End-to-End Encryption (E2EE)

Have you ever used WhatsApp or a similar messaging app?

As a user, you send a text, image, voice, or video message to your contact, and they receive it instantly. But there's a lot more going on in the background to keep your message secure.

It's called end-to-end encryption (E2EE), and it ensures that anyone who intercepts the message during transmission won't be able to read it without the encryption key.

What Is End-to-End Encryption?

When you send a message:

  • The app encrypts the messaging using a unique key. 
  • This encrypted message is then transmitted to the recipient's device through the app's servers.
  • When the recipient receives the message, the app decrypts the message using a matching encryption key.

E2EE reduces the impact of data breaches, prevents attackers from intercepting and deciphering messages during transmission, and ensures that only intended recipients can access and read the contents of a message. If you are managing an app with a chat or messaging feature, you should use E2EE. 

How End-to-End Encryption Works

Understanding how E2EE works will help you make sure your products meet the necessary standards for data encryption and security. E2EE depends on multiple components that work together to secure data at rest and in transit. The components include:

  • A key generation algorithm. The key generation algorithm creates unique cryptographic codes and establishes a secure method for exchanging the encryption keys. Use Azure Key Vault, AWS Key Management Service, or any other FIPS-approved key generation algorithm to generate and exchange encryption keys.
  • An encryption algorithm. The encryption algorithm turns unencrypted data into encrypted data, leaving it unintelligible to unauthorized users. Encryption algorithms usually convert plain text into ciphertext and images, videos, or audio files into a binary format, which is then converted into ciphertext. Use FIPS-compliant algorithms such as SPHINCS+, Falcon, or Kyber.
  • A decryption algorithm. The algorithm used for encryption also helps decrypt the data with the appropriate key so that authorized users can access it.
  • Client-side processing. In end-to-end encryption, the encryption and decryption operations occur on the users' devices rather than on servers or intermediaries. You cannot have E2EE without client-side processing, so make sure you design the whole process accordingly.

Use Cases for End-to-End Encryption

Google has introduced a beta version of E2EE for its Workspace customers. Besides email, other use cases for E2EE include:

  • Messaging and communication platforms. Signal and WhatsApp use E2EE to secure their users' messages.
  • File storage and sharing services. Tresorit and Sync use E2EE to secure all files that are stored and shared on their platforms.
  • Collaboration tools and video conferencing platforms. Zoom and Microsoft Teams use E2EE to secure one-on-one calls and team meetings.

Benefits of End-to-End Encryption

The purpose of E2EE is to secure data from unauthorized users. That results in two major benefits: an added layer of security and a lower risk of third-party surveillance.

An Added Layer of Security

With the help of E2EE, the content of each message remains confidential and inaccessible to intermediaries or service providers. This means that even if data is intercepted during transmission, it remains unreadable to the attackers. In case of a data breach, the data stored on company servers remains encrypted. As long as the attackers do not have access to a decryption key, the data remains unintelligible to them even if they acquire it.

This added layer of security also helps companies build user trust. Eighty-seven percent of people won't do business with a company if they don't trust its security practices. With E2EE, you address that concern.

Back in 2021, WhatsApp was heavily criticized for its new policy of sharing user data with Facebook --- its parent company. WhatsApp clarified that Facebook could neither listen to user calls nor see user messages, thanks to E2EE. This helped the company retain users that it was otherwise going to lose to its competitor, Signal.

Lower Risk of Third-party Surveillance 

In some parts of the world, government/mass surveillance initiatives pose a threat to individual privacy. E2EE prevents unauthorized monitoring and access to user communications by ensuring that only the intended recipients can decrypt and read the messages.

An Online Safety Bill introduced in the UK back in 2021 proposed that messaging companies identify abusive content, whether communicated publicly or privately. WhatsApp, Signal, and other messaging companies took issue with the proposal, as they believed it would be "nullifying the purpose of end-to-end encryption." The bill has not been implemented yet and faces delays, but the whole ordeal goes to show that not even governments, nor the companies that host and facilitate end-to-end encrypted messaging, can access the contents of a message as long as E2EE is in place.     

Challenges with End-to-End Encryption

Watch out for the following challenges before implementing E2EE to your product.

Key Management Complexities 

Key loss is a very real threat in E2EE. You need a robust key management system for the distribution, storage, and revocation of keys if you are dealing with multiple users and devices. If an attacker can get their hands on encryption keys, they can access encrypted data.

Balancing Security and Usability Trade-offs

Strong encryption may increase the computational overhead, leading to slower processing speeds and potentially impacting user experience. You can address this issue with usability testing and user feedback. Also, plan for the additional overhead and invest in scalable, cloud-based infrastructure to achieve higher speeds.

Frequently Asked Questions

Can end-to-end encryption be hacked? Is it secure?

E2EE provides a high level of security, but it is not immune to all vulnerabilities. Weak encryption algorithms or compromised encryption keys can undermine the effectiveness of E2EE. Using FIPS-approved algorithms is a good way to address this issue.

E2EE does not protect against threats such as malware, phishing, or device-level compromises. Regularly updating your software, installing security patches, using strong and unique passwords, and using antivirus and anti-malware software can protect against those threats.

Can E2EE be used for all types of data, including multimedia files?

Yes, E2EE can be applied to various types of data, including text, images, audio, and video files. The encryption process may differ for different data formats, but the underlying principles remain the same. Encryption algorithms break down data into binary format and then turn it into ciphertext, which can only be turned back into its readable form with the help of encryption keys generated by the same algorithms.

Does using E2EE impact the performance of applications or services?

Yes, E2EE can introduce some performance overhead due to the computational complexity of encryption and decryption processes.

Developers can fine-tune encryption parameters and algorithms to strike a balance between security and performance. Product performance can also be improved by using better infrastructure and edge computing.

What is an example of end-to-end encryption?

Proton Mail employs a combination of asymmetric and symmetric encryption algorithms to secure user emails. When a sender composes an email, the content is encrypted using the recipient’s public key, ensuring only the intended recipient can decrypt it. Additionally, Proton Mail uses AES-256 symmetric encryption to encrypt attachments and email headers. The encryption keys are managed using OpenPGP, and Proton Mail has no access to the user’s private keys, further enhancing the security and privacy of the communication.

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