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// Copyright 2022 The Matrix.org Foundation C.I.C.
// Copyright 2021 Damir Jelić
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#![doc = include_str!("../README.md")]
#![warn(missing_debug_implementations, missing_docs)]
use std::ops::DerefMut;
use base64::{
alphabet,
engine::{general_purpose, GeneralPurpose},
Engine,
};
use blake3::{derive_key, Hash};
use chacha20poly1305::{
aead::{Aead, Error as EncryptionError},
Key as ChachaKey, KeyInit, XChaCha20Poly1305, XNonce,
};
use hmac::Hmac;
use pbkdf2::pbkdf2;
use rand::{thread_rng, Error as RandomError, Fill};
use serde::{de::DeserializeOwned, Deserialize, Serialize};
use sha2::Sha256;
use zeroize::{Zeroize, ZeroizeOnDrop};
const VERSION: u8 = 1;
const KDF_SALT_SIZE: usize = 32;
const XNONCE_SIZE: usize = 24;
const KDF_ROUNDS: u32 = 200_000;
const BASE64: GeneralPurpose = GeneralPurpose::new(&alphabet::STANDARD, general_purpose::NO_PAD);
type MacKeySeed = [u8; 32];
/// Error type for the `StoreCipher` operations.
#[derive(Debug, thiserror::Error)]
pub enum Error {
/// Failed to serialize a value.
#[error("Failed to serialize a value: `{0}`")]
Serialization(#[from] rmp_serde::encode::Error),
/// Failed to deserialize a value.
#[error("Failed to deserialize a value: `{0}`")]
Deserialization(#[from] rmp_serde::decode::Error),
/// Failed to deserialize or serialize a JSON value.
#[error("Failed to deserialize or serialize a JSON value: `{0}`")]
Json(#[from] serde_json::Error),
/// Error encrypting or decrypting a value.
#[error("Error encrypting or decrypting a value: `{0}`")]
Encryption(#[from] EncryptionError),
/// Could not generate enough randomness for a cryptographic operation: {0}
#[error("Could not generate enough randomness for a cryptographic operation: `{0}`")]
Random(#[from] RandomError),
/// Unsupported ciphertext version.
#[error("Unsupported ciphertext version, expected `{0}`, got `{1}`")]
Version(u8, u8),
/// The ciphertext had an invalid length.
#[error("The ciphertext had an invalid length, expected `{0}`, got `{1}`")]
Length(usize, usize),
/// Failed to import a store cipher, the export used a passphrase while
/// we are trying to import it using a key or vice-versa.
#[error("Failed to import a store cipher, the export used a passphrase while we are trying to import it using a key or vice-versa")]
KdfMismatch,
}
/// An encryption key that can be used to encrypt data for key/value stores.
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// // Export the store cipher and persist it in your key/value store
/// let export = store_cipher.export("secret-passphrase")?;
///
/// let value = json!({
/// "some": "data",
/// });
///
/// let encrypted = store_cipher.encrypt_value(&value)?;
/// let decrypted: Value = store_cipher.decrypt_value(&encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
#[allow(missing_debug_implementations)]
pub struct StoreCipher {
inner: Keys,
}
impl StoreCipher {
/// Generate a new random store cipher.
pub fn new() -> Result<Self, Error> {
Ok(Self { inner: Keys::new()? })
}
/// Encrypt the store cipher using the given passphrase and export it.
///
/// This method can be used to persist the `StoreCipher` in an unencrypted
/// key/value store in a safe manner.
///
/// The `StoreCipher` can later on be restored using
/// [`StoreCipher::import`].
///
/// # Arguments
///
/// * `passphrase` - The passphrase that should be used to encrypt the store
/// cipher.
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::json;
///
/// let store_cipher = StoreCipher::new()?;
///
/// // Export the store cipher and persist it in your key/value store
/// let export = store_cipher.export("secret-passphrase");
///
/// // Save the export in your key/value store.
/// # anyhow::Ok(()) };
/// ```
pub fn export(&self, passphrase: &str) -> Result<Vec<u8>, Error> {
self.export_kdf(passphrase, KDF_ROUNDS)
}
/// Encrypt the store cipher using the given key and export it.
///
/// This method can be used to persist the `StoreCipher` in an unencrypted
/// key/value store in a safe manner.
///
/// The `StoreCipher` can later on be restored using
/// [`StoreCipher::import_with_key`].
