diff --git a/Cargo.lock b/Cargo.lock
index 648d584..fbeb2af 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "aead"
 version = "0.3.2"
@@ -556,7 +558,7 @@ checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 
 [[package]]
 name = "opaque-ke"
-version = "0.5.0"
+version = "0.5.1-pre.1"
 dependencies = [
  "anyhow",
  "base64",
diff --git a/Cargo.toml b/Cargo.toml
index a8c3597..ac6248e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "opaque-ke"
-version = "0.5.0"
+version = "0.5.1-pre.1"
 repository = "https://github.com/novifinancial/opaque-ke"
 keywords = ["cryptography", "crypto", "opaque", "passwords", "authentication"]
 description = "An implementation of the OPAQUE password-authenticated key exchange protocol"
diff --git a/src/envelope.rs b/src/envelope.rs
index a10a4f5..50a909b 100644
--- a/src/envelope.rs
+++ b/src/envelope.rs
@@ -16,6 +16,7 @@ use hkdf::Hkdf;
 use hmac::{Hmac, Mac, NewMac};
 use rand::{CryptoRng, RngCore};
 use std::convert::TryFrom;
+use zeroize::Zeroize;
 
 // Constant string used as salt for HKDF computation
 const STR_PAD: &[u8] = b"Pad";
@@ -24,7 +25,8 @@ const STR_EXPORT_KEY: &[u8] = b"ExportKey";
 
 const NONCE_LEN: usize = 32;
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, PartialEq, Zeroize)]
+#[zeroize(drop)]
 pub(crate) enum InnerEnvelopeMode {
     Base = 1,
     CustomIdentifier = 2,
@@ -41,6 +43,8 @@ impl TryFrom<u8> for InnerEnvelopeMode {
     }
 }
 
+#[derive(Clone, Zeroize)]
+#[zeroize(drop)]
 pub(crate) struct InnerEnvelope {
     mode: InnerEnvelopeMode,
     nonce: Vec<u8>,
@@ -78,6 +82,15 @@ impl InnerEnvelope {
             bytes[NONCE_LEN + key_len..].to_vec(),
         ))
     }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        vec![
+            /* Cannot easily get raw pointer of enum value, otherwise would do self.mode.as_ptr() */
+            (self.nonce.as_ptr(), self.nonce.len()),
+            (self.ciphertext.as_ptr(), self.ciphertext.len()),
+        ]
+    }
 }
 
 /// This struct is an instantiation of the envelope as described in
@@ -90,6 +103,7 @@ impl InnerEnvelope {
 /// The specification update has simplified this assumption by taking
 /// an XOR-based approach without compromising on security, and to avoid
 /// the confusion around the implementation of an RKR-secure encryption.
+#[derive(Clone)]
 pub(crate) struct Envelope<D: Hash> {
     inner_envelope: InnerEnvelope,
     hmac: GenericArray<u8, <D as Digest>::OutputSize>,
@@ -284,6 +298,29 @@ impl<D: Hash> Envelope<D> {
             ),
         })
     }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        [
+            self.inner_envelope.as_byte_ptrs(),
+            vec![(self.hmac.as_ptr(), self.hmac.len())],
+        ]
+        .concat()
+    }
+}
+
+// This can't be derived because of the use of a phantom parameter
+impl<D: Hash> Zeroize for Envelope<D> {
+    fn zeroize(&mut self) {
+        self.inner_envelope.zeroize();
+        self.hmac.zeroize();
+    }
+}
+
+impl<D: Hash> Drop for Envelope<D> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
 }
 
