~/.ssh/authorized_keys
file, as a new lineFingerprintManager.CryptoObject
is a wrapper around the Java cryptography APIs and is used by the FingerprintManager
to protect the integrity of the authentication request. Typically, a Javax.Crypto.Cipher
object is the mechanism for encrypting the results of the fingerprint scanner. The Cipher
Visual studio 2012 premium product key generator online. Edit generated media key not working in vegas 12 0. object itself will use a key that is created by the application using the Android keystore APIs.CryptoObject
, and then explain in more detail:Cipher
for each CryptoObject
, using a key that was created by the application. The key is identified by the KEY_NAME
variable that was set in the beginning of the CryptoObjectHelper
class. The method GetKey
will try and retrieve the key using the Android Keystore APIs. If the key does not exist, then the method CreateKey
will create a new key for the application.Cipher.GetInstance
, taking a transformation (a string value that tells the cipher how to encrypt and decrypt data). The call to Cipher.Init
will complete the initialization of the cipher by providing a key from the application.Cipher.Init
will throw a KeyPermanentlyInvalidatedException
. The above sample code will trap that exception, delete the key, and then create a new one.CryptoObjectHelper
class uses the Android KeyGenerator
to create a key and store it on the device. The KeyGenerator
class can create the key, but needs some meta-data about the type of key to create. This information is provided by an instance of the KeyGenParameterSpec
class.KeyGenerator
is instantiated using the GetInstance
factory method. The sample code uses the Advanced Encryption Standard (AES) as the encryption algorithm. AES will break the data up into blocks of a fixed size and encrypt each of those blocks.KeyGenParameterSpec
is created using the KeyGenParameterSpec.Builder
. The KeyGenParameterSpec.Builder
wraps the following information about the key that is to be created:BLOCK_MODE
is set to Cipher Block Chaining (KeyProperties.BlockModeCbc
), meaning that each block is XORed with the previous block (creating dependencies between each block).CryptoObjectHelper
uses Public Key Cryptography Standard #7 (PKCS7) to generate the bytes that will pad out the blocks to ensure that they are all of the same size.SetUserAuthenticationRequired(true)
means that user authentication is required before the key can be used.KeyGenParameterSpec
is created, it is used to initialize the KeyGenerator
, which will generate a key and securely store it on the device.CryptoWrapper
into the CryptoObjectHelper
class, let's revisit the code from the start of this guide and use the CryptoObjectHelper
to create the Cipher and start a fingerprint scanner:CryptoObject
, lets move on to see how the FingerprintManager.AuthenticationCallbacks
are used to transfer the results of fingerprint scanner service to an Android application.