///
/// # Arguments
///
/// * `key` - The 32-byte key to be used to encrypt the store cipher. It's
/// recommended to use a freshly and securely generated random key.
///
/// # Examples
///
/// ```rust,no_run
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::json;
///
/// let store_cipher = StoreCipher::new()?;
///
/// // Export the store cipher and persist it in your key/value store
/// let export = store_cipher.export_with_key(&[0u8; 32]);
///
/// // Save the export in your key/value store.
/// # anyhow::Ok(()) };
/// ```
pub fn export_with_key(&self, key: &[u8; 32]) -> Result<Vec<u8>, Error> {
let store_cipher = self.export_helper(key, KdfInfo::None)?;
Ok(rmp_serde::to_vec_named(&store_cipher).expect("Can't serialize the store cipher"))
}
fn export_helper(
&self,
key: &[u8; 32],
kdf_info: KdfInfo,
) -> Result<EncryptedStoreCipher, Error> {
let key = ChachaKey::from_slice(key.as_ref());
let cipher = XChaCha20Poly1305::new(key);
let nonce = Keys::get_nonce()?;
let mut keys = [0u8; 64];
keys[0..32].copy_from_slice(self.inner.encryption_key.as_ref());
keys[32..64].copy_from_slice(self.inner.mac_key_seed.as_ref());
let ciphertext = cipher.encrypt(XNonce::from_slice(&nonce), keys.as_ref())?;
keys.zeroize();
Ok(EncryptedStoreCipher {
kdf_info,
ciphertext_info: CipherTextInfo::ChaCha20Poly1305 { nonce, ciphertext },
})
}
#[doc(hidden)]
pub fn _insecure_export_fast_for_testing(&self, passphrase: &str) -> Result<Vec<u8>, Error> {
self.export_kdf(passphrase, 1000)
}
fn export_kdf(&self, passphrase: &str, kdf_rounds: u32) -> Result<Vec<u8>, Error> {
let mut rng = thread_rng();
let mut salt = [0u8; KDF_SALT_SIZE];
salt.try_fill(&mut rng)?;
let key = StoreCipher::expand_key(passphrase, &salt, kdf_rounds);
let store_cipher = self.export_helper(
&key,
KdfInfo::Pbkdf2ToChaCha20Poly1305 { rounds: kdf_rounds, kdf_salt: salt },
)?;
Ok(rmp_serde::to_vec_named(&store_cipher).expect("Can't serialize the store cipher"))
}
fn import_helper(key: &ChachaKey, encrypted: EncryptedStoreCipher) -> Result<Self, Error> {
let mut decrypted = match encrypted.ciphertext_info {
CipherTextInfo::ChaCha20Poly1305 { nonce, ciphertext } => {
let cipher = XChaCha20Poly1305::new(key);
let nonce = XNonce::from_slice(&nonce);
cipher.decrypt(nonce, ciphertext.as_ref())?
}
};
if decrypted.len() != 64 {
decrypted.zeroize();
Err(Error::Length(64, decrypted.len()))
} else {
let mut encryption_key = Box::new([0u8; 32]);
let mut mac_key_seed = Box::new([0u8; 32]);
encryption_key.copy_from_slice(&decrypted[0..32]);
mac_key_seed.copy_from_slice(&decrypted[32..64]);
let keys = Keys { encryption_key, mac_key_seed };
decrypted.zeroize();
Ok(Self { inner: keys })
}
}
/// Restore a store cipher from an export encrypted with a passphrase.
///
/// # Arguments
///
/// * `passphrase` - The passphrase that was used to encrypt the store
/// cipher.
///
/// * `encrypted` - The exported and encrypted version of the store cipher.
///
/// # Examples
///
/// ```rust,no_run
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::json;
///
/// let store_cipher = StoreCipher::new()?;
///
/// // Export the store cipher and persist it in your key/value store
/// let export = store_cipher.export("secret-passphrase")?;
///
/// // This is now the same as `store_cipher`.
/// let imported = StoreCipher::import("secret-passphrase", &export)?;
///
/// // Save the export in your key/value store.
/// # anyhow::Ok(()) };
/// ```
pub fn import(passphrase: &str, encrypted: &[u8]) -> Result<Self, Error> {
// Our old export format used serde_json for the serialization format. Let's
// first try the new format and if that fails, try the old one.
let encrypted: EncryptedStoreCipher =
if let Ok(deserialized) = rmp_serde::from_slice(encrypted) {
deserialized
} else {
serde_json::from_slice(encrypted)?
