diff --git a/src/allmydata/crypto/aes.py b/src/allmydata/crypto/aes.py
index e921e8e15..42470e14d 100644
--- a/src/allmydata/crypto/aes.py
+++ b/src/allmydata/crypto/aes.py
@@ -1,4 +1,3 @@
-import os
 import six
 
 from cryptography.hazmat.backends import default_backend
diff --git a/src/allmydata/crypto/rsa.py b/src/allmydata/crypto/rsa.py
index f3d1f999a..024831f97 100644
--- a/src/allmydata/crypto/rsa.py
+++ b/src/allmydata/crypto/rsa.py
@@ -19,19 +19,6 @@ signatures to fail to validate.
 RSA_PSS_SALT_LENGTH = 32
 
 
-def create_verifying_key_from_string(public_key_der):
-    """
-    Create an RSA verifying key from a previously serialized public key.
-
-    :returns: public key
-    """
-    pub_key = load_der_public_key(
-        public_key_der,
-        backend=default_backend(),
-    )
-    return pub_key
-
-
 def create_signing_keypair(key_size):
     """
     Create a new RSA signing keypair from scratch. Can be used with
@@ -88,7 +75,7 @@ def der_string_from_verifying_key(public_key):
 
 def create_verifying_key_from_string(public_key_der):
     """
-    Create an RSA signing key from a previously serialized public key
+    Create an RSA verifying key from a previously serialized public key
     """
     pub_key = load_der_public_key(
         public_key_der,
diff --git a/src/allmydata/test/test_introducer.py b/src/allmydata/test/test_introducer.py
index 44ef2d775..540492f5d 100644
--- a/src/allmydata/test/test_introducer.py
+++ b/src/allmydata/test/test_introducer.py
@@ -15,7 +15,6 @@ from twisted.python.filepath import FilePath
 from foolscap.api import Tub, Referenceable, fireEventually, flushEventualQueue
 from twisted.application import service
 from allmydata import crypto
-from allmydata.crypto import ed25519
 from allmydata.crypto.ed25519 import SigningKey
 from allmydata.interfaces import InsufficientVersionError
 from allmydata.introducer.client import IntroducerClient