diff --git a/trezor_agent/gpg/agent.py b/trezor_agent/gpg/agent.py
index cb32fef..47513ea 100644
--- a/trezor_agent/gpg/agent.py
+++ b/trezor_agent/gpg/agent.py
@@ -61,6 +61,7 @@ def _serialize_point(data):
 
 
 def parse_ecdh(line):
+    """Parse ECDH request and return remote public key."""
     prefix, line = line.split(' ', 1)
     assert prefix == 'D'
     exp, leftover = keyring.parse(keyring.unescape(line))
@@ -75,6 +76,7 @@ def parse_ecdh(line):
 
 
 def pkdecrypt(keygrip, conn):
+    """Handle decryption using ECDH."""
     for msg in [b'S INQUIRE_MAXLEN 4096', b'INQUIRE CIPHERTEXT']:
         keyring.sendline(conn, msg)
 
diff --git a/trezor_agent/gpg/encode.py b/trezor_agent/gpg/encode.py
index 41a91a1..7fcc8f1 100644
--- a/trezor_agent/gpg/encode.py
+++ b/trezor_agent/gpg/encode.py
@@ -41,6 +41,7 @@ class HardwareSigner(object):
         return (util.bytes2num(sig[:32]), util.bytes2num(sig[32:]))
 
     def ecdh(self, pubkey):
+        """Derive shared secret using ECDH from remote public key."""
         result = self.client_wrapper.connection.sign_identity(
             identity=self.identity,
             challenge_hidden=pubkey,
@@ -221,4 +222,5 @@ class Factory(object):
         return proto.packet(tag=2, blob=blob)
 
     def get_shared_secret(self, pubkey):
+        """Derive shared secret using ECDH from remote public key."""
         return self.conn.ecdh(pubkey)