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you're watching InfoSec bites a crash course in information security for journalists we're based at the Center for Investigative Journalism in London and supported by the Logan foundation in this tutorial we show you how to use PGP to encrypt and decrypt text and how to work with PGP signatures this video is provided for information only it cannot replace the advice of a trained security professional if lives or Safety depend on your security please seek the advice of an expert the center for investigative journalism is a pioneer in providing expert information security training services to journalists and journalistic institutions to consult with an expert through the CI J or to arrange a CI J training session contact the address on screen the tutorial you are about to watch is part of a series on PGP which you may wish to watch from the beginning it also requires that you have watched our tutorials on the tales operating system if you haven't seen those tutorials click or tap on the pop-up message to access the playlists so you're up and running with PGP on tales if you follow the last video managing your PGP keys you've generated your own keeper your public key and your secret key and you've also exchanged public keys with your contact you've got their public key and they've got yours you're ready to start using PGP as it was intended encrypted communications in this video we're going to look at how to encrypt a piece of text that can be sent in an email using the public key of your contact we'll also look at how to decrypt a piece of text that was sent to you in an email using your secret key we're also going to look at another of PGP x' uses the ability to sign a piece of text with your secret key so that your contact knows it is from you and the ability to take a piece of text that has been signed by your contact and verify it with their public key first and note on the method we're using tales actually comes with the Thunderbird email program installed by default and with the special enigmail plugin which enables Thunderbird to use PGP this is one method can do PGP entails but it's not the method we're going to show you now and the method we're going to show you you use the browser in this case tor browser to access your email the same way you always do and beside the browser you use the text editor to write your emails all encryption and decryption is done using the PGP applet in the top right-hand corner of the screen this method has several benefits it is much simpler than using Thunderbird and enigmail and requires very little setup it also requires you to manually encrypt and decrypt your messages using this method it is very difficult to accidentally send your emails unencrypted because you can see whether the text is encrypted or not and finally using this method you are not limited to email whereas Thunderbird and enigmail are used specifically to send emails using PGP the simpler method isn't just for email for example using this method you could encrypt a piece of text and then send it over a chat or print it out and send it via physical mail so it's much more versatile and gives you a better understanding of the uses and potential of PGP all you need to start using this method is to open tor browser and log into your email account and then click on the PGP applet and open the text editor set the two windows side by side and you're ready to go first of all type your message in text editor once you're done click and drag your mouse to highlight all of the text you've just written right-click and click copy now click on the PGP applet click sign encrypt clipboard with public keys you will now be shown a choose keys window this is where you choose which public keys you are going to use to encrypt the message all of the public keys in your keyring will be listed here to encrypt a message for a contact simply tick the box beside their key if you're sending an email to several recipients you can tick several boxes at once and the message will be encrypted with all of these keys meaning that all of the recipients can decrypt it with their own secret keys if you use the wrong key or if you forget to use the public key of one of the recipients they will not be able to decrypt the message he will also notice that your own key is listed in general you should make sure the box for your own public key is ticked if you don't after you've sent the message you won't be able to read it yourself but perhaps you would like to send a message that you won't be able to decrypt in the future in this tutorial we're going to take our own key and the key of our other contact now we're going to click OK a confirmation box comes up asking you if you trust these keys if you are sure that the keys are truly owned by your contacts if you are click yes now the encryption has been performed to see it right click in the text editor and click paste a block of encrypted text will be pasted into the window so that you can see that it has been properly encrypted it is now safe to send so compose an email to your contact enter an email address and a suitable subject note that the subject is not encrypted so make sure it doesn't give anything away then paste the encrypted text into the body of the email double-check it is as it should be and click send that's it that's how to send an email encrypted to a public key with PGP decrypting a PGP email is even easier once you've received it open the email and find the block of encrypted text drag your mouse to highlight the entire block from - - - and then right click it and click copy you'll see the PGP applet change to indicate it recognizes that you've copied some encrypted text click on the PGP applet and click decrypt verify clipboard now you will be given a pin entry window asking you for the passphrase of your secret key remember the