Add ed25519 signing support to imgtool
This adds ed25519 signature support using the "prehash" method. Instead
of using the direct contents of the image and header payloads, a sha256
is generated and signed (SHA256-Ed25519). This allows for compatibility
with already existing tools that use the sha256 hash, like mcumgr, etc.
Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/scripts/imgtool/keys/ed25519_test.py b/scripts/imgtool/keys/ed25519_test.py
new file mode 100644
index 0000000..6ed3656
--- /dev/null
+++ b/scripts/imgtool/keys/ed25519_test.py
@@ -0,0 +1,96 @@
+"""
+Tests for ECDSA keys
+"""
+
+import io
+import os.path
+import sys
+import tempfile
+import unittest
+
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives.asymmetric import ed25519
+
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../..')))
+
+from imgtool.keys import load, Ed25519, Ed25519UsageError
+
+
+class Ed25519KeyGeneration(unittest.TestCase):
+
+ def setUp(self):
+ self.test_dir = tempfile.TemporaryDirectory()
+
+ def tname(self, base):
+ return os.path.join(self.test_dir.name, base)
+
+ def tearDown(self):
+ self.test_dir.cleanup()
+
+ def test_keygen(self):
+ name1 = self.tname("keygen.pem")
+ k = Ed25519.generate()
+ k.export_private(name1, b'secret')
+
+ self.assertIsNone(load(name1))
+
+ k2 = load(name1, b'secret')
+
+ pubname = self.tname('keygen-pub.pem')
+ k2.export_public(pubname)
+ pk2 = load(pubname)
+
+ # We should be able to export the public key from the loaded
+ # public key, but not the private key.
+ pk2.export_public(self.tname('keygen-pub2.pem'))
+ self.assertRaises(Ed25519UsageError,
+ pk2.export_private, self.tname('keygen-priv2.pem'))
+
+ def test_emit(self):
+ """Basic sanity check on the code emitters."""
+ k = Ed25519.generate()
+
+ ccode = io.StringIO()
+ k.emit_c(ccode)
+ self.assertIn("ed25519_pub_key", ccode.getvalue())
+ self.assertIn("ed25519_pub_key_len", ccode.getvalue())
+
+ rustcode = io.StringIO()
+ k.emit_rust(rustcode)
+ self.assertIn("ED25519_PUB_KEY", rustcode.getvalue())
+
+ def test_emit_pub(self):
+ """Basic sanity check on the code emitters."""
+ pubname = self.tname("public.pem")
+ k = Ed25519.generate()
+ k.export_public(pubname)
+
+ k2 = load(pubname)
+
+ ccode = io.StringIO()
+ k2.emit_c(ccode)
+ self.assertIn("ed25519_pub_key", ccode.getvalue())
+ self.assertIn("ed25519_pub_key_len", ccode.getvalue())
+
+ rustcode = io.StringIO()
+ k2.emit_rust(rustcode)
+ self.assertIn("ED25519_PUB_KEY", rustcode.getvalue())
+
+ def test_sig(self):
+ k = Ed25519.generate()
+ buf = b'This is the message'
+ sig = k.raw_sign(buf)
+
+ # The code doesn't have any verification, so verify this
+ # manually.
+ k.key.public_key().verify(signature=sig, data=buf)
+
+ # Modify the message to make sure the signature fails.
+ self.assertRaises(InvalidSignature,
+ k.key.public_key().verify,
+ signature=sig,
+ data=b'This is thE message')
+
+
+if __name__ == '__main__':
+ unittest.main()