add some HKDF tests while we're still using a local copy

tests/test_hkdf.py

@@ -0,0 +1,52 @@
+from __future__ import print_function
+import unittest
+from binascii import hexlify, unhexlify
+from wormhole.hkdf import HKDF
+#from hkdf import Hkdf
+
+def generate_KAT():
+    print("KAT = [")
+    for salt in (None, b"", b"salt"):
+        for context in (b"", b"context"):
+            skm = b"secret"
+            out = HKDF(skm, 64, XTS=salt, CTXinfo=context)
+            hexout = "  '%s' +\n  '%s'" % (hexlify(out[:32]),
+                                           hexlify(out[32:]))
+            print(" (%r, %r, %r,\n%s)," % (salt, context, skm, hexout))
+    print("]")
+
+KAT = [
+ (None, '', 'secret',
+  '2f34e5ff91ec85d53ca9b543683174d0cf550b60d5f52b24c97b386cfcf6cbbf' +
+  '9cfd42fd37e1e5a214d15f03058d7fee63dc28f564b7b9fe3da514f80daad4bf'),
+ (None, 'context', 'secret',
+  'c24c303a1adfb4c3e2b092e6254ed481c41d8955ba8ec3f6a1473493a60c957b' +
+  '31b723018ca75557214d3d5c61c0c7a5315b103b21ff00cb03ebe023dc347a47'),
+ ('', '', 'secret',
+  '2f34e5ff91ec85d53ca9b543683174d0cf550b60d5f52b24c97b386cfcf6cbbf' +
+  '9cfd42fd37e1e5a214d15f03058d7fee63dc28f564b7b9fe3da514f80daad4bf'),
+ ('', 'context', 'secret',
+  'c24c303a1adfb4c3e2b092e6254ed481c41d8955ba8ec3f6a1473493a60c957b' +
+  '31b723018ca75557214d3d5c61c0c7a5315b103b21ff00cb03ebe023dc347a47'),
+ ('salt', '', 'secret',
+  'f1156507c39b0e326159e778696253122de430899a8df2484040a85a5f95ceb1' +
+  'dfca555d4cc603bdf7153ed1560de8cbc3234b27a6d2be8e8ca202d90649679a'),
+ ('salt', 'context', 'secret',
+  '61a4f201a867bcc12381ddb180d27074408d03ee9d5750855e5a12d967fa060f' +
+  '10336ead9370927eaabb0d60b259346ee5f57eb7ceba8c72f1ed3f2932b1bf19'),
+]
+
+class TestKAT(unittest.TestCase):
+    # note: this uses SHA256
+    def test_kat(self):
+        for (salt, context, skm, expected_hexout) in KAT:
+            expected_out = unhexlify(expected_hexout)
+            for outlen in range(0, len(expected_out)):
+                out = HKDF(skm, outlen, XTS=salt, CTXinfo=context)
+                self.assertEqual(out, expected_out[:outlen])
+                #out = Hkdf(salt, skm).expand(context, outlen)
+                #self.assertEqual(out, expected_out[:outlen])
+
+if __name__ == '__main__':
+    generate_KAT()
+