fix(biometrics): IOS keyhandling, timed keys on android (#323)

* IOS: Fixes handling of existing encryption keys when performing crypto options.
* Add methods to delete the keys on IOS/Android.
* Android: Add ability to configure time based keys on android, which allows crypto operations without triggering bio prompt if bio prompt has been complete X seconds previously.
* Android: make the didBiometricDatabaseChange operation have no side effects and support custom key name.

Author: jcassidyav

apps/demo/src/plugin-demos/biometrics.xml

@@ -22,18 +22,20 @@
 
                 <Button text="verify with encryption" tap="{{ doVerifyFingerprintWithEncrypt }}" class="btn btn-primary" />
                  <Button text="verify with decryption" tap="{{ doVerifyFingerprintWithDecrypt }}" class="btn btn-primary" />
+                 <Button text="delete Key" tap="{{ doDeleteKey }}" class="btn btn-primary" />
+                 
                  	<TextField text="{{ encryptedPassword }}" ></TextField>
                   <TextField text="{{ IV }}"></TextField>
                   <TextField text="{{ decryptedPassword }}"></TextField>
-              
+                  <TextField text="{{ androidKeyTimeout }}" ></TextField>
+                                
             </StackLayout>
           </ScrollView>
         </TabViewItem.view>
       </TabViewItem>
       <TabViewItem title="About">
         <TabViewItem.view>
           <StackLayout class="tab-content">
-            <Image margin="10" src="~/res/telerik-logo.png" />
             <Label text="Biometrics plugin demo" class="title"/>
             <Label text="The Biometrics plugin allows you to use the fingerprint / face scanner of your mobile device." textWrap="true"/>
             <Label text=" "/>

packages/biometrics/README.md

@@ -108,7 +108,7 @@ biometricAuth.available().then((avail) => {
 
 ### Normal operation
 
-If you do not pass any of the options (pinFallback / keyName) to the verify method then the plugin will create a secure key, call the authorization methods to trigger face/fingerprint and then attempt to use the key to encrypt some text. The idea being that the key will not be accessable unless the user has successfully authenticated.
+If you do not pass any of the options (pinFallback / keyName) to the verify method then the plugin will create a secure key, call the authorization methods to trigger face/fingerprint and then attempt to use the key to encrypt some text. The idea being that the key will not be accessible unless the user has successfully authenticated.
 
 This however is not foolproof and the most secure method is to pass the `secret` and `Keyname`options to encrypt/decrypt text.
 

packages/biometrics/common.ts

@@ -81,6 +81,11 @@ export interface AndroidOptions {
 	 * Retrieved from the result of an encryption.
 	 */
 	iv?: string;
+
+	/**
+	 * The period in seconds for which operations on the key are valid without triggering a biometric prompt.
+	 */
+	validityDuration?: number;
 }
 
 export interface BiometricIDAvailableResult {
@@ -117,9 +122,17 @@ export interface BiometricApi {
 	verifyBiometric(options: VerifyBiometricOptions): Promise<BiometricResult>;
 
 	/**
-	 * Note will not do anyting on android if using pin fallback.
+	 * Note will not do anything on android if using pin fallback.
 	 */
 	close(): void;
+
+	/**
+	 *
+	 * When using encryption backed biometrics keys are generated, this allow you to remove the key.
+	 *
+	 * @param keyName Optional keyName to delete, if not supplied will delete the default key.
+	 */
+	deleteKey(keyName?: string): void;
 }
 
 export interface BiometricResult {