diff --git a/borg/testsuite/convert.py b/borg/testsuite/convert.py
index e201581c3..ba3af8ee6 100644
--- a/borg/testsuite/convert.py
+++ b/borg/testsuite/convert.py
@@ -5,16 +5,27 @@ import shutil
 import tempfile
 
 import attic.repository
+import attic.key
+import attic.helpers
 
-from ..helpers import IntegrityError
+from ..helpers import IntegrityError, get_keys_dir
 from ..repository import Repository, MAGIC
+from ..key import KeyfileKey, KeyfileNotFoundError
 from . import BaseTestCase
 
 class NotImplementedException(Exception):
     pass
 
+class AtticKeyfileKey(KeyfileKey):
+    '''backwards compatible Attick key file parser'''
+    FILE_ID = 'ATTIC KEY'
+
 class ConversionTestCase(BaseTestCase):
 
+    class MockArgs:
+        def __init__(self, path):
+            self.repository = attic.helpers.Location(path)
+
     def open(self, path, repo_type  = Repository, create=False):
         return repo_type(os.path.join(path, 'repository'), create = create)
 
@@ -26,6 +37,10 @@ class ConversionTestCase(BaseTestCase):
         # throw some stuff in that repo, copied from `RepositoryTestCase.test1`_
         for x in range(100):
             self.attic_repo.put(('%-32d' % x).encode('ascii'), b'SOMEDATA')
+        self.keysdir = self.MockArgs(self.tmppath)
+        os.environ['ATTIC_KEYS_DIR'] = self.tmppath
+        os.environ['ATTIC_PASSPHRASE'] = 'test'
+        self.key = attic.key.KeyfileKey.create(self.attic_repo, self.keysdir)
         self.attic_repo.close()
 
     def test_convert(self):
@@ -33,9 +48,15 @@ class ConversionTestCase(BaseTestCase):
         # check should fail because of magic number
         assert not self.repository.check() # can't check raises() because check() handles the error
         self.repository.close()
+        os.environ['BORG_KEYS_DIR'] = self.tmppath
         self.convert()
+        # check that the new keyfile is alright
+        keyfile = os.path.join(get_keys_dir(),
+                               os.path.basename(self.key.path))
+        with open(keyfile, 'r') as f:
+            assert f.read().startswith(KeyfileKey.FILE_ID)
         self.repository = self.open(self.tmppath)
-        assert self.repository.check() # can't check raises() because check() handles the error
+        assert self.repository.check()
         self.repository.close()
 
     def convert(self):
@@ -45,32 +66,52 @@ class ConversionTestCase(BaseTestCase):
         important to least important: segments, key files, and various
         caches, the latter being optional, as they will be rebuilt if
         missing.'''
-        self.convert_segments()
-        with pytest.raises(NotImplementedException):
-            self.convert_keyfiles()
+        self.repository = self.open(self.tmppath)
+        segments = [ filename for i, filename in self.repository.io.segment_iterator() ]
+        try:
+            keyfile = self.find_attic_keyfile()
+        except KeyfileNotFoundError:
+            print("no key file found for repository, not converting")
+        else:
+            self.convert_keyfiles(keyfile)
+        self.repository.close()
+        self.convert_segments(segments)
         with pytest.raises(NotImplementedException):
             self.convert_cache()
 
-    def convert_segments(self):
+    def convert_segments(self, segments):
         '''convert repository segments from attic to borg
 
         replacement pattern is `s/ATTICSEG/BORG_SEG/` in files in
         `$ATTIC_REPO/data/**`.
 
         luckily the segment length didn't change so we can just
-        replace the 8 first bytes of all regular files in there.
-
-        `Repository.segment_iterator()` could be used here.'''
-        self.repository = self.open(self.tmppath)
-        segs = [ filename for i, filename in self.repository.io.segment_iterator() ]
-        self.repository.close()
-        for filename in segs:
+        replace the 8 first bytes of all regular files in there.'''
+        for filename in segments:
             print("converting segment %s..." % filename)
             with open(filename, 'r+b') as segment:
                 segment.seek(0)
                 segment.write(MAGIC)
 
-    def convert_keyfiles(self):
+    def find_attic_keyfile(self):
+        '''find the attic keyfiles
+
+        this is expected to look into $HOME/.attic/keys or
+        $ATTIC_KEYS_DIR for key files matching the given Borg
+        repository.
+
+        it is expected to raise an exception (KeyfileNotFoundError) if
+        no key is found. whether that exception is from Borg or Attic
+        is unclear.
+
+        this is split in a separate function in case we want to
+        reimplement the attic code here.
+        '''
+        self.repository._location = attic.helpers.Location(self.tmppath)
+        return attic.key.KeyfileKey().find_key_file(self.repository)
+
+    def convert_keyfiles(self, keyfile):
+
         '''convert key files from attic to borg
 
         replacement pattern is `s/ATTIC KEY/BORG_KEY/` in
@@ -82,7 +123,20 @@ class ConversionTestCase(BaseTestCase):
         finds the keys with the right identifier for the repo, no need
         to decrypt to convert. will need to rewrite the whole key file
         because magic number length changed.'''
-        raise NotImplementedException('not implemented')
+        print("converting keyfile %s" % keyfile)
+        with open(keyfile, 'r') as f:
+            data = f.read()
+        data = data.replace(AtticKeyfileKey.FILE_ID,
+                            KeyfileKey.FILE_ID,
+                            1)
+        keyfile = os.path.join(get_keys_dir(),
+                               os.path.basename(keyfile))
+        print("writing borg keyfile to %s" % keyfile)
+        with open(keyfile, 'w') as f:
+            f.write(data)
+        with open(keyfile, 'r') as f:
+            data = f.read()
+        assert data.startswith(KeyfileKey.FILE_ID)
 
     def convert_cache(self):
         '''convert caches from attic to borg