Use pskcxml as file name extension

This is the extension that is suggested in RFC6030.

README

@@ -23,7 +23,7 @@ parsing existing PSKC files.
 Extracting key matarial from PSKC files is as simple as.
 
 >>> from pskc import PSKC
->>> pskc = PSKC('tests/rfc6030-figure7.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure7.pskcxml')
 >>> pskc.encryption.derive_key('qwerty')
 >>> for key in pskc.keys:
 ...     print key.serial, key.secret

pskc/__init__.py

@@ -31,7 +31,7 @@
 The following prints all keys, decrypting using a password:
 
 >>> from pskc import PSKC
->>> pskc = PSKC('tests/rfc6030-figure7.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure7.pskcxml')
 >>> pskc.encryption.derive_key('qwerty')
 >>> for key in pskc.keys:
 ...     print key.serial, key.secret

tests/test_rfc6030.doctest

@@ -24,7 +24,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 This tests Figure 2 from RFC6030. It is a basic key container example with
 a simple plain text secret key.
 
->>> pskc = PSKC('tests/rfc6030-figure2.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure2.pskcxml')
 >>> [key.secret for key in pskc.keys]
 ['1234']
 >>> key = pskc.keys[0]
@@ -42,7 +42,7 @@ This tests Figure 3 from RFC6030. Relative to Figure 2 this includes
 device, cryptographic module and user identification as well as some more
 parameters.
 
->>> pskc = PSKC('tests/rfc6030-figure3.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure3.pskcxml')
 >>> pskc.id
 'exampleID1'
 >>> key = pskc.keys[0]
@@ -76,7 +76,7 @@ This tests Figure 4 from RFC6030. In this case the key value itself is not
 contained but can be derived using the serial and out-of-band agreements
 on the meanings of key_profile and key_reference.
 
->>> pskc = PSKC('tests/rfc6030-figure4.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure4.pskcxml')
 >>> key = pskc.keys[0]
 >>> key.serial
 '987654321'
@@ -90,7 +90,7 @@ on the meanings of key_profile and key_reference.
 
 This tests the key policy properties as illustrated in Figure 5 from RFC6030.
 
->>> pskc = PSKC('tests/rfc6030-figure5.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure5.pskcxml')
 >>> len(pskc.keys)
 2
 >>> key1, key2 = pskc.keys
@@ -144,7 +144,7 @@ This tests key encryption based on pre-shared keys as illustrated in
 Figure 6 from RFC6030. The first attempt at extracting the key will fail
 due to the encryption.
 
->>> pskc = PSKC('tests/rfc6030-figure6.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure6.pskcxml')
 >>> key = pskc.keys[0]
 >>> key.id
 '12345678'
@@ -164,7 +164,7 @@ True
 This tests a derived master key using PBKDF2 as seen in Figure 7 from
 RFC6030.
 
->>> pskc = PSKC('tests/rfc6030-figure7.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure7.pskcxml')
 >>> pskc.encryption.key_name
 'My Password 1'
 >>> pskc.encryption.derive_key('qwerty')
@@ -181,7 +181,7 @@ True
 
 This tests bulk provisioning as shown in Figure 10 From RFC6030.
 
->>> pskc = PSKC('tests/rfc6030-figure10.pskc')
+>>> pskc = PSKC('tests/rfc6030-figure10.pskcxml')
 >>> all(key.manufacturer == 'TokenVendorAcme' for key in pskc.keys)
 True
 >>> [key.serial for key in pskc.keys]