 // Helper functions
diff --git a/src/key_exchange/traits.rs b/src/key_exchange/traits.rs
index c88ad01..e1df71a 100644
--- a/src/key_exchange/traits.rs
+++ b/src/key_exchange/traits.rs
@@ -12,10 +12,11 @@ use crate::{
 use rand::{CryptoRng, RngCore};
 
 use std::convert::TryFrom;
+use zeroize::Zeroize;
 
 pub trait KeyExchange<D: Hash, G: Group> {
-    type KE1State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
-    type KE2State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
+    type KE1State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytesWithPointers + Zeroize;
+    type KE2State: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytesWithPointers + Zeroize;
     type KE1Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
     type KE2Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
     type KE3Message: for<'r> TryFrom<&'r [u8], Error = PakeError> + ToBytes;
@@ -62,3 +63,11 @@ pub trait KeyExchange<D: Hash, G: Group> {
 pub trait ToBytes {
     fn to_bytes(&self) -> Vec<u8>;
 }
+
+pub trait ToBytesWithPointers {
+    fn to_bytes(&self) -> Vec<u8>;
+
+    // Only used for tests to grab raw pointers to data
+    #[cfg(test)]
+    fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)>;
+}
diff --git a/src/key_exchange/tripledh.rs b/src/key_exchange/tripledh.rs
index 708158a..2c504f5 100644
--- a/src/key_exchange/tripledh.rs
+++ b/src/key_exchange/tripledh.rs
@@ -11,7 +11,7 @@ use crate::{
     },
     group::Group,
     hash::Hash,
-    key_exchange::traits::{KeyExchange, ToBytes},
+    key_exchange::traits::{KeyExchange, ToBytes, ToBytesWithPointers},
     keypair::{Key, KeyPair, SizedBytesExt},
     serialization::{serialize, tokenize},
 };
@@ -24,6 +24,7 @@ use generic_bytes::SizedBytes;
 use hkdf::Hkdf;
 use hmac::{Hmac, Mac, NewMac};
 use rand::{CryptoRng, RngCore};
+use zeroize::Zeroize;
 
 use std::convert::TryFrom;
 
@@ -237,7 +238,8 @@ impl<D: Hash, G: Group> KeyExchange<D, G> for TripleDH {
 }
 
 /// The client state produced after the first key exchange message
-#[derive(PartialEq, Eq)]
+#[derive(PartialEq, Eq, Zeroize)]
+#[zeroize(drop)]
 pub struct Ke1State {
     client_e_sk: Key,
     client_nonce: GenericArray<u8, NonceLen>,
@@ -267,11 +269,22 @@ impl TryFrom<&[u8]> for Ke1State {
     }
 }
 
-impl ToBytes for Ke1State {
+impl ToBytesWithPointers for Ke1State {
     fn to_bytes(&self) -> Vec<u8> {
         let output: Vec<u8> = [&self.client_e_sk.to_arr(), &self.client_nonce[..]].concat();
         output
     }
+
+    #[cfg(test)]
+    fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        vec![
+            (
+                self.client_e_sk.as_ptr(),
+                <Key as SizedBytes>::Len::to_usize(),
+            ),
+            (self.client_nonce.as_ptr(), NonceLen::to_usize()),
+        ]
+    }
 }
 
 impl ToBytes for Ke1Message {
@@ -311,15 +324,22 @@ pub struct Ke2State<HashLen: ArrayLength<u8>> {
     session_key: GenericArray<u8, HashLen>,
 }
 
-/// The second key exchange message
-pub struct Ke2Message<HashLen: ArrayLength<u8>> {
-    server_nonce: GenericArray<u8, NonceLen>,
-    server_e_pk: Key,
-    e_info: Vec<u8>,
-    mac: GenericArray<u8, HashLen>,
+// This can't be derived because of the use of a phantom parameter
+impl<HashLen: ArrayLength<u8>> Zeroize for Ke2State<HashLen> {
+    fn zeroize(&mut self) {
+        self.km3.zeroize();
+        self.hashed_transcript.zeroize();
+        self.session_key.zeroize();
+    }
 }
 
