The decrypt key is itself encrypted. Admittedly the weak point is the passphrase used by the recipient to decrypt this, but as this never needs communicating to anybody then this is a rather more secure system than a shared passphrase.

Ah sorry I misunderstood, so you still need a password/phrase to decrypt the files once you receive them, but that password/phrase is for your PGP key rather than for the file itself? i.e. if you intercepted the files you would also need BOTH the recipients key, and their password/phrase to get anywhere?

Exactly.

Thunderbird + Enigmail is an easy-to-use pgp (or do I mean gpg?) implementation. Or you can look at x509 certificates to use with Oulook etc.

Hi, what exactly are these Or you can look at x509 certificates to use with Oulook etc if I may?

Is it possible to send encrypted data from my end and not have to have any specialist software on the receivers end, but just a key / code of some sort?

Thanks as always - Blue

GIYF!

http://en.wikipedia.org/wiki/X.509

I haven't used these for a while, but IIRC, Outlook and OE have the ability to use these ready built-in. The recipient needs to have a key pair, and you use his public key to encrypt the email. He deciphers it (automatically, in Outlook) using his private key.

At the time I was playing with these, you could get these keys free from Thawte (since acquired by Verisign), amongst others. I've switched to the thunderbird/enigmail combination as I don't like MS's email products.

PGP/GPG is similar, and open-source, but you generally need an add-on to use it, which may deter some users.

Most of these certificate systems support a "web of trust" scheme, whereby users meet and vouch for each other and therefore you can be reasonably certain that an encrypted or signed message has genuinely come from who it says it has. This is probably not a great concern to you, as you already know who your correspondent will be.

Thanks for all your help and guidance, and the other posters as well.

Blue

Yepp,

Have a look at Comodo at www.instantssl.com for a free certificate to allow you to digitally sign and encrypt mails.

Trusted certificates for free there.