[PLATFORM-1854]: Fix encryption (#164)

CHANGELOG.md

@@ -8,6 +8,12 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Security
+
+- Switched to using XChaCha20Poly1305 for the redis token cache encryption.
+
+This addresses a few medium severity security issues with the tokens
+
 ---
 
 ## [0.16.4] - 2024-07-04

Cargo.toml

@@ -13,7 +13,7 @@ rust-version = "1.72"
 [features]
 default = ["tracing_opentelemetry"]
 
-auth0 = ["rand", "redis", "jsonwebtoken", "jwks_client_rs", "chrono", "aes", "cbc", "dashmap", "tracing"]
+auth0 = ["rand", "redis", "jsonwebtoken", "jwks_client_rs", "chrono", "chacha20poly1305", "dashmap", "tracing"]
 gzip = ["reqwest/gzip"]
 redis-tls = ["redis/tls", "redis/tokio-native-tls-comp"]
 tracing_opentelemetry = [ "tracing_opentelemetry_0_23" ]
@@ -26,10 +26,8 @@ tracing_opentelemetry_0_23 = ["_any_otel_version", "tracing", "tracing-opentelem
 _any_otel_version = []
 
 [dependencies]
-aes = {version = "0.8", optional = true}
 async-trait = "0.1"
 bytes = "1.2"
-cbc = {version = "0.1", features = ["std"], optional = true}
 chrono = {version = "0.4", default-features = false, features = ["clock", "std", "serde"], optional = true}
 dashmap = {version = "6.0", optional = true}
 futures = "0.3"
@@ -45,6 +43,7 @@ thiserror = "1.0"
 tokio = {version = "1.16", features = ["macros", "rt-multi-thread", "fs"]}
 tracing = {version = "0.1", optional = true}
 uuid = {version = ">=0.7.0, <2.0.0", features = ["serde", "v4"]}
+chacha20poly1305 = { version = "0.10.1", features = ["std"], optional = true }
 
 reqwest-middleware = { version = "0.3.0", features = ["json", "multipart"] }
 http = "1.0.0"

src/auth0/cache/crypto.rs

@@ -1,35 +1,37 @@
-use aes::{
-    cipher::{block_padding::Pkcs7, BlockDecryptMut, BlockEncryptMut, KeyIvInit},
-    Aes256,
-};
-use cbc::{Decryptor, Encryptor};
+use chacha20poly1305::{aead::Aead, AeadCore, KeyInit, XChaCha20Poly1305};
+use rand::thread_rng;
 use serde::{Deserialize, Serialize};
 
 use crate::auth0::errors::Auth0Error;
 
-type Aes256Enc = Encryptor<Aes256>;
-type Aes256Dec = Decryptor<Aes256>;
-
-const IV: &str = "301a9e39735f4646";
+const NONCE_SIZE: usize = 24;
 
 pub fn encrypt<T: Serialize>(value_ref: &T, token_encryption_key_str: &str) -> Result<Vec<u8>, Auth0Error> {
     let json: String = serde_json::to_string(value_ref)?;
 
-    let ct = Aes256Enc::new(token_encryption_key_str.as_bytes().into(), IV.as_bytes().into())
-        .encrypt_padded_vec_mut::<Pkcs7>(json.as_bytes());
+    let enc = XChaCha20Poly1305::new_from_slice(token_encryption_key_str.as_bytes()).unwrap();
+    let nonce = XChaCha20Poly1305::generate_nonce(&mut thread_rng());
+
+    let mut ciphertext = enc.encrypt(&nonce, json.as_bytes())?;
+    ciphertext.extend(nonce);
 
-    Ok(ct.to_vec())
+    Ok(ciphertext)
 }
 
 pub fn decrypt<T>(token_encryption_key_str: &str, encrypted: &[u8]) -> Result<T, Auth0Error>
 where
     for<'de> T: Deserialize<'de>,
 {
-    // `unwrap` here is fine because `IV` is set here and the only error returned is: `InvalidKeyIvLength`
-    // and this must never happen
-    let pt = Aes256Dec::new(token_encryption_key_str.as_bytes().into(), IV.as_bytes().into())
-        .decrypt_padded_vec_mut::<Pkcs7>(encrypted)
-        .unwrap();
+    let dec = XChaCha20Poly1305::new_from_slice(token_encryption_key_str.as_bytes()).unwrap();
+
+    let ciphertext = encrypted.get(..encrypted.len() - NONCE_SIZE);
+    let nonce = encrypted.get(encrypted.len() - NONCE_SIZE..);
+
+    let (Some(ciphertext), Some(nonce)) = (ciphertext, nonce) else {
+        return Err(Auth0Error::CryptoError(chacha20poly1305::Error));
+    };
 
-    Ok(serde_json::from_slice(&pt)?)
+    let nonce = chacha20poly1305::XNonce::from_slice(nonce);
+    let plaintext = dec.decrypt(nonce, ciphertext)?;
+    Ok(serde_json::from_slice(&plaintext)?)
 }

src/auth0/cache/redis_impl.rs

@@ -53,7 +53,7 @@ impl Cache for RedisCache {
         let mut connection = self.client.get_async_connection().await?;
         let encrypted_value: Vec<u8> = crypto::encrypt(value_ref, self.encryption_key.as_str())?;
         let expiration: usize = value_ref.lifetime_in_seconds();
-        connection.set_ex(key, encrypted_value, expiration).await?;
+        let _: () = connection.set_ex(key, encrypted_value, expiration).await?;
         Ok(())
     }
 }

src/auth0/errors.rs

@@ -1,4 +1,3 @@
-use aes::cipher::block_padding::UnpadError;
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -18,5 +17,5 @@ pub enum Auth0Error {
     #[error("redis error: {0}")]
     RedisError(#[from] redis::RedisError),
     #[error(transparent)]
-    CryptoError(#[from] UnpadError),
+    CryptoError(#[from] chacha20poly1305::Error),
 }

src/request/request_type/graphql.rs

@@ -60,7 +60,7 @@ impl<'a, Client: BridgeClient> GraphQLRequest<'a, Client> {
     ) -> PrimaBridgeResult<Self> {
         // No content-type here because Form set it at `multipart/form-data` with extra params for
         // disposition
-        let json_body = serde_json::to_value(&graphql_body.into())?;
+        let json_body = serde_json::to_value(graphql_body.into())?;
         let body_with_injected_variables = match &multipart {
             GraphQLMultipart::Single(single) => {
                 let path: VecDeque<&str> = single.path.split('.').collect();