The test

src/tests/samples.py

@@ -2,6 +2,11 @@
 
 from binascii import unhexlify
 
+# hello, page 1 of the Specification
+sample_double_sha512 = unhexlify(
+    '0592a10584ffabf96539f3d780d776828c67da1ab5b169e9e8aed838aaecc9ed36d49ff14'
+    '23c55f019e050c66c6324f53588be88894fef4dcffdb74b98e2b200')
+
 
 magic = 0xE9BEB4D9
 

src/tests/test_crypto.py

@@ -16,6 +16,7 @@ except ImportError:
     RIPEMD = None
 
 from .samples import (
+    sample_double_sha512,
     sample_msg, sample_pubsigningkey, sample_pubencryptionkey,
     sample_privsigningkey, sample_privencryptionkey, sample_ripe,
     sample_sig, sample_sig_sha1
@@ -68,6 +69,11 @@ class TestHighlevelcrypto(unittest.TestCase):
     #     self.assertEqual(
     #         highlevelcrypto.sign(sample_msg, sample_privsigningkey), sample_sig)
 
+    def test_double_sha512(self):
+        """Reproduce the example on page 1 of the Specification"""
+        self.assertEqual(
+            highlevelcrypto.double_sha512(b'hello'), sample_double_sha512)
+
     def test_verify(self):
         """Verify sample signatures and newly generated ones"""
         pubkey_hex = hexlify(sample_pubsigningkey)