[feat] [biometric] Adding the capability of encrypting/decrypting data using biometric authentication on Android (Ref. #2306) (#2454)

* –feat: adding the ability to encrypt/decrypt data based on the biometric auth

Adding the method biometricCipher() that allows to use the biometric authentication to use a generated key from android that can be accessed only through the biometric authentication. The method uses this key to encrypt/decrypt the data provided by the caller in the "options" parameter, with "dataToEncrypt" or "dataToDecrypt" filled.

Changes were done both on Kotlin, Rust and JS sides.

* Improving the way we encrypt data by allowing only if the biometric was successful.

* Adding a warning on the JS side

* Adding doc changes in readme.md

* Adding doc changes in readme.md

* Update README.md - it was updated incomplete

* update docs

* enhance error handling

* update example

---------

Co-authored-by: Lucas Nogueira <lucas@tauri.app>

plugins/biometric/src/commands.rs

@@ -33,6 +33,7 @@ pub(crate) async fn authenticate<R: Runtime>(
         title,
         subtitle,
         confirmation_required,
+        ..Default::default()
     };
     // The prompt blocks until the user answers, so keep it off the async runtime workers.
     tauri::async_runtime::spawn_blocking(move || app.biometric().authenticate(reason, options))

plugins/biometric/src/mobile.rs

@@ -53,4 +53,17 @@ impl<R: Runtime> Biometric<R> {
             .run_mobile_plugin("authenticate", AuthenticatePayload { reason, options })
             .map_err(Into::into)
     }
+
+    /// Prompts the user for biometric authentication and, on success, encrypts
+    /// [`AuthOptions::data_to_encrypt`] or decrypts [`AuthOptions::data_to_decrypt`] using a key
+    /// protected by the device's strong biometrics. **Android only.**
+    pub fn biometric_cipher(
+        &self,
+        reason: String,
+        options: AuthOptions,
+    ) -> crate::Result<CipherResult> {
+        self.0
+            .run_mobile_plugin("biometricCipher", AuthenticatePayload { reason, options })
+            .map_err(Into::into)
+    }
 }

plugins/biometric/src/models.rs

@@ -12,6 +12,10 @@ pub struct AuthOptions {
     pub allow_device_credential: bool,
     /// Label for the Cancel button. This feature is available on Android, iOS and macOS.
     pub cancel_title: Option<String>,
+    /// The plain data that must be encrypted after successful biometric authentication. **Android only.**
+    pub data_to_encrypt: Option<String>,
+    /// The encrypted data that must be decrypted after successful biometric authentication. **Android only.**
+    pub data_to_decrypt: Option<String>,
     /// Specifies the text displayed on the fallback button if biometric authentication fails. This feature is available on iOS and macOS only.
     pub fallback_title: Option<String>,
     /// Title indicating the purpose of biometric verification. This feature is available Android only.
@@ -50,3 +54,10 @@ pub struct Status {
     /// Only set when [`Self::is_available`] is `false`.
     pub error_code: Option<String>,
 }
+
+/// The result of [`Biometric::biometric_cipher`](crate::Biometric::biometric_cipher).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CipherResult {
+    /// The encrypted or decrypted data.
+    pub data: String,
+}