Trusted Device Encryption (#497)

Implement trusted device encryption. Verified backwards compatibility
with existing device keys from desktop.

crates/bitwarden-crypto/src/enc_string/asymmetric.rs

@@ -7,6 +7,7 @@ use serde::Deserialize;
 use super::{from_b64_vec, split_enc_string};
 use crate::{
     error::{CryptoError, EncStringParseError, Result},
+    rsa::encrypt_rsa2048_oaep_sha1,
     AsymmetricCryptoKey, KeyDecryptable,
 };
 
@@ -137,6 +138,14 @@ impl serde::Serialize for AsymmetricEncString {
 }
 
 impl AsymmetricEncString {
+    pub(crate) fn encrypt_rsa2048_oaep_sha1(
+        data_dec: &[u8],
+        key: &AsymmetricCryptoKey,
+    ) -> Result<AsymmetricEncString> {
+        let enc = encrypt_rsa2048_oaep_sha1(&key.key, data_dec)?;
+        Ok(AsymmetricEncString::Rsa2048_OaepSha1_B64 { data: enc })
+    }
+
     /// The numerical representation of the encryption type of the [AsymmetricEncString].
     const fn enc_type(&self) -> u8 {
         match self {

crates/bitwarden-crypto/src/error.rs

@@ -52,6 +52,8 @@ pub enum RsaError {
     CreatePublicKey,
     #[error("Unable to create private key")]
     CreatePrivateKey,
+    #[error("Rsa error, {0}")]
+    Rsa(#[from] rsa::Error),
 }
 
 /// Alias for `Result<T, CryptoError>`.

crates/bitwarden-crypto/src/keys/asymmetric_crypto_key.rs

@@ -9,6 +9,15 @@ pub struct AsymmetricCryptoKey {
 }
 
 impl AsymmetricCryptoKey {
+    /// Generate a random AsymmetricCryptoKey (RSA-2048)
+    pub fn generate<R: rand::CryptoRng + rand::RngCore>(rng: &mut R) -> Self {
+        let bits = 2048;
+
+        Self {
+            key: RsaPrivateKey::new(rng, bits).expect("failed to generate a key"),
+        }
+    }
+
     pub fn from_pem(pem: &str) -> Result<Self> {
         use rsa::pkcs8::DecodePrivateKey;
         Ok(Self {