};
let key = match encrypted.kdf_info {
KdfInfo::Pbkdf2ToChaCha20Poly1305 { rounds, kdf_salt } => {
Self::expand_key(passphrase, &kdf_salt, rounds)
}
KdfInfo::None => {
return Err(Error::KdfMismatch);
}
};
let key = ChachaKey::from_slice(key.as_ref());
Self::import_helper(key, encrypted)
}
/// Restore a store cipher from an export encrypted with a random key.
///
/// # Arguments
///
/// * `key` - The 32-byte decryption key that was previously used to encrypt
/// the store cipher.
///
/// * `encrypted` - The exported and encrypted version of the store cipher.
///
/// # Examples
///
/// ```rust,no_run
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::json;
///
/// let store_cipher = StoreCipher::new()?;
///
/// // Export the store cipher and persist it in your key/value store
/// let export = store_cipher.export_with_key(&[0u8; 32])?;
///
/// // This is now the same as `store_cipher`.
/// let imported = StoreCipher::import_with_key(&[0u8; 32], &export)?;
///
/// // Save the export in your key/value store.
/// # anyhow::Ok(()) };
/// ```
pub fn import_with_key(key: &[u8; 32], encrypted: &[u8]) -> Result<Self, Error> {
let encrypted: EncryptedStoreCipher = rmp_serde::from_slice(encrypted).unwrap();
if let KdfInfo::Pbkdf2ToChaCha20Poly1305 { .. } = encrypted.kdf_info {
return Err(Error::KdfMismatch);
};
let key = ChachaKey::from_slice(key.as_ref());
Self::import_helper(key, encrypted)
}
/// Hash a key before it is inserted into the key/value store.
///
/// This prevents the key names from leaking to parties which do not have
/// the ability to decrypt the key/value store.
///
/// # Arguments
///
/// * `table_name` - The name of the key/value table this key will be
/// inserted into. This can also contain additional unique data. It will
/// be used to derive a table-specific cryptographic key which will be
/// used in a keyed hash function. This ensures data independence between
/// the different tables of the key/value store.
///
/// * `key` - The key to be hashed, prior to insertion into the key/value
/// store.
///
/// **Note**: This is a one-way transformation; you cannot obtain the
/// original key from its hash.
///
/// # Examples
///
/// ```rust,no_run
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::json;
///
/// let store_cipher = StoreCipher::new()?;
///
/// let key = "bulbasaur";
///
/// // Hash the key so people don't know which pokemon we have collected.
/// let hashed_key = store_cipher.hash_key("list-of-pokemon", key.as_ref());
///
/// // It's now safe to insert the key into our key/value store.
/// # anyhow::Ok(()) };
/// ```
pub fn hash_key(&self, table_name: &str, key: &[u8]) -> [u8; 32] {
let mac_key = self.inner.get_mac_key_for_table(table_name);
mac_key.mac(key).into()
}
/// Encrypt a value before it is inserted into the key/value store.
///
/// A value can be decrypted using the [`StoreCipher::decrypt_value()`]
/// method.
///
/// # Arguments
///
/// * `value` - A value that should be encrypted, any value that implements
/// `Serialize` can be given to this method. The value will be serialized
/// as json before it is encrypted.
///
/// # Examples
///
/// ```rust,no_run
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = json!({
/// "some": "data",
/// });
///
/// let encrypted = store_cipher.encrypt_value(&value)?;
/// let decrypted: Value = store_cipher.decrypt_value(&encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn encrypt_value(&self, value: &impl Serialize) -> Result<Vec<u8>, Error> {
let data = serde_json::to_vec(value)?;
Ok(serde_json::to_vec(&self.encrypt_value_data(data)?)?)
}
/// Encrypt some data before it is inserted into the key/value store.
///
/// A value can be decrypted using the [`StoreCipher::decrypt_value_data()`]
/// method. This is the lower level function to `encrypt_value`
///
/// # Arguments
///
/// * `data` - A value that should be encrypted, encoded as a `Vec<u8>`
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = serde_json::to_vec(&json!({
/// "some": "data",
/// }))?;
///
/// let encrypted = store_cipher.encrypt_value_data(value.clone())?;
/// let decrypted = store_cipher.decrypt_value_data(encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn encrypt_value_data(&self, mut data: Vec<u8>) -> Result<EncryptedValue, Error> {
let nonce = Keys::get_nonce()?;
let cipher = XChaCha20Poly1305::new(self.inner.encryption_key());
let ciphertext = cipher.encrypt(XNonce::from_slice(&nonce), data.as_ref())?;
data.zeroize();
Ok(EncryptedValue { version: VERSION, ciphertext, nonce })
}
/// Encrypt some data before it is inserted into the key/value store,
/// using base64 for arrays of integers.
