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What is End-to-End Encryption? How It Works, and Why We Need It

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21st Sep, 2022
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What is End-to-End Encryption? How It Works, and Why We Need It

Since data is one of the most valuable resources in today’s digital age, every business must prioritize data protection and security. Moreover, with cybercrime at an all-time high, protecting data and IT infrastructure from malicious intent has become paramount. 

Data encryption in cyber security is fundamental to ensure no malicious parties gain access to sensitive information. It involves converting standard text into unreadable formats (encryption) so only authorized users can read it. A critical line of defense in cybersecurity architecture, data encryption is widely used by large organizations and individual users to protect information exchanged between a browser and server. Whether personal information like credit card transaction details or classified government intelligence, encryption mechanism applies to almost every data protection need.

This article will explore the concept of end-to-end encryption, how it works, and why we need it for secure and private communication. 

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What is end-to-end encryption?

End-to-end encryption is a secure communication method that prevents unauthorized third parties from accessing data while transferring it from one device or system to another. In end-to-end encryption, the data on the sender’s system or device is encrypted or transformed into an unreadable format that only the intended receiver can decipher or decrypt. The process involves using encryption keys to scramble data, ensuring that only authorized parties can decode and read it. Thus, any third party cannot intercept the encrypted data, including hackers, application service providers, and internet service providers while in transit. 

How does end-to-end encryption work?

End-to-end encryption works on the asymmetric or public-key cryptography principle involving a public-private key pair. 

In encryption technology, keys are random bits for encrypting and decrypting data. The public key encrypts data, is widely shared, and is accessible to all, whereas the private key is only available with the authorized receiver and is used to decrypt data. In public-key cryptography, each public key has its corresponding unique private key, and together they are used to encrypt and decrypt messages. So, if you encrypt a message using a person’s public key, only they can decrypt it using the matching private key.

End-to-end encryption is the gold standard for securing communication, with encryption occurring at the device level. In other words, encryption of messages and files occurs before they leave a system or device and are not decrypted until they reach the authorized destination. As a result, hackers and other unwanted third parties cannot access data on the server since they do not have the private key to decode the data. However, only authorized individuals have the secret or private key stored on their device, which allows them to access the data.

An Example of End-to-End Encryption

Now, let’s try and understand the concept of end-to-end encryption with the help of a simple example. 

Suppose Bob wants to send Chris an end-to-end encrypted email. The end-to-end encryption system provides each party with a public-private key pair. While the public keys are stored on the server, the private keys are held on their respective devices. 

Now, Bob will use Chris’s public key to encrypt the email, and when Chris receives the email, they will use the private key on their device to decrypt the message from Bob. Likewise, if Chris wants to reply to the email, they will encrypt their message to Bob using Bob’s public key. 

How is end-to-end encryption different from encryption-in-transit?

Encryption-in-transit is another data encryption technology. It begins with data encryption at the sender’s end, which is then delivered to the server, followed by decryption and re-encryption before being delivered to the receiver. Finally, the data is decrypted on the receiver’s end. Although encryption-in-transit protects data during the transmission, it allows the server to intercept the content. This means encryption-in-transit is a server-side encryption method only for unauthorized third parties.  

On the contrary, end-to-end encryption ensures that only parties with the decryption key can view and process the data. Therefore, only the legitimate receivers can access the data while unintended links and third parties are restricted from reading or modifying the content. 

Why do we need end-to-end encryption?

The main reason why end-to-end encryption is necessary is that it provides users security of their messages and files from when the data leaves the sender’s device/system until the intended recipient receives it. In addition, encryption on either end ensures that no third party can intercept the data while in transit. 

Overall, end-to-end encryption protects users’ data against the following threats:

  • Snooping third parties:

    Since only the authorized sender and receiver have the keys to decrypt end-to-end encrypted messages, the system ensures that no third party has access to the transmitted data. 

  • Data tampering:

    End-to-end encryption protects encrypted messages from being altered while in transit. Any meddling attempt would be apparent since there is no way an encrypted message can be changed.

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Advantages of End-to-End Encryption

The benefits of end-to-end encryption technology include:

Data security in transit

In transit, data protection and data security are the primary advantages of end-to-end encryption. The technology uses public-key cryptography so that only the endpoint devices have private keys. Since only the private keys can decrypt data, only the parties with access to the endpoint devices can read messages.

Protection from data meddling

If encrypted messages are tampered with while in transit, the recipient cannot decrypt them. However, the decryption keys are with the authorized recipients in end-to-end encryption. So, there is no scope for data tampering or alteration in transit. 

Regulatory compliance

Most organizations are bound by data security compliance. It refers to the regulations and standards governing government organizations and companies keeping data private, secure, and safe from threats and breaches. Such compliance measures often mandate encryption-level data security.

Challenges with End-to-End Encryption

End-to-end encryption technology is a crucial component of modern data security measures. However, it too has its limitations.

The challenges with using end-to-end encryption technology include:

Unprotected metadata

Although end-to-end encryption hides the content of the exchanged information, it does not protect the metadata, such as the parties in the exchange or the date and time of transfer. The metadata can give malicious third parties enough clues about where they can intercept the data once decrypted.

Compromised endpoints

Since the technology only protects data between the endpoints, it does not address the issue that the endpoints can be compromised and vulnerable to threats. Therefore, it is pertinent that organizations implement endpoint security to ensure data protection beyond transit.

Man-in-the-middle attacks

MitM or man-in-the-middle attacks involve hackers inserting themselves between two endpoints, eavesdropping, and intercepting messages. They do so by impersonating one of the parties, making it appear as if the usual information exchange is underway. The typical goals of MitM attacks are to steal login credentials, personal information, credit card numbers, illicit password changes, etc.


End-to-end encryption has obvious benefits over traditional clear text messages, where data exchanges occur without any encryption. It is also preferable to encryption-in-transit, where the messages are decrypted and re-encrypted at the intermediate server, which, in turn, serves as a vulnerable point. But despite its advantages, end-to-end encryption has its limitations, such as endpoint vulnerabilities, MtiM attacks, exposed metadata. Yet, the technology remains a security benchmark for organizations worldwide, with prominent apps like WhatsApp, Telegram, and Facebook Messenger offering the end-to-end encryption feature by default. 

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Pavan Vadapalli

Blog Author
Director of Engineering @ upGrad. Motivated to leverage technology to solve problems. Seasoned leader for startups and fast moving orgs. Working on solving problems of scale and long term technology strategy.
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Frequently Asked Questions (FAQs)

1 What does end-to-end encryption mean?

End-to-end encryption means data encryption occurs on the sender’s device or system, and only the intended receiver can decrypt it. It offers a secure mode of communication preventing unauthorized access to data in transit.

2What are end-to-end encrypted messages?

End-to-end encrypted messages mean that all texts and media files are encrypted as they travel between devices or systems. Encryption transforms data into an unreadable format that the intended recipient can decode only with a secret key.

3Can encryption be hacked?

While end-to-end encryption has a prominent role in ensuring secure communication, it does not address the risks and vulnerabilities at the endpoints. Hacking endpoint devices exposes encryption keys to theft. Moreover, MtiM attacks enable hackers to impersonate one of the communicating parties and intercept messages while remaining undetected.

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