crates/bitwarden-crypto/src/keys/device_key.rs

@@ -0,0 +1,126 @@
+use crate::{
+    error::Result, AsymmetricCryptoKey, AsymmetricEncString, EncString, KeyDecryptable,
+    KeyEncryptable, SymmetricCryptoKey, UserKey,
+};
+
+/// Device Key
+///
+/// Encrypts the DevicePrivateKey
+/// Allows the device to decrypt the UserKey, via the DevicePrivateKey.
+#[derive(Debug)]
+pub struct DeviceKey(SymmetricCryptoKey);
+
+#[derive(Debug)]
+pub struct TrustDeviceResponse {
+    pub device_key: DeviceKey,
+    /// UserKey encrypted with DevicePublicKey
+    pub protected_user_key: AsymmetricEncString,
+    /// DevicePrivateKey encrypted with [DeviceKey]
+    pub protected_device_private_key: EncString,
+    /// DevicePublicKey encrypted with [UserKey](super::UserKey)
+    pub protected_device_public_key: EncString,
+}
+
+impl DeviceKey {
+    /// Generate a new device key
+    ///
+    /// Note: Input has to be a SymmetricCryptoKey instead of UserKey because that's what we get
+    /// from EncSettings.
+    pub fn trust_device(user_key: &SymmetricCryptoKey) -> Result<TrustDeviceResponse> {
+        let mut rng = rand::thread_rng();
+        let device_key = DeviceKey(SymmetricCryptoKey::generate(&mut rng));
+
+        let device_private_key = AsymmetricCryptoKey::generate(&mut rng);
+
+        // Encrypt both the key and mac_key of the user key
+        let data = user_key.to_vec();
+
+        let protected_user_key =
+            AsymmetricEncString::encrypt_rsa2048_oaep_sha1(&data, &device_private_key)?;
+
+        let protected_device_public_key = device_private_key
+            .to_public_der()?
+            .encrypt_with_key(user_key)?;
+
+        let protected_device_private_key = device_private_key
+            .to_der()?
+            .encrypt_with_key(&device_key.0)?;
+
+        Ok(TrustDeviceResponse {
+            device_key,
+            protected_user_key,
+            protected_device_private_key,
+            protected_device_public_key,
+        })
+    }
+
+    /// Decrypt the user key using the device key
+    pub fn decrypt_user_key(
+        &self,
+        protected_device_private_key: EncString,
+        protected_user_key: AsymmetricEncString,
+    ) -> Result<UserKey> {
+        let device_private_key: Vec<u8> = protected_device_private_key.decrypt_with_key(&self.0)?;
+        let device_private_key = AsymmetricCryptoKey::from_der(device_private_key.as_slice())?;
+
+        let dec: Vec<u8> = protected_user_key.decrypt_with_key(&device_private_key)?;
+        let user_key: SymmetricCryptoKey = dec.as_slice().try_into()?;
+
+        Ok(UserKey(user_key))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::derive_symmetric_key;
+
+    #[test]
+    fn test_trust_device() {
+        let key = derive_symmetric_key("test");
+
+        let result = DeviceKey::trust_device(&key).unwrap();
+
+        let decrypted = result
+            .device_key
+            .decrypt_user_key(
+                result.protected_device_private_key,
+                result.protected_user_key,
+            )
+            .unwrap();
+
+        assert_eq!(key.key, decrypted.0.key);
+        assert_eq!(key.mac_key, decrypted.0.mac_key);
+    }
+
+    #[test]
+    fn test_decrypt_user_key() {
+        // Example keys from desktop app
+        let user_key: &[u8] = &[
+            109, 128, 172, 147, 206, 123, 134, 95, 16, 36, 155, 113, 201, 18, 186, 230, 216, 212,
+            173, 188, 74, 11, 134, 131, 137, 242, 105, 178, 105, 126, 52, 139, 248, 91, 215, 21,
+            128, 91, 226, 222, 165, 67, 251, 34, 83, 81, 77, 147, 225, 76, 13, 41, 102, 45, 183,
+            218, 106, 89, 254, 208, 251, 101, 130, 10,
+        ];
+        let user_key = SymmetricCryptoKey::try_from(user_key).unwrap();
+
+        let key_data: &[u8] = &[
+            114, 235, 60, 115, 172, 156, 203, 145, 195, 130, 215, 250, 88, 146, 215, 230, 12, 109,
+            245, 222, 54, 217, 255, 211, 221, 105, 230, 236, 65, 52, 209, 133, 76, 208, 113, 254,
+            194, 216, 156, 19, 230, 62, 32, 93, 87, 7, 144, 156, 117, 142, 250, 32, 182, 118, 187,
+            8, 247, 7, 203, 201, 65, 147, 206, 247,
+        ];
+        let device_key = DeviceKey(key_data.try_into().unwrap());
+
+        let protected_user_key: AsymmetricEncString = "4.f+VbbacRhO2q4MOUSdt1AIjQ2FuLAvg4aDxJMXAh3VxvbmUADj8Ct/R7XEpPUqApmbRS566jS0eRVy8Sk08ogoCdj1IFN9VsIky2i2X1WHK1fUnr3UBmXE3tl2NPBbx56U+h73S2jNTSyet2W18Jg2q7/w8KIhR3J41QrG9aGoOTN93to3hb5W4z6rdrSI0e7GkizbwcIA0NH7Z1JyAhrjPm9+tjRjg060YbEbGaWTAOkZWfgbLjr8bY455DteO2xxG139cOx7EBo66N+YhjsLi0ozkeUyPQkoWBdKMcQllS7jCfB4fDyJA05ALTbk74syKkvqFxqwmQbg+aVn+dcw==".parse().unwrap();
+
+        let protected_device_private_key: EncString = "2.GyQfUYWW6Byy4UV5icFLxg==|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|JYdol19Yi+n1r7M+06EwK5JCi2s/CWqKui2Cy6hEb3k=".parse().unwrap();
+
+        let decrypted = device_key
+            .decrypt_user_key(protected_device_private_key, protected_user_key)
+            .unwrap();
+
+        assert_eq!(decrypted.0.key, user_key.key);
+        assert_eq!(decrypted.0.mac_key, user_key.mac_key);
+    }
+}