///
/// A value can be decrypted using the
/// [`StoreCipher::decrypt_value_base64_data()`] method.
///
/// # Arguments
///
/// * `data` - A value that should be encrypted, encoded as a `Vec<u8>`
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = serde_json::to_vec(&json!({
/// "some": "data",
/// }))?;
///
/// let encrypted = store_cipher.encrypt_value_base64_data(value.clone())?;
/// let decrypted = store_cipher.decrypt_value_base64_data(encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn encrypt_value_base64_data(&self, data: Vec<u8>) -> Result<EncryptedValueBase64, Error> {
self.encrypt_value_data(data).map(EncryptedValueBase64::from)
}
/// Decrypt a value after it was fetched from the key/value store.
///
/// A value can be encrypted using the [`StoreCipher::encrypt_value()`]
/// method.
///
/// # Arguments
///
/// * `value` - The ciphertext of a value that should be decrypted.
///
/// The method will deserialize the decrypted value into the expected type.
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = json!({
/// "some": "data",
/// });
///
/// let encrypted = store_cipher.encrypt_value(&value)?;
/// let decrypted: Value = store_cipher.decrypt_value(&encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn decrypt_value<T: DeserializeOwned>(&self, value: &[u8]) -> Result<T, Error> {
let value: EncryptedValue = serde_json::from_slice(value)?;
let mut plaintext = self.decrypt_value_data(value)?;
let ret = serde_json::from_slice(&plaintext);
plaintext.zeroize();
Ok(ret?)
}
/// Decrypt a base64-encoded value after it was fetched from the key/value
/// store.
///
/// A value can be encrypted using the
/// [`StoreCipher::encrypt_value_base64_data()`] method.
///
/// # Arguments
///
/// * `value` - The EncryptedValueBase64 of a value that should be
/// decrypted.
///
/// The method will return the raw decrypted value
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = serde_json::to_vec(&json!({
/// "some": "data",
/// }))?;
///
/// let encrypted = store_cipher.encrypt_value_base64_data(value.clone())?;
/// let decrypted = store_cipher.decrypt_value_base64_data(encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn decrypt_value_base64_data(&self, value: EncryptedValueBase64) -> Result<Vec<u8>, Error> {
self.decrypt_value_data(value.try_into()?)
}
/// Decrypt a value after it was fetched from the key/value store.
///
/// A value can be encrypted using the [`StoreCipher::encrypt_value_data()`]
/// method. Lower level method to [`StoreCipher::decrypt_value()`].
///
/// # Arguments
///
/// * `value` - The EncryptedValue of a value that should be decrypted.
///
/// The method will return the raw decrypted value
///
/// # Examples
///
/// ```
/// # let example = || {
/// use matrix_sdk_store_encryption::StoreCipher;
/// use serde_json::{json, value::Value};
///
/// let store_cipher = StoreCipher::new()?;
///
/// let value = serde_json::to_vec(&json!({
/// "some": "data",
/// }))?;
///
/// let encrypted = store_cipher.encrypt_value_data(value.clone())?;
/// let decrypted = store_cipher.decrypt_value_data(encrypted)?;
///
/// assert_eq!(value, decrypted);
/// # anyhow::Ok(()) };
/// ```
pub fn decrypt_value_data(&self, value: EncryptedValue) -> Result<Vec<u8>, Error> {
if value.version != VERSION {
return Err(Error::Version(VERSION, value.version));
}
let cipher = XChaCha20Poly1305::new(self.inner.encryption_key());
let nonce = XNonce::from_slice(&value.nonce);
Ok(cipher.decrypt(nonce, value.ciphertext.as_ref())?)
