component(Blob(encoder.getOutput(), False))
        
        @staticmethod
        def fromNumberWithMarker(number, marker):
            """
            Create a component whose value is the marker appended with the 
            nonNegativeInteger encoding of the number.

            :param int number: The number to be encoded.
            :param int marker: The marker to use as the first byte of the 
              component.
            :return: The component value.
            :rtype: Name.Component
            """
            encoder = TlvEncoder(9)
            # Encode backwards.
            encoder.writeNonNegativeInteger(number)
            encoder.writeNonNegativeInteger(marker)
            return Name.Component(Blob(encoder.getOutput(), False))

        # Python operators
        
        def __eq__(self, other):
            return type(other) is Name.Component and self.equals(other)
        
        def __ne__(self, other):
            return not self == other

        def __le__(self, other):
            return self.compare(other) <= 0

        def __lt__(self, other):
            return self.compare(other) < 0

        def __ge__(self, other):
            return self.compare(other) >= 0

        def __gt__(self, other):
            return self.compare(other) > 0

        def __len__(self):
            return self._value.size()
예제 #4
0
    def setUp(self):
        # Reuse the policy_config subdirectory for the temporary SQLite files.
        self.dKeyDatabaseFilePath = "policy_config/manager-d-key-test.db"
        try:
            os.remove(self.dKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.eKeyDatabaseFilePath = "policy_config/manager-e-key-test.db"
        try:
            os.remove(self.eKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.intervalDatabaseFilePath = "policy_config/manager-interval-test.db"
        try:
            os.remove(self.intervalDatabaseFilePath)
        except OSError:
            # no such file
            pass

        self.groupKeyDatabaseFilePath = "policy_config/manager-group-key-test.db"
        try:
            os.remove(self.groupKeyDatabaseFilePath)
        except OSError:
            # no such file
            pass

        params = RsaKeyParams()
        memberDecryptKey = RsaAlgorithm.generateKey(params)
        self.decryptKeyBlob = memberDecryptKey.getKeyBits()
        memberEncryptKey = RsaAlgorithm.deriveEncryptKey(self.decryptKeyBlob)
        self.encryptKeyBlob = memberEncryptKey.getKeyBits()

        # Generate the certificate.
        self.certificate = IdentityCertificate()
        self.certificate.setName(Name("/ndn/memberA/KEY/ksk-123/ID-CERT/123"))
        contentPublicKey = PublicKey(self.encryptKeyBlob)
        self.certificate.setPublicKeyInfo(contentPublicKey)
        self.certificate.setNotBefore(0)
        self.certificate.setNotAfter(0)
        self.certificate.encode()

        signatureInfoBlob = Blob(SIG_INFO, False)
        signatureValueBlob = Blob(SIG_VALUE, False)

        signature = TlvWireFormat.get().decodeSignatureInfoAndValue(
          signatureInfoBlob.buf(), signatureValueBlob.buf())
        self.certificate.setSignature(signature)

        self.certificate.wireEncode()

