I have an old wallet.dat file which was encrypted in October 2012. I don't have the exact passphrase but I have a rough idea. I was wondering if anyone knows how to get the passphrase requirement for this specific version (it would help with my guessing). I looked through the source code for Bitcoin-Qt version 0.7.0 and 0.7.1 but all I was able to find was this

ui->warningLabel->setText(tr("Enter the new passphrase to the wallet.
Please use a passphrase of 10 or more random characters, or eight or more words."));

Which is line 33 of askpassphrasedialog.cpp file. I don't think this is a strict requirement for the passphrase although it helps. I would like to see the code which sets the passphrase requirement if possible. Any help would be greatly appreciated!

p.s. Does anyone know if it is possible to decrypt an old wallet without downloading the entire blockchain?