-impl<HashLen: ArrayLength<u8>> ToBytes for Ke2State<HashLen> {
+impl<HashLen: ArrayLength<u8>> Drop for Ke2State<HashLen> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
+impl<HashLen: ArrayLength<u8>> ToBytesWithPointers for Ke2State<HashLen> {
     fn to_bytes(&self) -> Vec<u8> {
         [
             &self.km3[..],
@@ -328,6 +348,23 @@ impl<HashLen: ArrayLength<u8>> ToBytes for Ke2State<HashLen> {
         ]
         .concat()
     }
+
+    #[cfg(test)]
+    fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        vec![
+            (self.km3.as_ptr(), HashLen::to_usize()),
+            (self.hashed_transcript.as_ptr(), HashLen::to_usize()),
+            (self.session_key.as_ptr(), HashLen::to_usize()),
+        ]
+    }
+}
+
+/// The second key exchange message
+pub struct Ke2Message<HashLen: ArrayLength<u8>> {
+    server_nonce: GenericArray<u8, NonceLen>,
+    server_e_pk: Key,
+    e_info: Vec<u8>,
+    mac: GenericArray<u8, HashLen>,
 }
 
 impl<HashLen: ArrayLength<u8>> TryFrom<&[u8]> for Ke2State<HashLen> {
diff --git a/src/keypair.rs b/src/keypair.rs
index edae451..27f85f1 100644
--- a/src/keypair.rs
+++ b/src/keypair.rs
@@ -5,8 +5,12 @@
 
 //! Contains the keypair types that must be supplied for the OPAQUE API
 
+#![allow(unsafe_code)]
+
 use crate::errors::InternalPakeError;
 use crate::group::Group;
+#[cfg(test)]
+use generic_array::typenum::Unsigned;
 use generic_array::{typenum::U32, GenericArray};
 use generic_bytes::{SizedBytes, TryFromSizedBytesError};
 #[cfg(test)]
@@ -31,13 +35,27 @@ pub trait SizedBytesExt: SizedBytes {
 impl<T> SizedBytesExt for T where T: SizedBytes {}
 
 /// A Keypair trait with public-private verification
-#[derive(Clone, Debug, PartialEq, Eq, Zeroize)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct KeyPair<G> {
     pk: Key,
     sk: Key,
     _g: PhantomData<G>,
 }
 
+// This can't be derived because of the use of a phantom parameter
+impl<G> Zeroize for KeyPair<G> {
+    fn zeroize(&mut self) {
+        self.pk.zeroize();
+        self.sk.zeroize();
+    }
+}
+
+impl<G> Drop for KeyPair<G> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
 impl<G: Group> KeyPair<G> {
     /// The public key component
     pub fn public(&self) -> &Key {
@@ -100,6 +118,14 @@ impl<G: Group> KeyPair<G> {
         let pk = Self::public_from_private(&sk);
         Self::new(pk, sk)
     }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        vec![
+            (self.pk.as_ptr(), <Key as SizedBytes>::Len::to_usize()),
+            (self.sk.as_ptr(), <Key as SizedBytes>::Len::to_usize()),
+        ]
+    }
 }
 
 #[cfg(test)]
@@ -149,7 +175,41 @@ impl SizedBytes for Key {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::errors::*;
     use curve25519_dalek::ristretto::RistrettoPoint;
+    use generic_array::typenum::Unsigned;
+    use rand::rngs::OsRng;
+    use std::slice::from_raw_parts;
+
+    #[test]
+    fn test_zeroize_key() -> Result<(), ProtocolError> {
+        let key_len = <Key as SizedBytes>::Len::to_usize();
+        let mut key = Key(vec![1u8; key_len]);
+        let ptr = key.as_ptr();
+
+        key.zeroize();
+
+        let bytes = unsafe { from_raw_parts(ptr, key_len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_zeroize_keypair() -> Result<(), ProtocolError> {
+        let mut rng = OsRng;
+        let mut keypair = KeyPair::<RistrettoPoint>::generate_random(&mut rng);
+        let ptrs = keypair.as_byte_ptrs();
+
+        keypair.zeroize();
+
+        for (ptr, len) in ptrs {
+            let bytes = unsafe { from_raw_parts(ptr, len) };
+            assert!(bytes.iter().all(|&x| x == 0));
+        }
+
+        Ok(())
+    }
 
