Passage Summary: Because people are starting to lock their digital diaries with passwords, historians won't be able to read them, and biography as we know it will die out.

Conclusion: The widespread use of encryption software will effectively terminate the practice of writing biographical history.

Reasoning: Biographers rely on private papers that will soon be locked behind passwords, making the most essential source material inaccessible.

Analysis: The first sentence is the main point the author wants us to believe, while the rest of the text provides the evidence for why this 'death of biography' is coming. I identified this by looking for the most 'extreme' claim that is supported by the other premises but doesn't support anything else itself. In 'Identify the Conclusion' questions, the conclusion is often at the beginning or middle, rather than the end, so don't let the placement fool you.