I have taken a look at the above product as recommend in the blog. But I'm struggling to understand how it works. From what I have read each person downloads the exchange software then emails the other person the tex in the first box. So each person as two box's one containing info pre-set and the next box down the others persons pre-set info. Both press calculate and a shared key is calculated. But if a party was to know what each persons first box of tex is surely they could also work out the key ?? as both people need to send the first part of the pre-set info to the other party.

Hope this makes sense to someone >????

I don't think your analysis is right. Say you and I exchange keys. You have a specific first text and I have a specific first text. We exchange. A unique secret key is generated that is based on both public keys. If a third party were to intercept both our first keys, which is possible, when he calculates his exchanged key, he ends up with a different unique key than our key.

For example:

First Key:

Second First Key:

Input both of these in the same order a few times and each time a new unique secret key is generated. This means that the eavesdropper will only be able to generate a different secret key than the one we generated.

However, I also could be wrong. If there is more than one single secret key generated for the same public keys between our public key exchange, then I suppose someone else could use a third party key exchange as well.

It is best to test it. If you like, send me a PM (private message) and we can exchange public keys and see what private key(s) we generate.

Hmm I'm still struggling to see how this works also, as we both must send each other the tex from the first box. If a second party see's the tex we exchange surely they also will be able to use the key exchange and work out the key ???

PM sent - thank you !!!