Luciano Balmaceda lbalmaceda

Auth0 Fingerprint API

Create a new instance

The context is needed to access the check for availability

public class Auth0Fingerprint implements FingerprintManager.AuthenticationCallback {

  private final FingerprintManagerCompat manager;

CredentialsManager

Recently we introduced a helper class available here to handle Auth0 Credentials. Usage is simple: Once you create a new instance by passing an AuthenticationAPIClient (to renew credentials) and a Storage (to do persistance), you can call any of this 2 public methods:

saveCredentials: To synchronously save a pair of credentials in the storage. Will throw if the access_token or id_token is null, or if the expires_at date is missing.
getCredentials: To asynchronously get a pair of credentials from the storage.
- If no credentials were stored before the methods fails.
- If stored credentials have expired (expires_at > now) and no refresh_token was saved the method fails.
- If the call to renew the credentials using the refresh_token fails, the method fails.
In any other case, a valid pair of credentials is ret

Authenticated CredentialsManager

The simple credentials manager receives a pair of Credentials and perform:

Storage of the values (either 1 by 1 or all together in a single operation)
Retrieval of the values (either 1 by 1 or all together in a single operation)
Check for existing credentials
Check for valid credentials and renew them if required

Because the manager receives a Storage, which abstracts the logic of reading/writing stuff, how the values are persisted is up to that implementation. What it's missing is a security layer to encrypt the values before saving them, ask for authentication before retrieving them, or both of the previous.

Secure CredentialsManager (v2)

We can enhance the existing manager to make it encrypt/decrypt the content before persisting it. Then as an extra improvement, we can ask for user authentication before allowing them to obtain the credentials.

APIs

API 18 introduces the algorithm I'm using to encrypt/decrypt.
API 21 introduces the Intent to call the LockScreen and wait for a cancel/pass signal.
API 23 introduces the protected keys, which means that in every key use we can ask for the user to be authenticated first.

The CredentialsManager usage can be divided in two:

	#
	# Build configuration for Circle CI
	#

	machine:
	environment:
	ANDROID_HOME: /usr/local/android-sdk-linux
	GRADLE_OPTS: '-Dorg.gradle.jvmargs="-Xmx2048m -XX:+HeapDumpOnOutOfMemoryError"'
	_JAVA_OPTIONS: "-Xms512m -Xmx1024m"
	ANDROID_API_LEVEL: 25

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