     proptest! {
         #[test]
diff --git a/src/opaque.rs b/src/opaque.rs
index e867ef1..35c6f6d 100644
--- a/src/opaque.rs
+++ b/src/opaque.rs
@@ -11,7 +11,7 @@ use crate::{
     errors::{utils::check_slice_size_atleast, InternalPakeError, PakeError, ProtocolError},
     group::Group,
     hash::Hash,
-    key_exchange::traits::{KeyExchange, ToBytes},
+    key_exchange::traits::{KeyExchange, ToBytesWithPointers},
     keypair::{Key, KeyPair, SizedBytesExt},
     map_to_curve::GroupWithMapToCurve,
     oprf,
@@ -73,6 +73,14 @@ impl<CS: CipherSuite> ClientRegistration<CS> {
             },
         })
     }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        vec![
+            (self.token.data.as_ptr(), self.token.data.len()),
+            /* cannot provide raw pointer to self.token.blind until this is exposed in curve25519_dalek::scalar::Scalar */
+        ]
+    }
 }
 
 /// Optional parameters for client registration finish
@@ -140,6 +148,9 @@ pub struct ClientRegistrationFinishResult<CS: CipherSuite> {
     pub message: RegistrationUpload<CS>,
     /// The export key output by client registration
     pub export_key: GenericArray<u8, <CS::Hash as Digest>::OutputSize>,
+    /// Instance of the ClientRegistration, only used in tests for checking zeroize
+    #[cfg(test)]
+    pub state: ClientRegistration<CS>,
 }
 
 impl<CS: CipherSuite> ClientRegistration<CS> {
@@ -203,38 +214,12 @@ impl<CS: CipherSuite> ClientRegistration<CS> {
                 client_s_pk: client_static_keypair.public().clone(),
             },
             export_key,
+            #[cfg(test)]
+            state: self,
         })
     }
 }
 
-// This can't be derived because of the use of a phantom parameter
-impl<CS: CipherSuite> Zeroize for ClientRegistration<CS> {
-    fn zeroize(&mut self) {
-        self.token.data.zeroize();
-        self.token.blind.zeroize();
-    }
-}
-
-impl<CS: CipherSuite> Drop for ClientRegistration<CS> {
-    fn drop(&mut self) {
-        self.zeroize();
-    }
-}
-
-// This can't be derived because of the use of a phantom parameter
-impl<CS: CipherSuite> Zeroize for ClientLogin<CS> {
-    fn zeroize(&mut self) {
-        self.token.data.zeroize();
-        self.token.blind.zeroize();
-    }
-}
-
-impl<CS: CipherSuite> Drop for ClientLogin<CS> {
-    fn drop(&mut self) {
-        self.zeroize();
-    }
-}
-
 /// Contains the fields that are returned by a server registration start
 pub struct ServerRegistrationStartResult<CS: CipherSuite> {
     /// The registration resposne message to send to the client
@@ -295,6 +280,21 @@ impl<CS: CipherSuite> ServerRegistration<CS> {
         })
     }
 
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        [
+            match &self.envelope {
+                Some(env) => env.as_byte_ptrs(),
+                None => vec![],
+            },
+            match &self.client_s_pk {
+                Some(pk) => vec![(pk.as_ptr(), pk.len())],
+                None => vec![],
+            },
+            /* cannot provide raw pointer to self.oprf_key until this is exposed in curve25519_dalek::scalar::Scalar */
+        ].concat()
+    }
+
     /// From the client's "blinded" password, returns a response to be
     /// sent back to the client, as well as a ServerRegistration
     ///
@@ -380,7 +380,7 @@ impl<CS: CipherSuite> ServerRegistration<CS> {
         Ok(Self {
             envelope: Some(message.envelope),
             client_s_pk: Some(message.client_s_pk),
-            oprf_key: self.oprf_key,
+            oprf_key: self.oprf_key.clone(),
         })
     }
 }
@@ -440,6 +440,18 @@ impl<CS: CipherSuite> ClientLogin<CS> {
             serialized_credential_request,
         })
     }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        [
+            vec![
+                (self.token.data.as_ptr(), self.token.data.len()),
+                /* cannot provide raw pointer to self.token.blind until this is exposed in curve25519_dalek::scalar::Scalar */
+            ],
+            self.ke1_state.as_byte_ptrs(),
+            vec![ (self.serialized_credential_request.as_ptr(), self.serialized_credential_request.len()) ],
+        ].concat()
+    }
 }
 