        # Set up the keyChain.
        identityStorage = MemoryIdentityStorage()
        privateKeyStorage = MemoryPrivateKeyStorage()
        self.keyChain = KeyChain(
          IdentityManager(identityStorage, privateKeyStorage),
          NoVerifyPolicyManager())
        identityName = Name("TestGroupManager")
        self.keyChain.createIdentityAndCertificate(identityName)
        self.keyChain.getIdentityManager().setDefaultIdentity(identityName)
예제 #5
0
    def test_import_export(self):
        privateKeyPkcs1Base64 = (
          "MIIEpAIBAAKCAQEAw0WM1/WhAxyLtEqsiAJgWDZWuzkYpeYVdeeZcqRZzzfRgBQT\n" +
          "sNozS5t4HnwTZhwwXbH7k3QN0kRTV826Xobws3iigohnM9yTK+KKiayPhIAm/+5H\n" +
          "GT6SgFJhYhqo1/upWdueojil6RP4/AgavHhopxlAVbk6G9VdVnlQcQ5Zv0OcGi73\n" +
          "c+EnYD/YgURYGSngUi/Ynsh779p2U69/te9gZwIL5PuE9BiO6I39cL9z7EK1SfZh\n" +
          "OWvDe/qH7YhD/BHwcWit8FjRww1glwRVTJsA9rH58ynaAix0tcR/nBMRLUX+e3rU\n" +
          "RHg6UbSjJbdb9qmKM1fTGHKUzL/5pMG6uBU0ywIDAQABAoIBADQkckOIl4IZMUTn\n" +
          "W8LFv6xOdkJwMKC8G6bsPRFbyY+HvC2TLt7epSvfS+f4AcYWaOPcDu2E49vt2sNr\n" +
          "cASly8hgwiRRAB3dHH9vcsboiTo8bi2RFvMqvjv9w3tK2yMxVDtmZamzrrnaV3YV\n" +
          "Q+5nyKo2F/PMDjQ4eUAKDOzjhBuKHsZBTFnA1MFNI+UKj5X4Yp64DFmKlxTX/U2b\n" +
          "wzVywo5hzx2Uhw51jmoLls4YUvMJXD0wW5ZtYRuPogXvXb/of9ef/20/wU11WFKg\n" +
          "Xb4gfR8zUXaXS1sXcnVm3+24vIs9dApUwykuoyjOqxWqcHRec2QT2FxVGkFEraze\n" +
          "CPa4rMECgYEA5Y8CywomIcTgerFGFCeMHJr8nQGqY2V/owFb3k9maczPnC9p4a9R\n" +
          "c5szLxA9FMYFxurQZMBWSEG2JS1HR2mnjigx8UKjYML/A+rvvjZOMe4M6Sy2ggh4\n" +
          "SkLZKpWTzjTe07ByM/j5v/SjNZhWAG7sw4/LmPGRQkwJv+KZhGojuOkCgYEA2cOF\n" +
          "T6cJRv6kvzTz9S0COZOVm+euJh/BXp7oAsAmbNfOpckPMzqHXy8/wpdKl6AAcB57\n" +
          "OuztlNfV1D7qvbz7JuRlYwQ0cEfBgbZPcz1p18HHDXhwn57ZPb8G33Yh9Omg0HNA\n" +
          "Imb4LsVuSqxA6NwSj7cpRekgTedrhLFPJ+Ydb5MCgYEAsM3Q7OjILcIg0t6uht9e\n" +
          "vrlwTsz1mtCV2co2I6crzdj9HeI2vqf1KAElDt6G7PUHhglcr/yjd8uEqmWRPKNX\n" +
          "ddnnfVZB10jYeP/93pac6z/Zmc3iU4yKeUe7U10ZFf0KkiiYDQd59CpLef/2XScS\n" +
          "HB0oRofnxRQjfjLc4muNT+ECgYEAlcDk06MOOTly+F8lCc1bA1dgAmgwFd2usDBd\n" +
          "Y07a3e0HGnGLN3Kfl7C5i0tZq64HvxLnMd2vgLVxQlXGPpdQrC1TH+XLXg+qnlZO\n" +
          "ivSH7i0/gx75bHvj75eH1XK65V8pDVDEoSPottllAIs21CxLw3N1ObOZWJm2EfmR\n" +
          "cuHICmsCgYAtFJ1idqMoHxES3mlRpf2JxyQudP3SCm2WpGmqVzhRYInqeatY5sUd\n" +
          "lPLHm/p77RT7EyxQHTlwn8FJPuM/4ZH1rQd/vB+Y8qAtYJCexDMsbvLW+Js+VOvk\n" +
          "jweEC0nrcL31j9mF0vz5E6tfRu4hhJ6L4yfWs0gSejskeVB/w8QY4g==\n")

        for tpm in self.backEndList:
            if tpm is self.backEndOsx:
                # TODO: Implement TpmBackEndOsx import/export.
                continue

            keyName = Name("/Test/KeyName/KEY/1")
            tpm.deleteKey(keyName)
            self.assertEqual(False, tpm.hasKey(keyName))

            privateKey = TpmPrivateKey()
            privateKeyPkcs1Encoding = Blob(base64.b64decode(privateKeyPkcs1Base64))
            privateKey.loadPkcs1(privateKeyPkcs1Encoding.buf())

            password = Blob("password").toBytes()
            encryptedPkcs8 = privateKey.toEncryptedPkcs8(password)

            tpm.importKey(keyName, encryptedPkcs8.buf(), password)
            self.assertEqual(True, tpm.hasKey(keyName))
            try:
                # Can't import the same keyName again.
                tpm.importKey(keyName, encryptedPkcs8.buf(), password)
                self.fail("Did not throw the expected exception")
            except TpmBackEnd.Error:
                pass
            else:
                self.fail("Did not throw the expected exception")

            exportedKey = tpm.exportKey(keyName, password)
            self.assertEqual(True, tpm.hasKey(keyName))

            privateKey2 = TpmPrivateKey()
            privateKey2.loadEncryptedPkcs8(exportedKey.buf(), password)
            privateKey2Pkcs1Encoding = privateKey2.toPkcs1()
            self.assertTrue(privateKeyPkcs1Encoding.equals(privateKey2Pkcs1Encoding))

            tpm.deleteKey(keyName)
            self.assertEqual(False, tpm.hasKey(keyName))
            try:
                tpm.exportKey(keyName, password)
                self.fail("Did not throw the expected exception")
            except TpmBackEnd.Error:
                pass
            else:
                self.fail("Did not throw the expected exception")
예제 #6
0
    class Component(object):
        """
        Create a new Name.Component.
        