crates/bitwarden-crypto/src/keys/mod.rs

@@ -1,18 +1,16 @@
 mod key_encryptable;
 pub use key_encryptable::{KeyDecryptable, KeyEncryptable};
-
 mod master_key;
 pub use master_key::{HashPurpose, Kdf, MasterKey};
-
 mod shareable_key;
 pub use shareable_key::derive_shareable_key;
-
 mod symmetric_crypto_key;
 #[cfg(test)]
 pub use symmetric_crypto_key::derive_symmetric_key;
 pub use symmetric_crypto_key::SymmetricCryptoKey;
 mod asymmetric_crypto_key;
 pub use asymmetric_crypto_key::AsymmetricCryptoKey;
-
 mod user_key;
 pub use user_key::UserKey;
+mod device_key;
+pub use device_key::{DeviceKey, TrustDeviceResponse};

crates/bitwarden-crypto/src/rsa.rs

@@ -1,12 +1,13 @@
 use base64::{engine::general_purpose::STANDARD, Engine};
 use rsa::{
     pkcs8::{EncodePrivateKey, EncodePublicKey},
-    RsaPrivateKey, RsaPublicKey,
+    Oaep, RsaPrivateKey, RsaPublicKey,
 };
+use sha1::Sha1;
 
 use crate::{
     error::{Result, RsaError},
-    EncString, SymmetricCryptoKey,
+    CryptoError, EncString, SymmetricCryptoKey,
 };
 
 /// RSA Key Pair
@@ -42,3 +43,16 @@ pub(crate) fn make_key_pair(key: &SymmetricCryptoKey) -> Result<RsaKeyPair> {
         private: protected,
     })
 }
+
+pub(super) fn encrypt_rsa2048_oaep_sha1(
+    private_key: &RsaPrivateKey,
+    data: &[u8],
+) -> Result<Vec<u8>> {
+    let mut rng = rand::thread_rng();
+
+    let padding = Oaep::new::<Sha1>();
+    private_key
+        .to_public_key()
+        .encrypt(&mut rng, padding, data)
+        .map_err(|e| CryptoError::RsaError(e.into()))
+}

crates/bitwarden/src/auth/client_auth.rs

@@ -1,3 +1,6 @@
+#[cfg(feature = "internal")]
+use bitwarden_crypto::{DeviceKey, TrustDeviceResponse};
+
 #[cfg(feature = "secrets")]
 use crate::auth::login::{login_access_token, AccessTokenLoginRequest, AccessTokenLoginResponse};
 use crate::{auth::renew::renew_token, error::Result, Client};
@@ -16,6 +19,7 @@ use crate::{
         RegisterKeyResponse, RegisterRequest,
     },
     client::Kdf,
+    error::Error,
 };
 
 pub struct ClientAuth<'a> {
@@ -97,6 +101,19 @@ impl<'a> ClientAuth<'a> {
     pub async fn validate_password(&self, password: String, password_hash: String) -> Result<bool> {
         validate_password(self.client, password, password_hash).await
     }
+
+    pub async fn trust_device(&self) -> Result<TrustDeviceResponse> {
+        trust_device(self.client)
+    }
+}
+
+#[cfg(feature = "internal")]
+fn trust_device(client: &Client) -> Result<TrustDeviceResponse> {
+    let enc = client.get_encryption_settings()?;
+
+    let user_key = enc.get_key(&None).ok_or(Error::VaultLocked)?;
+
+    Ok(DeviceKey::trust_device(user_key)?)
 }
 
 impl<'a> Client {
@@ -172,7 +189,7 @@ mod tests {
             .login_access_token(&AccessTokenLoginRequest {
                 access_token: "0.ec2c1d46-6a4b-4751-a310-af9601317f2d.C2IgxjjLF7qSshsbwe8JGcbM075YXw:X8vbvA0bduihIDe/qrzIQQ==".into(),
                 state_file: None,
-            },)
+            })
             .await
             .unwrap();
         assert!(res.authenticated);