 /// Optional parameters for client login start
@@ -488,6 +500,9 @@ pub struct ClientLoginFinishResult<CS: CipherSuite> {
     pub server_s_pk: Key,
     /// The confidential info sent by the client
     pub confidential_info: Vec<u8>,
+    /// Instance of the ClientLogin, only used in tests for checking zeroize
+    #[cfg(test)]
+    pub state: ClientLogin<CS>,
 }
 
 impl<CS: CipherSuite> ClientLogin<CS> {
@@ -626,6 +641,8 @@ impl<CS: CipherSuite> ClientLogin<CS> {
             session_key,
             export_key: opened_envelope.export_key.clone(),
             server_s_pk: l2.server_s_pk,
+            #[cfg(test)]
+            state: self,
         })
     }
 }
@@ -665,9 +682,13 @@ pub struct ServerLoginStartResult<CS: CipherSuite> {
 }
 
 /// Contains the fields that are returned by a server login finish
-pub struct ServerLoginFinishResult {
+pub struct ServerLoginFinishResult<CS: CipherSuite> {
     /// The session key between client and server
     pub session_key: Vec<u8>,
+    _cs: PhantomData<CS>,
+    /// Instance of the ClientRegistration, only used in tests for checking zeroize
+    #[cfg(test)]
+    pub state: ServerLogin<CS>,
 }
 
 impl<CS: CipherSuite> ServerLogin<CS> {
@@ -728,6 +749,7 @@ impl<CS: CipherSuite> ServerLogin<CS> {
     ) -> Result<ServerLoginStartResult<CS>, ProtocolError> {
         let client_s_pk = password_file
             .client_s_pk
+            .clone()
             .ok_or(InternalPakeError::SealError)?;
 
         let (e_info, optional_ids) = match params {
@@ -740,7 +762,10 @@ impl<CS: CipherSuite> ServerLogin<CS> {
             }
         };
 
-        let envelope = password_file.envelope.ok_or(InternalPakeError::SealError)?;
+        let envelope = password_file
+            .envelope
+            .clone()
+            .ok_or(InternalPakeError::SealError)?;
         if envelope.get_mode() != mode_from_ids(&optional_ids) {
             return Err(InternalPakeError::IncompatibleEnvelopeModeError.into());
         }
@@ -827,9 +852,9 @@ impl<CS: CipherSuite> ServerLogin<CS> {
     /// # Ok::<(), ProtocolError>(())
     /// ```
     pub fn finish(
-        &self,
+        self,
         message: CredentialFinalization<CS>,
-    ) -> Result<ServerLoginFinishResult, ProtocolError> {
+    ) -> Result<ServerLoginFinishResult<CS>, ProtocolError> {
         let session_key = <CS::KeyExchange as KeyExchange<CS::Hash, CS::Group>>::finish_ke(
             message.ke3_message,
             &self.ke2_state,
@@ -841,11 +866,82 @@ impl<CS: CipherSuite> ServerLogin<CS> {
             err => err,
         })?;
 
