Е-пощенска сигурност / E-mail Security

This geocache consists of a lecture, a practical exercise and a homework. You need to solve the homework problem to get the final coordinates.
The container is not close to the initial coordinates. It is located within 100 km by road away from them. The closest train station is less than 10 km away from the cache but using a car is the most convenient approach. We advise you to discover the final coordinates at home and then plan your trip.

The goal of this cache is to teach you about e-mail security - how to send and receive encrypted and signed e-mail messages.

First, read the lecture to learn about the principles of e-mail security.
Then, read the exercise to see how e-mail security is applied using an e-mail client.
And finally, do the following homework:

Mariyka is a bot. She knows the final coordinates of this geocache. You will need to play the role of Ivancho.
The public keys will be exchanged via the cache description - the most authoritative channel possible.

1. Send your public key to Mariyka. There are two ways to do this:
   • Send your public PGP key to the geocache owners - it will be forwarded to Mariyka immediately. Just paste the contents of the public key in the message. Any text is allowed before of after the key - it will be read by Mariyka's human masters. You won't receive any feеdback - neither in the case of success nor in the case of failure, so be careful.
   • Upload your public PGP key to Mariyka's web site. In this case you will get feedback.
2. Get Mariyka's public PGP key. Its ID is: 8FFBD828.
3. Send Mariyka an encrypted and signed e-mail message. Its body (and not the subject) must contain the code of the geocache (OC13031) as a separate word - otherwise she will consider your message to be spam and she will ignore it. Apart from this keyword you may write whatever you wish - Mariyka's human masters will read it.
4. Mariyka will reply to you with the geocache coordinates and a spoiler picture in an encrypted and signed e-mail message.

Warnings:

This geocache has been created with an educational purpose. We hope that by doing the homework you will learn something useful. That is why we, the owners, have a zero tolerance policy against hinting!

• Don't call us for hints - you won't get any. But if you suspect that there is a technical problem with the bot then do report it, please.
• In case you are planning to find the geocache as a team then do the homework as the same team.
• If you give even the slightest hint in your visit log it will be deleted as soon as possible. We will then contact you to tell you what we have considered to be a hint and give you an advise on how to avoid it. If you are worried that your visit log may contain hints you may contact us before posting it.
• We cannot stop you from giving hints using other channels but if we ever find out that you have done so we will be very offended.

Mariyka is a busy bot. Occasionally, she may miss an e-mail message. If you are sure that you have sent her a message that fulfils all of the requirements but you don't receive a reply from her within a couple of minutes then send her a new request and excuse her, please.