}
/// Expand the given passphrase into a KEY_SIZE long key.
fn expand_key(passphrase: &str, salt: &[u8], rounds: u32) -> Box<[u8; 32]> {
let mut key = Box::new([0u8; 32]);
pbkdf2::<Hmac<Sha256>>(passphrase.as_bytes(), salt, rounds, key.deref_mut()).expect(
"We should be able to expand a passphrase of any length due to \
HMAC being able to be initialized with any input size",
);
key
}
}
#[derive(ZeroizeOnDrop)]
struct MacKey(Box<[u8; 32]>);
impl MacKey {
fn mac(&self, input: &[u8]) -> Hash {
blake3::keyed_hash(&self.0, input)
}
}
/// Encrypted value, ready for storage, as created by the
/// [`StoreCipher::encrypt_value_data()`]
#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
pub struct EncryptedValue {
version: u8,
ciphertext: Vec<u8>,
nonce: [u8; XNONCE_SIZE],
}
/// An error representing a failure to decode and encrypted value from base64
/// back into a `Vec<u8>`.
#[derive(Debug)]
pub enum EncryptedValueBase64DecodeError {
/// Base64 decoding failed because the string was not valid base64
DecodeError(base64::DecodeSliceError),
/// Decoding the nonce failed because it was not the expected length
IncorrectNonceLength(usize),
}
impl std::fmt::Display for EncryptedValueBase64DecodeError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let msg = match self {
EncryptedValueBase64DecodeError::DecodeError(e) => e.to_string(),
EncryptedValueBase64DecodeError::IncorrectNonceLength(length) => {
format!("Incorrect nonce length {}. Expected length: {}.", length, XNONCE_SIZE)
}
};
f.write_str(&msg)
}
}
impl From<base64::DecodeSliceError> for EncryptedValueBase64DecodeError {
fn from(value: base64::DecodeSliceError) -> Self {
Self::DecodeError(value)
}
}
impl From<base64::DecodeError> for EncryptedValueBase64DecodeError {
fn from(value: base64::DecodeError) -> Self {
Self::DecodeError(value.into())
}
}
impl From<Vec<u8>> for EncryptedValueBase64DecodeError {
fn from(value: Vec<u8>) -> Self {
Self::IncorrectNonceLength(value.len())
}
}
impl From<EncryptedValueBase64DecodeError> for Error {
fn from(value: EncryptedValueBase64DecodeError) -> Self {
Error::Deserialization(rmp_serde::decode::Error::Uncategorized(value.to_string()))
}
}
impl TryFrom<EncryptedValueBase64> for EncryptedValue {
type Error = EncryptedValueBase64DecodeError;
fn try_from(value: EncryptedValueBase64) -> Result<Self, Self::Error> {
let mut nonce = [0; XNONCE_SIZE];
BASE64.decode_slice(value.nonce, &mut nonce)?;
Ok(Self { version: value.version, ciphertext: BASE64.decode(value.ciphertext)?, nonce })
}
}
/// Encrypted value, ready for storage, as created by the
/// [`StoreCipher::encrypt_value_base64_data()`]
#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
pub struct EncryptedValueBase64 {
version: u8,
ciphertext: String,
nonce: String,
}
impl EncryptedValueBase64 {
/// Create a new EncryptedValueBase64
pub fn new(version: u8, ciphertext: &str, nonce: &str) -> Self {
Self { version, ciphertext: ciphertext.to_owned(), nonce: nonce.to_owned() }
}
}
impl From<EncryptedValue> for EncryptedValueBase64 {
fn from(value: EncryptedValue) -> Self {
Self {
version: value.version,
ciphertext: BASE64.encode(value.ciphertext),
nonce: BASE64.encode(value.nonce),
}
}
}
#[derive(ZeroizeOnDrop)]
struct Keys {
encryption_key: Box<[u8; 32]>,
mac_key_seed: Box<MacKeySeed>,
}
impl Keys {
fn new() -> Result<Self, Error> {
let mut encryption_key = Box::new([0u8; 32]);
let mut mac_key_seed = Box::new([0u8; 32]);
let mut rng = thread_rng();
encryption_key.try_fill(&mut rng)?;
mac_key_seed.try_fill(&mut rng)?;
Ok(Self { encryption_key, mac_key_seed })
}
fn encryption_key(&self) -> &ChachaKey {
ChachaKey::from_slice(self.encryption_key.as_slice())
}
fn mac_key_seed(&self) -> &MacKeySeed {
&self.mac_key_seed
}
fn get_mac_key_for_table(&self, table_name: &str) -> MacKey {
let mut key = MacKey(Box::new([0u8; 32]));
let mut output = derive_key(table_name, self.mac_key_seed());
key.0.copy_from_slice(&output);
output.zeroize();
key
}
fn get_nonce() -> Result<[u8; XNONCE_SIZE], RandomError> {
let mut nonce = [0u8; XNONCE_SIZE];
let mut rng = thread_rng();
nonce.try_fill(&mut rng)?;
Ok(nonce)
}
}
/// Version specific info for the key derivation method that is used.
