If you want to improve the security of your email messages, PGP offers a relatively easy and cost-effective way to do this. In order to understand how PGP works, it’s useful to look at a diagram: PGP shares some features with other encryption systems you may have heard of, like Kerberos encryption (which is used to authenticate network users) and SSL encryption (which is used to secure websites).Īt a basic level, PGP encryption uses a combination of two forms of encryption: symmetric key encryption, and public-key encryption. First, PGP generates a random session key using one of two (main) algorithms.At the highest level, this is how PGP encryption works: The mathematics behind encryption can get pretty complex (though you can take a look at the math if you like), so here we’ll stick to the basic concepts. This key is a huge number that cannot be guessed, and is only used once. This is done using the public key of the intended recipient of the message. The sender sends their encrypted PGP session key to the recipient, and they are able to decrypt it using their private key.The public key is tied to a particular person’s identity, and anyone can use it to send them a message. Using this session key, the recipient is now able to decrypt the actual message. Why would we encrypt the encryption key itself? This might seem like a strange way to do things. Public key cryptography is much, much slower than symmetric encryption (where both the sender and recipient have the same key). Using symmetric encryption requires, though, that a sender share the encryption key with the recipient in plain text, and this would be insecure. So by encrypting the symmetric key using the (asymmetric) public-key system, PGP combines the efficiency of symmetric encryption with the security of public-key cryptography. In practice, sending a message encrypted with PGP is simpler than the above explanation makes it sound. Let’s take a look at ProtonMail – as an example. ProtonMail natively supports PGP, and all you have to do to encrypt your email is to select Sign Mail. The email will look like this (the email addresses have been blurred for privacy reasons): You will see a padlock icon on the subject line of their emails. ProtonMail – like most email clients that offer PGP – hides all of the complexity of the encryption and decryption of the message. Encrypting files stored on your devices or in the cloud.Verifying the identity of the person who has sent you this message.Sending and receiving encrypted emails.There are, essentially, three main uses of PGP: If you are communicating to users outside of ProtonMail, you need to send them your public key first.Īnd so, although the message was sent securely, the recipient does not have to worry about the complexities of how this was done. Of these three uses, the first – sending secure email – is by far the dominant application of PGP. But let’s take a brief look at all three Encrypting EmailsĪs in the example above, most people use PGP to send encrypted emails. In the early years of PGP, it was mainly used by activists, journalists, and other people who deal with sensitive information. The PGP system was originally designed, in fact, by a peace and political activist named Phil Zimmermann, who recently joined Startpage, one of the most popular private search engines. Today, the popularity of PGP has grown significantly. As more users have realized just how much information corporations and their governments are collecting on them, huge numbers of people now use the standard to keep their private information private. Digital Signature VerificationĪ related use of PGP is that it can be used for email verification.
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