secretKey.kt

private fun getOrCreateSecretKey(keyName: String): SecretKey {
        // If Secretkey was previously created for that keyName, then grab and return it.
        try {
            val keyStore = KeyStore.getInstance(ANDROID_KEYSTORE)
            try {
                keyStore.load(null) // Keystore must be loaded before it can be accessed
                keyStore.getKey(keyName, null)?.let {
                    return it as SecretKey
                }
            } catch (ex: Exception) {
                when (ex) {
                    is CertificateException, is IOException, is NoSuchAlgorithmException -> {
                        Logger.e("CryptographyManager", ex.toString())
                    }
                    is UnrecoverableKeyException -> {
                        Logger.e("CryptographyManager", "User disable unlock screen")
                    }
                    else -> throw ex
                }
            }
        } catch (e: KeyStoreException) {
            throw e
        }
        // if you reach here, then a new SecretKey must be generated for that keyName
        val paramsBuilder = KeyGenParameterSpec.Builder(
            keyName,
            KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT
        )
        paramsBuilder.apply {
            setBlockModes(ENCRYPTION_BLOCK_MODE)
            setEncryptionPaddings(ENCRYPTION_PADDING)
            setKeySize(KEY_SIZE)
            setUserAuthenticationRequired(true)
            setInvalidatedByBiometricEnrollment(true)
        }

        val keyGenParams = paramsBuilder.build()
        try {
            val keyGenerator = KeyGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_AES,
                ANDROID_KEYSTORE
            )
            keyGenerator.init(keyGenParams)
            return keyGenerator.generateKey()
        } catch (e: Exception) {
            throw e
        }
    }