-        Ok(ServerLoginFinishResult { session_key })
+        Ok(ServerLoginFinishResult {
+            session_key,
+            _cs: PhantomData,
+            #[cfg(test)]
+            state: self,
+        })
+    }
+
+    #[cfg(test)]
+    pub fn as_byte_ptrs(&self) -> Vec<(*const u8, usize)> {
+        self.ke2_state.as_byte_ptrs()
+    }
+}
+
+// Zeroize on drop implementations
+
+// This can't be derived because of the use of a phantom parameter
+impl<CS: CipherSuite> Zeroize for ClientRegistration<CS> {
+    fn zeroize(&mut self) {
+        self.token.data.zeroize();
+        self.token.blind.zeroize();
+    }
+}
+
+impl<CS: CipherSuite> Drop for ClientRegistration<CS> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
+// This can't be derived because of the use of a phantom parameter
+impl<CS: CipherSuite> Zeroize for ServerRegistration<CS> {
+    fn zeroize(&mut self) {
+        self.envelope.zeroize();
+        self.client_s_pk.zeroize();
+        self.oprf_key.zeroize();
+    }
+}
+
+impl<CS: CipherSuite> Drop for ServerRegistration<CS> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
+// This can't be derived because of the use of a phantom parameter
+impl<CS: CipherSuite> Zeroize for ClientLogin<CS> {
+    fn zeroize(&mut self) {
+        self.token.data.zeroize();
+        self.token.blind.zeroize();
+        self.ke1_state.zeroize();
+        self.serialized_credential_request.zeroize();
+    }
+}
+
+impl<CS: CipherSuite> Drop for ClientLogin<CS> {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
+// This can't be derived because of the use of a phantom parameter
+impl<CS: CipherSuite> Zeroize for ServerLogin<CS> {
+    fn zeroize(&mut self) {
+        self.ke2_state.zeroize();
+    }
+}
+
+impl<CS: CipherSuite> Drop for ServerLogin<CS> {
+    fn drop(&mut self) {
+        self.zeroize();
     }
 }
 
 // Helper functions
+
 fn get_password_derived_key<G: GroupWithMapToCurve, SH: SlowHash<D>, D: Hash>(
     token: &oprf::Token<G>,
     beta: G,
diff --git a/src/tests/full_test.rs b/src/tests/full_test.rs
index e68b814..85fc6f3 100644
--- a/src/tests/full_test.rs
+++ b/src/tests/full_test.rs
@@ -3,6 +3,8 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
+#![allow(unsafe_code)]
+
 use crate::{
     ciphersuite::CipherSuite,
     errors::*,
@@ -19,6 +21,8 @@ use generic_array::typenum::Unsigned;
 use generic_bytes::SizedBytes;
 use rand::{rngs::OsRng, RngCore};
 use serde_json::Value;
+use std::slice::from_raw_parts;
+use zeroize::Zeroize;
 
 // Tests
 // =====
@@ -65,6 +69,8 @@ pub struct TestVectorParameters {
     pub session_key: Vec<u8>,
 }
 
+static STR_PASSWORD: &str = "password";
+
 static TEST_VECTOR: &str = r#"
 {
     "client_s_pk": "6e0a6082dd29936c44b47ecb8a5fe72e4b321a0ac314b0080ca4c48afdabd215",
@@ -416,7 +422,7 @@ fn generate_parameters<CS: CipherSuite>() -> TestVectorParameters {
         server_registration_state,
         client_login_state,
         server_login_state,
-        session_key: client_login_finish_result.session_key,
+        session_key: client_login_finish_result.session_key.clone(),
         export_key: client_registration_finish_result.export_key.to_vec(),
     }
 }
@@ -623,7 +629,7 @@ fn test_server_login_finish() -> Result<(), ProtocolError> {
 
     assert_eq!(
         hex::encode(parameters.session_key),
-        hex::encode(server_login_result.session_key)
+        hex::encode(&server_login_result.session_key)
     );
 
     Ok(())
@@ -680,8 +686,8 @@ fn test_complete_flow(
             .finish(client_login_finish_result.message)?;
 
