From a76b21bfa2a69e61790087ee8a5c74ce6c2eeee4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Garci=CC=81a?=
 <dani-garcia@users.noreply.github.com>
Date: Tue, 6 Feb 2024 19:06:25 +0100
Subject: [PATCH] Add support for missing AES decrypt types

---
 crates/bitwarden-crypto/src/aes.rs            | 40 ++++++++++++++++++-
 .../src/enc_string/symmetric.rs               | 15 ++++++-
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/crates/bitwarden-crypto/src/aes.rs b/crates/bitwarden-crypto/src/aes.rs
index 195b818b7..bf433114d 100644
--- a/crates/bitwarden-crypto/src/aes.rs
+++ b/crates/bitwarden-crypto/src/aes.rs
@@ -6,7 +6,9 @@
 //! [KeyEncryptable][crate::KeyEncryptable] & [KeyDecryptable][crate::KeyDecryptable] instead.
 
 use aes::cipher::{
-    block_padding::Pkcs7, typenum::U32, BlockDecryptMut, BlockEncryptMut, KeyIvInit,
+    block_padding::Pkcs7,
+    typenum::{U16, U32},
+    BlockDecryptMut, BlockEncryptMut, KeyIvInit,
 };
 use generic_array::GenericArray;
 use hmac::Mac;
@@ -109,6 +111,42 @@ fn encrypt_aes256_internal(
     (iv, data)
 }
 
+/// Decrypt using AES-128 in CBC mode.
+///
+/// Behaves similar to [decrypt_aes128_hmac], but does not validate the MAC.
+fn decrypt_aes128(iv: &[u8; 16], data: Vec<u8>, key: &GenericArray<u8, U16>) -> Result<Vec<u8>> {
+    // Decrypt data
+    let iv = GenericArray::from_slice(iv);
+    let mut data = data;
+    let decrypted_key_slice = cbc::Decryptor::<aes::Aes128>::new(key, iv)
+        .decrypt_padded_mut::<Pkcs7>(&mut data)
+        .map_err(|_| CryptoError::KeyDecrypt)?;
+
+    // Data is decrypted in place and returns a subslice of the original Vec, to avoid cloning it,
+    // we truncate to the subslice length
+    let decrypted_len = decrypted_key_slice.len();
+    data.truncate(decrypted_len);
+
+    Ok(data)
+}
+
+/// Decrypt using AES-128 in CBC mode with MAC.
+///
+/// Behaves similar to [decrypt_aes128], but also validates the MAC.
+pub fn decrypt_aes128_hmac(
+    iv: &[u8; 16],
+    mac: &[u8; 32],
+    data: Vec<u8>,
+    mac_key: &GenericArray<u8, U16>,
+    key: &GenericArray<u8, U16>,
+) -> Result<Vec<u8>> {
+    let res = generate_mac(mac_key, iv, &data)?;
+    if res.ct_ne(mac).into() {
+        return Err(CryptoError::InvalidMac);
+    }
+    decrypt_aes128(iv, data, key)
+}
+
 /// Generate a MAC using HMAC-SHA256.
 fn generate_mac(mac_key: &[u8], iv: &[u8], data: &[u8]) -> Result<[u8; 32]> {
     let mut hmac = PbkdfSha256Hmac::new_from_slice(mac_key).expect("HMAC can take key of any size");
diff --git a/crates/bitwarden-crypto/src/enc_string/symmetric.rs b/crates/bitwarden-crypto/src/enc_string/symmetric.rs
index a7768de23..5d9d6ef97 100644
--- a/crates/bitwarden-crypto/src/enc_string/symmetric.rs
+++ b/crates/bitwarden-crypto/src/enc_string/symmetric.rs
@@ -236,13 +236,26 @@ impl KeyEncryptable<SymmetricCryptoKey, EncString> for &[u8] {
 impl KeyDecryptable<SymmetricCryptoKey, Vec<u8>> for EncString {
     fn decrypt_with_key(&self, key: &SymmetricCryptoKey) -> Result<Vec<u8>> {
         match self {
+            EncString::AesCbc256_B64 { iv, data } => {
+                let dec = crate::aes::decrypt_aes256(iv, data.clone(), &key.key)?;
+                Ok(dec)
+            }
+            EncString::AesCbc128_HmacSha256_B64 { iv, mac, data } => {
+                // TODO: SymmetricCryptoKey is designed to handle 32 byte keys only, but this
+                // variant uses a 16 byte key This means the key+mac are going to be
+                // parsed as a single 32 byte key, at the moment we split it manually
+                // When refactoring the key handling, this should be fixed.
+                let enc_key = key.key[0..16].into();
+                let mac_key = key.key[16..32].into();
+                let dec = crate::aes::decrypt_aes128_hmac(iv, mac, data.clone(), mac_key, enc_key)?;
+                Ok(dec)
+            }
             EncString::AesCbc256_HmacSha256_B64 { iv, mac, data } => {
                 let mac_key = key.mac_key.as_ref().ok_or(CryptoError::InvalidMac)?;
                 let dec =
                     crate::aes::decrypt_aes256_hmac(iv, mac, data.clone(), mac_key, &key.key)?;
                 Ok(dec)
             }
-            _ => Err(CryptoError::InvalidKey),
         }
     }
 }