cryptoObjectForKeyAgreement

Gets a BiometricPrompt.CryptoObject for ECDH.

This can be used with BiometricPrompt to unlock the key. On successful authentication, this object should be passed to AndroidKeystoreSecureArea.keyAgreement.

Note that a BiometricPrompt.CryptoObject is returned only if the key is configured to require authentication for every use of the key, that is, when the key was created with a zero timeout as per AndroidKeystoreSecureArea.CreateKeySettings.Builder.setUserAuthenticationRequired.