> From: [email protected] [mailto:discuss- > [email protected]] On Behalf Of Scott Ehrlich > > How safe is a password-protected PDF file sent via email? > > I've never run a sniffer to see what could be learned from doing this.
It varies according to the application that creates / encrypts the pdf. But that's probably not very significant. Most of all, there's basically no way to generate a strong enough password to withstand a brute force attack ... Because if you have some secure channel to securely communicate a 43-char long random alphanumeric string with 256bits of binary degrees of freedom, you would probably just use that channel to send the pdf directly. Later versions of Acrobat support S/MIME keys, which are strong enough. You do a key exchange with some recipient and then encrypt, it'll be pretty secure. But complexity is a bit too high for most people. But I see a lot of VPN's out there, and other stuff, configured by people who just don't care about that. So assuming you're not afraid of a brute force attack... In acrobat 3, they supported 40-bit RC4. Not considered secure today. acrobat 6, 128-bit RC4. Still not secure. acrobat 7, 128-bit AES. Maybe secure today, depending on your needs acrobat 9, 256-bit AES. Generally considered secure today as long as you have a sufficiently strong key (on the order of 256 bits effective entropy) _______________________________________________ Discuss mailing list [email protected] http://lists.blu.org/mailman/listinfo/discuss