#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
enum KdfInfo {
None,
/// The PBKDF2 to Chacha key derivation variant.
Pbkdf2ToChaCha20Poly1305 {
/// The number of PBKDF rounds that were used when deriving the store
/// key.
rounds: u32,
/// The salt that was used when the passphrase was expanded into a store
/// key.
kdf_salt: [u8; KDF_SALT_SIZE],
},
}
/// Version specific info for encryption method that is used to encrypt our
/// store cipher.
#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
enum CipherTextInfo {
/// A store cipher encrypted using the ChaCha20Poly1305 AEAD.
ChaCha20Poly1305 {
/// The nonce that was used to encrypt the ciphertext.
nonce: [u8; XNONCE_SIZE],
/// The encrypted store cipher.
ciphertext: Vec<u8>,
},
}
/// An encrypted version of our store cipher, this can be safely stored in a
/// database.
#[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
struct EncryptedStoreCipher {
/// Info about the key derivation method that was used to expand the
/// passphrase into an encryption key.
pub kdf_info: KdfInfo,
/// The ciphertext with it's accompanying additional data that is needed to
/// decrypt the store cipher.
pub ciphertext_info: CipherTextInfo,
}
#[cfg(test)]
mod tests {
use serde_json::{json, Value};
use super::{Error, StoreCipher};
use crate::{EncryptedValue, EncryptedValueBase64, EncryptedValueBase64DecodeError};
#[test]
fn generating() {
StoreCipher::new().unwrap();
}
#[test]
fn exporting_store_cipher() -> Result<(), Error> {
let passphrase = "it's a secret to everybody";
let store_cipher = StoreCipher::new()?;
let value = json!({
"some": "data"
});
let encrypted_value = store_cipher.encrypt_value(&value)?;
let encrypted = store_cipher._insecure_export_fast_for_testing(passphrase)?;
let decrypted = StoreCipher::import(passphrase, &encrypted)?;
assert_eq!(store_cipher.inner.encryption_key, decrypted.inner.encryption_key);
assert_eq!(store_cipher.inner.mac_key_seed, decrypted.inner.mac_key_seed);
let decrypted_value: Value = decrypted.decrypt_value(&encrypted_value)?;
assert_eq!(value, decrypted_value);
// Can't use assert matches here since we don't have a Debug implementation for
// StoreCipher.
match StoreCipher::import_with_key(&[0u8; 32], &encrypted) {
Err(Error::KdfMismatch) => {}
_ => panic!(
"Invalid error when importing a passphrase-encrypted store cipher with a key"
),
}
let store_cipher = StoreCipher::new()?;
let encrypted_value = store_cipher.encrypt_value(&value)?;
let export = store_cipher.export_with_key(&[0u8; 32])?;
let decrypted = StoreCipher::import_with_key(&[0u8; 32], &export)?;
let decrypted_value: Value = decrypted.decrypt_value(&encrypted_value)?;
assert_eq!(value, decrypted_value);
// Same as above, can't use assert_matches.
