How security important is your Bitcoin Passphrase?

I haven't done my homework that might answer this question for me. But if a Bitcoin Passphrase is important security-wise, maybe we are all being duped about the Bitcoin security strength.

The reason that I say this is, I have found my Passphrase in a Bitcoin program log file, in a place that I didn't make a copy of it. In fact, I found it in two places in this file. Yet, if a hacker happened to hack my computer, and happened to be looking for my Passphrase, he would have no trouble finding it, if he knew Passphrases were being recorded in this log file.

The name of this file on my computer is "log.0000001074." Its location is "C:Documents and SettingsOwnerApplication DataBitcoindatabase" where "Owner" may be different on your particular XP computer. The location may vary slightly on other versions of Windows.

I run Windows XP. My first version of the Bitcoin program was 0.7.0. I upgraded this to 0.7.1, and then directly to version 0.8.1 which I am using now.

Now, when you want to create new Bitcoin addresses, so that you can receive Bitcoins into your wallet, you need your Passphrase to create the addresses with the program. I have never sent any Bitcoins anywhere. Do you need the Passphrase to send Bitcoins to other addreses? If you do, you might easily lose yours to a hacker who can gain access to your computer.

I don't understand any of the programming used in the Bitcoin client. But I have programmed Perl in the past. And I know that there are easy ways to use a Passphrase in a program while keeping it encrypted in the database file so that nobody can simply see the Passphrase. This makes me question whether or not the whole Bitcoin program has been built with a backdoor in it, perhaps intentionally.

I sure would like to see some comments on this, from people who know!

PureTrust