FileEncryptionDemoViewModel.kt

fun readFromEncryptedFile(): String {
    //We will read up to the first 32KB from this file. If your file may be larger, then you
    //can increase this value, or read it in chunks.
    val fileContent = ByteArray(32000)

    //The number of bytes actually read from the file.
    val numBytesRead: Int

    //Open the file for reading, and read all the contents.
    //Note how Kotlin's 'use' function correctly closes the resource after we've finished,
    //regardless of whether or not an exception was thrown.
    encryptedFile.openFileInput().use {
        numBytesRead = it.read(fileContent)
    }

    return String(fileContent, 0, numBytesRead)
}