match StoreCipher::import_with_key(&[0u8; 32], &encrypted) {
Err(Error::KdfMismatch) => {}
_ => panic!(
"Invalid error when importing a key-encrypted store cipher with a passphrase"
),
}
let old_export = json!({
"ciphertext_info": {
"ChaCha20Poly1305":{
"ciphertext":[
136,202,212,194,9,223,171,109,152,84,140,183,14,55,198,22,150,130,80,135,
161,202,79,205,151,202,120,91,108,154,252,94,56,178,108,216,186,179,167,128,
154,107,243,195,14,138,86,78,140,159,245,170,204,227,27,84,255,161,196,69,
60,150,69,123,67,134,28,50,10,179,250,141,221,19,202,132,28,122,92,116
],
"nonce":[
108,3,115,54,65,135,250,188,212,204,93,223,78,11,52,46,
124,140,218,73,88,167,50,230
]
}
},
"kdf_info":{
"Pbkdf2ToChaCha20Poly1305":{
"kdf_salt":[
221,133,149,116,199,122,172,189,236,42,26,204,53,164,245,158,137,113,
31,220,239,66,64,51,242,164,185,166,176,218,209,245
],
"rounds":1000
}
}
});
let old_export = serde_json::to_vec(&old_export)?;
StoreCipher::import(passphrase, &old_export)
.expect("We can import the old store-cipher export");
Ok(())
}
#[test]
fn encrypting_values() -> Result<(), Error> {
let event = json!({
"content": {
"body": "Bee Gees - Stayin' Alive",
"info": {
"duration": 2140786u32,
"mimetype": "audio/mpeg",
"size": 1563685u32
},
"msgtype": "m.audio",
"url": "mxc://example.org/ffed755USFFxlgbQYZGtryd"
},
});
let store_cipher = StoreCipher::new()?;
let encrypted = store_cipher.encrypt_value(&event)?;
let decrypted: Value = store_cipher.decrypt_value(&encrypted)?;
assert_eq!(event, decrypted);
Ok(())
}
#[test]
fn encrypting_values_base64() -> Result<(), Error> {
let event = json!({
"content": {
"body": "Bee Gees - Stayin' Alive",
"info": {
"duration": 2140786u32,
"mimetype": "audio/mpeg",
"size": 1563685u32
},
"msgtype": "m.audio",
"url": "mxc://example.org/ffed755USFFxlgbQYZGtryd"
},
});
let store_cipher = StoreCipher::new()?;
let data = serde_json::to_vec(&event)?;
let encrypted = store_cipher.encrypt_value_base64_data(data)?;
let plaintext = store_cipher.decrypt_value_base64_data(encrypted)?;
let decrypted: Value = serde_json::from_slice(&plaintext)?;
assert_eq!(event, decrypted);
Ok(())
}
#[test]
fn encrypting_keys() -> Result<(), Error> {
let store_cipher = StoreCipher::new()?;
let first = store_cipher.hash_key("some_table", b"It's dangerous to go alone");
let second = store_cipher.hash_key("some_table", b"It's dangerous to go alone");
let third = store_cipher.hash_key("another_table", b"It's dangerous to go alone");
let fourth = store_cipher.hash_key("another_table", b"It's dangerous to go alone");
let fifth = store_cipher.hash_key("another_table", b"It's not dangerous to go alone");
assert_eq!(first, second);
assert_ne!(first, third);
assert_eq!(third, fourth);
assert_ne!(fourth, fifth);
Ok(())
}
#[test]
fn can_round_trip_normal_to_base64_encrypted_values() {
let normal1 = EncryptedValue { version: 2, ciphertext: vec![1, 2, 4], nonce: make_nonce() };
let normal2 = EncryptedValue { version: 2, ciphertext: vec![1, 2, 4], nonce: make_nonce() };
// We can convert to base 64 and the result looks as expected
let base64: EncryptedValueBase64 = normal1.into();
assert_eq!(base64.ciphertext, "AQIE");
// The round trip leaves it unchanged
let new_normal: EncryptedValue = base64.try_into().unwrap();
assert_eq!(normal2, new_normal);
}
#[test]
fn can_round_trip_base64_to_normal_encrypted_values() {
let base64_1 = EncryptedValueBase64 {
version: 2,
ciphertext: "abc".to_owned(),
nonce: make_nonce_base64(),
};
let base64_2 = EncryptedValueBase64 {
version: 2,
ciphertext: "abc".to_owned(),
nonce: make_nonce_base64(),
};
// We can convert to normal and the result looks as expected
let normal: EncryptedValue = base64_1.try_into().unwrap();
assert_eq!(normal.ciphertext, &[105, 183]);
// The round trip leaves it unchanged
let new_base64: EncryptedValueBase64 = normal.into();
assert_eq!(base64_2, new_base64);
}
#[test]
fn decoding_invalid_base64_returns_an_error() {
let base64 =
EncryptedValueBase64 { version: 2, ciphertext: "a".to_owned(), nonce: "b".to_owned() };
let result: Result<EncryptedValue, EncryptedValueBase64DecodeError> = base64.try_into();
let Err(err) = result else {
panic!("Should be an error!");
};
assert_eq!(err.to_string(), "DecodeError: Invalid input length: 1");
}
fn make_nonce() -> [u8; 24] {
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23]
}
fn make_nonce_base64() -> String {
"AAECAwQFBgcICQoLDA0ODxAREhMUFRYX".to_owned()
}
}