diff --git a/src/identity/mixnet.rs b/src/identity/mixnet.rs
index 3783dffd97..10e081a4fa 100644
--- a/src/identity/mixnet.rs
+++ b/src/identity/mixnet.rs
@@ -23,11 +23,11 @@ impl KeyPair {
         KeyPair { private, public }
     }
 
-    pub fn private_bytes(&self) -> Vec<u8> {
-        self.private.to_bytes().to_vec()
+    pub fn private_bytes(&self) -> [u8; 32] {
+        self.private.to_bytes()
     }
 
-    pub fn public_bytes(&self) -> Vec<u8> {
-        self.public.to_bytes().to_vec()
+    pub fn public_bytes(&self) -> [u8; 32] {
+        self.public.to_bytes()
     }
 }
diff --git a/src/persistence/pemstore.rs b/src/persistence/pemstore.rs
index c935fab437..02c1f5db00 100644
--- a/src/persistence/pemstore.rs
+++ b/src/persistence/pemstore.rs
@@ -52,10 +52,10 @@ impl PemStore {
         );
     }
 
-    fn write_pem_file(&self, filepath: PathBuf, data: Vec<u8>, tag: String) {
+    fn write_pem_file(&self, filepath: PathBuf, data: [u8; 32], tag: String) {
         let pem = Pem {
             tag,
-            contents: data,
+            contents: data.to_vec(),
         };
         let key = encode(&pem);