End-to-End Encryption Explained

End-to-end encryption protects the privacy and security of communications over the internet. The use of end-to-end encryption can be essential for regulatory compliance (and especially cloud compliance) and protecting personal and sensitive information against cyber threats. 

What is End-to-End Encryption?

End-to-end encryption is designed to protect communications against eavesdropping. The sender of a message encrypts the message with a key known only to the authorized recipients of the message. This data can then be safely sent out over untrusted networks (such as the public internet) without the risk of unauthorized users reading or modifying the message. At the other end, the recipient uses the decryption key to restore the original message.

End-to-end encryption is designed to protect against unauthorized eavesdropping on messages by parties without access to the decryption key. If an attacker can view a message before encryption or after decryption or steals the keys used to protect a message, then they can read and potentially modify it.

The value of end-to-end encryption to an organization lies in its ability to protect data in transit. As remote work, remote sites, and cloud computing become more common, sensitive data increasingly flows over the public internet. While end-to-end encryption can’t help if a remote device is compromised, it can protect against eavesdroppers.

What are Public and Private Keys?

End-to-end encryption systems use a few different types of cryptography. Symmetric cryptography (which uses the same key for encryption and decryption) is fairly straightforward, but asymmetric cryptography (also known as public key cryptography) is a bit more complex.

In public key cryptography, a user has a pair of related keys. A private key is a random number, while the public key is derived from the private key. The relationship between these two keys is that, for a certain algorithm, one undoes what the other does.

Public keys are used to encrypt data and are designed to be common knowledge. Anyone with a user’s public key can send them an encrypted message. At the other end, the private key is used to decrypt that message. Since only the user knows their private key, the message can only be read by its intended recipient.

In end-to-end encryption, public key cryptography can be used to create a shared symmetric encryption key between two parties. Symmetric encryption is more efficient than asymmetric cryptography, but it requires a secret key to be shared over a secure channel to work. 

With public key cryptography, this secret key can be generated and shared in a way that only the authorized recipients of a message can access the key and use it to decrypt the message encrypted with symmetric cryptography.

How Does End-to-End Encryption Work?

End-to-end encryption is performed on the devices of the sender and recipient of a message. Messages are encrypted before they are sent and decrypted on the recipient’s device.

The encryption algorithm used determines the flow of the end-to-end encryption process. If asymmetric encryption is used for all communications, then each message is encrypted with the recipient’s public key and decrypted with their private key. In this case, messages flowing in different directions (i.e. Alice to Bob vs. Bob to Alice) will use different sets of keys.

If symmetric encryption is used to protect the contents of the messages, then the same key will be used for data flowing in both directions. In this case, it is likely that public key cryptography will be used for the initial key exchange.

End-to-end Encryption Explained: Example

When you visit a website, your traffic should be end-to-end encrypted when flowing from your computer to the webserver that stores the desired webpage. This is the case if you are visiting a site using HTTPS, which uses the Transport Layer Security (TLS) protocol for encryption.

TLS uses asymmetric cryptography to set up a shared secret key and symmetric encryption for bulk data encryption. As part of the TLS handshake, the client and the server agree on the algorithms to use and any necessary parameters. This handshake also establishes the shared secret key using asymmetric cryptography.

With this key in hand, the client and server can begin the process of accessing the desired webpage. The client will encrypt their HTTP request with the shared key and send it to the server, which decrypts it using the same key. The server then generates the response, encrypts it, and sends it back to the client.

TLS is an effective end-to-end encryption protocol, but it is important to consider who the intended recipients of a message are and who has access to the keys. A TLS connection to a webserver is end-to-end encrypted because the client and server are the communicating parties and the only ones with access to the encrypted keys.

In contrast, a message sent via a communications platform that uses TLS for data security is not end-to-end encrypted. The server will establish separate TLS connections with the message sender and the message recipient, and the message will be unencrypted on the server. In this case, someone other than the message sender and intended recipients (i.e. the server) has access to the decryption keys and can read the message. This is not end-to-end encryption.

Taking Advantage of the Benefits of End-to-End Encryption

So what is end-to-end encryption? In the end, it is an invaluable tool for data security and regulatory compliance. This is especially true as remote work and cloud-based data storage and sharing become more common and a growing vector for data breaches. Being able to explain end-to-end encryption is vital for gaining the support needed within your organization to build out your cybersecurity infrastructure. 

Hyper Vigilance’s GuardNet offers turnkey end-to-end encryption support for an organization’s emails and files. Learn more about how to use GuardNet to support your regulatory compliance efforts, or contact us for more information today.