Biometric_Android Study

• 필요권한 AndroidManifest에 명시한다.

  <uses-permission
      android:name="android.permission.USE_BIOMETRIC" />

• AuthenticationCallback Object

  private val authenticationCallback: BiometricPrompt.AuthenticationCallback
  get() = object : BiometricPrompt.AuthenticationCallback(){
      override fun onAuthenticationError(errorCode: Int, errString: CharSequence?) {
          notifyUser("Authentication error: $errString")
          super.onAuthenticationError(errorCode, errString)
      }
  
      override fun onAuthenticationHelp(helpCode: Int, helpString: CharSequence?) {
          super.onAuthenticationHelp(helpCode, helpString)
      }
  
      override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult?) {
          notifyUser("Authentication Succeeded")
          super.onAuthenticationSucceeded(result)
      }
  
      override fun onAuthenticationFailed() {
          super.onAuthenticationFailed()
      }
  }

• 생체인증 팝업창

  fun authenticateUser(){
      val biometricPrompt = BiometricPrompt.Builder(this)
          .setTitle("Biometric Demo")
          .setSubtitle("Authentication is required to continue")
          .setDescription("This app uses biometric authentication to protect your data.")
          .setNegativeButton("Cancel", this.mainExecutor,
          DialogInterface.OnClickListener{dialogInterface, i->
  notifyUser("Authentication cancelled")
  }).build()
      biometricPrompt.authenticate(getCancellationSignal(),mainExecutor, authenticationCallback)
  }

• 권한확인 함수

  private fun checkBiometricSupport(): Boolean{
      val keyguardManager = getSystemService(Context.KEYGUARD_SERVICE)
          as KeyguardManager
  
      if(!keyguardManager.isKeyguardSecure){
          notifyUser("Lock screen security not enabled in Setting")
          return false
      }
  
      if(ActivityCompat.checkSelfPermission(
              this, Manifest.permission.USE_BIOMETRIC) !=
                  PackageManager.PERMISSION_GRANTED){
                      notifyUser("Fingerprint authentication permisson not enabled")
                      return false
      }
  
      return if(packageManager.hasSystemFeature(
              PackageManager.FEATURE_FINGERPRINT)){
          true
      } else true
  }

• Compose 이용한 버튼중앙 배치 코드

  @Composable
      fun widget_position(){
          Column(
              modifier = Modifier
                  .fillMaxWidth()
                  .fillMaxHeight(),
              verticalArrangement = Arrangement.Center,
              horizontalAlignment = Alignment.CenterHorizontally
          ){
              SimpleButton()
          }
      }
  
      @Composable
      fun SimpleButton(){
          //val context = LocalContext.current
          Button(onClick = {
              authenticateUser()
          }){
              Text(text = stringResource(id = R.string.authenticate))
          }
      }

• CancellationSignal object

  private var cancellationSignal: CancellationSignal? = null
  
      private fun getCancellationSignal() : CancellationSignal {
          cancellationSignal = CancellationSignal()
          cancellationSignal?.setOnCancelListener {
              notifyUser("Cancelled via signal")
          }
          return cancellationSignal as CancellationSignal
      }