        :param value: (optional) If value is already a Blob or Name.Component,
          then take another pointer to the value.  Otherwise, create a new
          Blob with a copy of the value.  If omitted, create an empty component.
        :type value: Blob or Name.Component or value for Blob constructor
        """
        def __init__(self, value = None):
            if type(value) is Name.Component:
                # Use the existing Blob in the other Component.
                self._value = value._value
            elif value == None:
                self._value = Blob([])
            else:
                # Blob will make a copy.
                self._value = value if isinstance(value, Blob) else Blob(value)
            
        def getValue(self):
            """
            Get the value of the component.

            :return: The component value.
            :rtype: Blob
            """
            return self._value
        
        def toEscapedString(self, result = None):
            """
            Convert this component to a string, escaping characters according
            to the NDN URI Scheme. This also adds "..." to a value with zero or
            more ".".

            :param BytesIO result: (optional) The BytesIO stream to write to.  
              If omitted, return a str with the result.
            :return: The result as a string (only if result is omitted).
            :rtype: str
            """
            if result == None:
                return Name.toEscapedString(self._value.buf())
            else:
                Name.toEscapedString(self._value.buf(), result)

        def toNumber(self):
            """
            Interpret this name component as a network-ordered number and return 
            an integer.
            
            :return: The integer number.
            :rtype: int
            """
            result = 0
            for i in range(self._value.size()):
                result *= 256
                result += self._value.buf()[i]
            return result
        
        def toNumberWithMarker(self, marker):
            """
            Interpret this name component as a network-ordered number with a 
            marker and return an integer.
            
            :param int marker: The required first byte of the component.
            :return: The integer number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component does not 
              equal the marker.
            """
            if self._value.size() <= 0 or self._value.buf()[0] != marker:
                raise RuntimeError(
                       "Name component does not begin with the expected marker")

            result = 0
            for i in range(1, self._value.size()):
                result *= 256
                result += self._value.buf()[i]
            return result
        
        def toSegment(self):
            """
            Interpret this name component as a segment number according to NDN 
            name conventions (a network-ordered number where the first byte is 
            the marker 0x00).
            
            :return: The integer segment number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the 
              expected marker.
            """
            return self.toNumberWithMarker(0x00)
        
        def toVersion(self):
            """
            Interpret this name component as a version number according to NDN 
            name conventions (a network-ordered number where the first byte is 
            the marker 0xFD).  Note that this returns the exact number from the 
            component without converting it to a time representation.
            
            :return: The integer version number.
            :rtype: int
            :raises RuntimeError: If the first byte of the component is not the 
              expected marker.
            """
            return self.toNumberWithMarker(0xFD)
        
        def equals(self, other):
            """
            Check if this is the same component as other.
            
            :param Name.Component other: The other Component to compare with.
            :return: True if the components are equal, otherwise False.
            :rtype: bool
            """
            return self._value.equals(other._value)
        
        def compare(self, other):
            """
            Compare this to the other Component using NDN canonical ordering.
            
            :param Name.Component other: The other Component to compare with.
            :return: 0 If they compare equal, -1 if self comes before other in 
              the canonical ordering, or 1 if self comes after other in the 
              canonical ordering.
            :rtype: int
            :see: http://named-data.net/doc/0.2/technical/CanonicalOrder.html
            """
            if self._value.size() < other._value.size():
                return -1
            if self._value.size() > other._value.size():
                return 1

            # The components are equal length. Just do a byte compare.
            return self._value.compare(other._value)
        
        @staticmethod
        def fromNumber(number):
            """
            Create a component whose value is the network-ordered encoding of 
            the number. Note: if the number is zero, the result is empty.
            
            :param int number: The number to be encoded.
            :return: The component value.
            :rtype: Name.Component
            """
            value = []

            # First encode in little endian.
            while number != 0:
                value.append(number & 0xff)
                number >>= 8
                
            # Make it big endian.
            value.reverse()
            return Name.Component(Blob(value, False))
        
        @staticmethod
        def fromNumberWithMarker(number, marker):
            """
            Create a component whose value is the marker appended with the 
            network-ordered encoding of the number. Note: if the number is zero, 
            no bytes are used for the number - the result will have only the 
            marker.

            :param int number: The number to be encoded.
            :param int marker: The marker to use as the first byte of the 
              component.
            :return: The component value.
            :rtype: Name.Component
            """
            value = []

            # First encode in little endian.
            while number != 0:
                value.append(number & 0xff)
                number >>= 8
                
            # Make it big endian.
            value.reverse()
            
            # Prepend the leading marker.
            value.insert(0, marker)
            
            return Name.Component(Blob(value, False))

        # Python operators
        
        def __eq__(self, other):
            return type(other) is Name.Component and self.equals(other)
        
        def __ne__(self, other):
            return not self == other

        def __le__(self, other):
            return self.compare(other) <= 0

        def __lt__(self, other):
            return self.compare(other) < 0

        def __ge__(self, other):
            return self.compare(other) >= 0

        def __gt__(self, other):
            return self.compare(other) > 0