         assert_eq!(
-            hex::encode(server_login_finish_result.session_key),
-            hex::encode(client_login_finish_result.session_key)
+            hex::encode(&server_login_finish_result.session_key),
+            hex::encode(&client_login_finish_result.session_key)
         );
         assert_eq!(
             hex::encode(client_registration_finish_result.export_key),
@@ -706,3 +712,305 @@ fn test_complete_flow_success() -> Result<(), ProtocolError> {
 fn test_complete_flow_fail() -> Result<(), ProtocolError> {
     test_complete_flow(b"good password", b"bad password")
 }
+
+// Zeroize tests
+
+#[test]
+fn test_zeroize_client_registration_start() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+
+    let mut state = client_registration_start_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_server_registration_start() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+
+    let mut state = server_registration_start_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_client_registration_finish() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+
+    let mut state = client_registration_finish_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_server_registration_finish() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+    let p_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)?;
+
+    let mut state = p_file;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_client_login_start() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_rng,
+        STR_PASSWORD.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )?;
+
+    let mut state = client_login_start_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_server_login_start() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+    let p_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)?;
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_rng,
+        STR_PASSWORD.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )?;
+    let server_login_start_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut server_rng,
+        p_file,
+        &server_kp.private(),
+        client_login_start_result.message,
+        ServerLoginStartParameters::default(),
+    )?;
+
+    let mut state = server_login_start_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_client_login_finish() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+    let p_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)?;
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_rng,
+        STR_PASSWORD.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )?;
+    let server_login_start_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut server_rng,
+        p_file,
+        &server_kp.private(),
+        client_login_start_result.message,
+        ServerLoginStartParameters::default(),
+    )?;
+    let client_login_finish_result = client_login_start_result.state.finish(
+        server_login_start_result.message,
+        ClientLoginFinishParameters::default(),
+    )?;
+
+    let mut state = client_login_finish_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
+
+#[test]
+fn test_zeroize_server_login_finish() -> Result<(), ProtocolError> {
+    let mut client_rng = OsRng;
+    let mut server_rng = OsRng;
+    let server_kp = RistrettoSha5123dhNoSlowHash::generate_random_keypair(&mut server_rng);
+    let client_registration_start_result =
+        ClientRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut client_rng,
+            STR_PASSWORD.as_bytes(),
+        )?;
+    let server_registration_start_result =
+        ServerRegistration::<RistrettoSha5123dhNoSlowHash>::start(
+            &mut server_rng,
+            client_registration_start_result.message,
+            server_kp.public(),
+        )?;
+    let client_registration_finish_result = client_registration_start_result.state.finish(
+        &mut client_rng,
+        server_registration_start_result.message,
+        ClientRegistrationFinishParameters::default(),
+    )?;
+    let p_file = server_registration_start_result
+        .state
+        .finish(client_registration_finish_result.message)?;
+    let client_login_start_result = ClientLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut client_rng,
+        STR_PASSWORD.as_bytes(),
+        ClientLoginStartParameters::default(),
+    )?;
+    let server_login_start_result = ServerLogin::<RistrettoSha5123dhNoSlowHash>::start(
+        &mut server_rng,
+        p_file,
+        &server_kp.private(),
+        client_login_start_result.message,
+        ServerLoginStartParameters::default(),
+    )?;
+    let client_login_finish_result = client_login_start_result.state.finish(
+        server_login_start_result.message,
+        ClientLoginFinishParameters::default(),
+    )?;
+    let server_login_finish_result = server_login_start_result
+        .state
+        .finish(client_login_finish_result.message)?;
+
+    let mut state = server_login_finish_result.state;
+    let ptrs = state.as_byte_ptrs();
+    state.zeroize();
+
+    for (ptr, len) in ptrs {
+        let bytes = unsafe { from_raw_parts(ptr, len) };
+        assert!(bytes.iter().all(|&x| x == 0));
+    }
+
+    Ok(())
+}
diff --git a/src/tests/opaque_test_vectors.rs b/src/tests/opaque_test_vectors.rs
index 2c0c3aa..0e9d0a3 100644
--- a/src/tests/opaque_test_vectors.rs
+++ b/src/tests/opaque_test_vectors.rs
@@ -576,7 +576,7 @@ fn test_server_login_finish() -> Result<(), ProtocolError> {
 
         assert_eq!(
             hex::encode(parameters.session_key),
-            hex::encode(server_login_result.session_key)
+            hex::encode(&server_login_result.session_key)
         );
     }
     Ok(())