diff --git a/libsignal-service/src/account_manager.rs b/libsignal-service/src/account_manager.rs
index fe3437bbd..47f715d3b 100644
--- a/libsignal-service/src/account_manager.rs
+++ b/libsignal-service/src/account_manager.rs
@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::convert::{TryFrom, TryInto};
 use std::time::SystemTime;
 
+use aes::cipher::generic_array::GenericArray;
 use aes::cipher::{KeyIvInit, StreamCipher as _};
 use hmac::{Hmac, Mac};
 use libsignal_protocol::{
@@ -583,10 +584,7 @@ pub fn encrypt_device_name<R: rand::Rng + rand::CryptoRng>(
 
     const IV: [u8; 16] = [0; 16];
     let mut cipher = Aes256Ctr128BE::new(
-        cipher_key
-            .as_slice()
-            .try_into()
-            .expect("fixed length key material"),
+        GenericArray::from_slice(cipher_key.as_slice()),
         &IV.into(),
     );
     cipher.apply_keystream(&mut ciphertext);
@@ -615,10 +613,7 @@ pub fn decrypt_device_name(
     let mut plaintext = ciphertext.to_vec();
     const IV: [u8; 16] = [0; 16];
     let mut cipher = Aes256Ctr128BE::new(
-        cipher_key
-            .as_slice()
-            .try_into()
-            .expect("fixed length key material"),
+        GenericArray::from_slice(cipher_key.as_slice()),
         &IV.into(),
     );
     cipher.apply_keystream(&mut plaintext);
@@ -678,8 +673,7 @@ mod tests {
         };
 
         let decrypted_device_name =
-            super::decrypt_device_name(&ephemeral_private_key, &device_name)
-                .unwrap();
+            super::decrypt_device_name(&ephemeral_private_key, &device_name)?;
 
         assert_eq!(decrypted_device_name, "Nokia 3310 Millenial Edition");
 
diff --git a/libsignal-service/src/attachment_cipher.rs b/libsignal-service/src/attachment_cipher.rs
index 83957d1c4..849a50a7f 100644
--- a/libsignal-service/src/attachment_cipher.rs
+++ b/libsignal-service/src/attachment_cipher.rs
@@ -1,6 +1,5 @@
-use std::convert::TryInto;
-
 use aes::cipher::block_padding::Pkcs7;
+use aes::cipher::generic_array::GenericArray;
 use aes::cipher::{BlockDecryptMut, BlockEncryptMut, KeyIvInit};
 use hmac::{Hmac, Mac};
 use sha2::Sha256;
@@ -35,10 +34,8 @@ pub fn encrypt_in_place(iv: [u8; 16], key: [u8; 64], plaintext: &mut Vec<u8>) {
     // Pad with zeroes for padding
     plaintext.extend(&[0u8; 16]);
 
-    let cipher = Aes256CbcEnc::new(
-        aes_half.try_into().expect("fixed length key material"),
-        &iv.into(),
-    );
+    let cipher =
+        Aes256CbcEnc::new(GenericArray::from_slice(aes_half), &iv.into());
 
     let buffer = plaintext;
     let ciphertext_slice = cipher
@@ -79,8 +76,8 @@ pub fn decrypt_in_place(
     let (iv, buffer) = buffer.split_at_mut(16);
 
     let cipher = Aes256CbcDec::new(
-        aes_half.try_into().expect("fixed length key material"),
-        (&*iv).try_into().expect("fixed length iv material"),
+        GenericArray::from_slice(aes_half),
+        GenericArray::from_slice(iv),
     );
 
     let plaintext_slice = cipher
diff --git a/libsignal-service/src/envelope.rs b/libsignal-service/src/envelope.rs
index 1b014010b..5f5bd0a8c 100644
--- a/libsignal-service/src/envelope.rs
+++ b/libsignal-service/src/envelope.rs
@@ -1,6 +1,7 @@
 use std::convert::{TryFrom, TryInto};
 
 use aes::cipher::block_padding::Pkcs7;
+use aes::cipher::generic_array::GenericArray;
 use aes::cipher::{BlockDecryptMut, KeyIvInit};
 use prost::Message;
 use uuid::Uuid;
@@ -71,8 +72,8 @@ impl Envelope {
             // but that should not matter.
             // https://crypto.stackexchange.com/questions/9043/what-is-the-difference-between-pkcs5-padding-and-pkcs7-padding
             let cipher = cbc::Decryptor::<aes::Aes256>::new(
-                aes_key.try_into().expect("fixed length key material"),
-                iv.try_into().expect("fixed length iv material"),
+                GenericArray::from_slice(aes_key),
+                GenericArray::from_slice(iv),
             );
             let input = &input[CIPHERTEXT_OFFSET..(input.len() - MAC_SIZE)];
             let input = cipher