Add age plugin support

See https://github.com/str4d/rage/tree/main/age-plugin.

Example usage:

	RAGE_DIR=$PWD/../Rust/rage
	(cd $RAGE_DIR; cargo build --all)
	export PATH=$PATH:$RAGE_DIR/target/debug

	age-plugin-trezor -i "John Doe" | tee trezor.id
	R=$(grep recipient trezor.id | cut -f 3 -d ' ')

	date | tee msg.txt
	rage -er $R < msg.txt > enc.txt
	rage -di trezor.id < enc.txt

libagent/device/trezor.py

@@ -126,6 +126,11 @@ class Trezor(interface.Device):
 
     def ecdh(self, identity, pubkey):
         """Get shared session key using Elliptic Curve Diffie-Hellman."""
+        session_key, _ = self.ecdh_with_pubkey(identity, pubkey)
+        return session_key
+
+    def ecdh_with_pubkey(self, identity, pubkey):
+        """Get shared session key using Elliptic Curve Diffie-Hellman & self public key."""
         curve_name = identity.get_curve_name(ecdh=True)
         log.debug('"%s" shared session key (%s) for %r from %s',
                   identity.to_string(), curve_name, pubkey, self)
@@ -138,7 +143,11 @@ class Trezor(interface.Device):
             log.debug('result: %s', result)
             assert len(result.session_key) in {65, 33}  # NIST256 or Curve25519
             assert result.session_key[:1] == b'\x04'
-            return bytes(result.session_key)
+            self_pubkey = result.public_key
+            if self_pubkey:
+                self_pubkey = bytes(self_pubkey[1:])
+
+            return bytes(result.session_key), self_pubkey
         except self._defs.TrezorFailure as e:
             msg = '{} error: {}'.format(self, e)
             log.debug(msg, exc_info=True)

libagent/device/trezor_defs.py

@@ -1,12 +1,11 @@
 """TREZOR-related definitions."""
 
-import logging
 # pylint: disable=unused-import,import-error,no-name-in-module,no-member
+import logging
 import os
 
 import mnemonic
 import semver
-
 import trezorlib
 from trezorlib.btc import get_address, get_public_node
 from trezorlib.client import PASSPHRASE_TEST_PATH