text in this email has been encrypted using your public key the only way to decrypt it is with the corresponding secret key which only you possess tails needs to access the secret key in order to decrypt the text but in order to do so it needs you to enter your secret keys passphrase first you chose the passphrase when you generated your keeper in the last video so enter that passphrase now and then press Enter Tales will decrypt the message using your secret key and a GPG results window will pop up showing you the decrypted message that's it that's how you decrypt a PGP encrypted message with these two techniques encryption and decryption you and your contact can repeat the process to send each other as many encrypted emails as you want just type a reply in TextEdit and then highlight all of the text copy it and use the PGP applet to encrypt it and then send it via email and when you contact sends you an encrypted email back just copy the text and use the GPG applet to decrypt it so that's almost everything you need to know to handle text with PGP but there's one more thing PGP signatures you see PGP doesn't just do encryption public key cryptography public and secret keys also allow you to do something called signing suppose you send an email to your contact but the email is intercepted and then changed to say something different or suppose someone is sending your contact messages and pretending to be you how do you deal with these situations this is the problem PGP signatures are designed to solve signing is done with the secret key it uses the same mathematical properties that encryption uses but this time you're simply creating a signature of the message the resulting signature cryptographically matches both your public key and that exact message so you can then send the message and the signature to your contact and because they have your public key they're able to check or verify the signature to certify that it was you who wrote the message and if someone was to change even a single letter in the message it would no longer match the signature and the verification would fail so for that reason signing a message is a way of making it tamper proof and also assuring your contact that it was you who wrote it a word of warning though if you sign a message it creates a proof that it was you that wrote it you I wish to do this but you may also wish not to do this for instance even the future you would like to plausibly deny that you wrote the message you may not want to sign it with your PGP key we're going to demonstrate how to sign and verify messages with the PGP applet it requires only a minor addition to the process you've already learned to start with type a message in text editor and then highlight the text right click and click copy now click the PGP applet and follow the same procedure as before sign encrypt clipboard with public keys choose the keys you would like to encrypt a message with as before but this time find the drop down menu next to sign message as the menu will show you a list of your private keys if you've been following this tutorial series you'll only have generated one key pair so far so there should only be one option in here click it now click OK and the procedure will be just like when you encrypt except you will be prompted for your passphrase this time this is because tails needs to use your secret key to create the signature type your passphrase and press enter and the message will now be both signed and encrypted if you paste it into the text editor to inspect it it will look no different to a block of encrypted text the signature is embedded within the block of encrypted text so compose an email paste it in make sure it's right and then send it to your contact when your contact decrypt this message they will also be able to check the signature against your public key and verify that it was indeed you that created this message if they send you an encrypted and signed message back it's even easier to verify it it happens automatically when you decrypt it just follow the same procedure for decrypting open the email and copy the block of encrypted text and then click on the PGP applet and choose decrypt verify clipboard type in the passphrase for your secret key and press Enter now when you are shown the GPG results window the decrypted message will be shown in the top pane but cast your eyes to the bottom pane there you will see information about the signature it will tell you when the signature was made and the ID of the key it was made with and beneath that it will tell you if it checks out if it does it will say good signature the message is verified if it does not check out it will say bad signature there is also sometimes a warning beneath this saying this key is not certified with the trusted signature don't worry too much about this it has to do with the web of trust feature on PGP which is not a feature that we cover in this tutorial it has no bearing on whether the signature is good or bad for the purposes of verification all you need to worry about is whether it says good or bad signature that's it for this tutorial we've seen how to encrypt and sign a message with PGP and how to decrypt and verify a message what PGP isn't just for working with text you can also use PGP to encrypt and sign or to decrypt and verify files in the next and final video in our PGP series we're going to show you how to do all of the same things we've just done but this time with files to watch that video click or tap on the pop-up message and choose it now thanks for watching InfoSec bytes if you found this video useful please share it widely with your colleagues and co-workers to support the center for investigative journalism with a donation please visit TC ij.org forward-slash donate and if you would like to watch our other videos please go to InfoSec bytes org were subscribed to our channel below