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Public vs Private Key Encryption

Apr 4, 2024

What Is a Public Key Encryption?

Public key encryption is the way of encryption using two different keys to encode and decode the information. The key used for encoding the data is called a “public key” while the key used to decode the data is a “private key.” Another name of this encryption method is asymmetric encryption. The name derives from the fact that encrypting and decrypting in public key encryption requires different keys.

Image source: GeeksforGeeks

The public key can be shared publicly (hence, the name) because even if this key is obtained by hackers they won’t be able to read the data using this key. All they can do is to encrypt anything else. To decode the information protected via the asymmetric encryption one must use a corresponding private key, and that’s the only way to do that. If this key is nowhere to be found, the data cannot be decrypted.

The vivid example of the difference between public and private keys is the use of them in cryptocurrencies. For instance, the Bitcoin wallet owners keep two keys—a public one and a private one. The public key serves as a wallet address. You can share it online to ask for donations or share it with a person who is going to send you money. It’s safe. What you don’t share with others is the private key because this key is used to sign transactions associated with your wallet (with the corresponding public key). As soon as your private key is stolen, thieves can easily transfer your BTC to another address (if they know your public key). Keeping your private key away from others is a basic rule of cyber security.

Public key encryption is a popular tool in cybersecurity and is in high demand among developers of the apps that require the circulation of sensitive data between counterparts whether it is a web browser and the site or the privacy-focused email agents. Also asymmetric encryption is often used in the digital signature services whereas the private key works as the signature of the signing party.

How Does Public Key Encryption Work?

To use a public key encryption, one generates a pair of keys via one of various cryptographic algorithms (e.g., the Bitcoin network uses the SHA256 algorithm).

When you communicate with others using asymmetric encryption, you turn your data input into a hash (a string of randomly looking fix-sized characters) via a public key while your counterpart decrypts this data using a private key to turn the output into human-readable information or trigger the particular action.

What Is a Private Key Encryption?

Private key encryption uses only one key which is used for encryption and decryption of the information. The message can be decrypted with the same key that was used to encrypt it. The communicating parts should take care of sharing this key with each other to be able to communicate using an encrypted channel. As the same key is used on both ends of communication, the private key encryption is also called a symmetric encryption.

Image source: GeeksforGeeks

Using the same key for encoding and decoding the data makes the communication faster while creating a point of vulnerability in the moment when the involved parties share this key using the unprotected channel. This issue is usually addressed via using a channel protected via asymmetric encryption while exchanging the private key between the parties. Some encryption algorithms combine the elements of symmetric and asymmetric encryption to increase security. Some of these algorithms gained wide recognition. Pretty Good Privacy (PGP) and Secure Sockets Layer (SSL) are among them.

Symmetric encryption is widely used in the work of VPN services. The other notable use case are the messenger apps with end-to-end encryption including WhatsApp and Signal. The private key encryption-based encoding algorithm called Advanced Encryption Standard (AES) is used by the US government to keep secret information. So if you have doubts about the efficiency of this tool, you should think again.

How Does Private Key Encryption Work?

To use a private key encryption one should generate the key and safely share it with the other participant of communication. Then, they can use the key to encrypt the data and exchange it in the encoded form using the Internet or another communication channel. The received encoded information is decrypted via the same secret key.

Public vs Private Key Encryption

Both types of encryption have certain advantages over each other so we can’t blatantly state that one of them is utterly better than the other. Everything depends on the specific case in which one of the encryption types is going to be used.

Asymmetric encryption provides superior protection if compared to symmetric one. Even if one of the keys is stolen, hackers won’t be able to access the private info until they get the second key. The data protected with a single key is more vulnerable as accessing this key is enough to breach the security. More than that, while using asymmetric encryption, parties don’t have to share the key, making the communication easier.

More than that, asymmetric encryption allows a better control over the list of parties who have access to the private data as even only one party of the communication has the private key.

Another advantage of public key encryption is that it can be successfully scaled for large collectives of users without compromizing the safety of data. It makes asymmetric encryption a natural choice for big institutions.

One more strong quality of public key encryption is on-repudiation, meaning that the party sending a message cannot deny the fact of sending this message. This feature can play an important role in the event of a court dispute.

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As for the advantages of private key encryption over the public key encryption, the latter type provides a faster and smoother communication than asymmetric encryption. The reason is clear: as the symmetric encryption uses a single key it requires less computational power. It makes it a better choice for real-time encryption. For instance, symmetric encryption is the first choice for the live streaming apps and any real-time data transmission in general.

Conclusion

Private key encryption provides a faster data transmission due to computational efficiency. However, public key encryption is superior in terms of security as it doesn’t allow you to decode the data using the key that was used to encode it. It bears the potential for a higher scalability allowing to maintain the data privacy and permitted access in huge institutions.

Nevertheless, both types of encryption provide strong protection of data. The biggest applications, the governmental institutions, corporations – they all rely on private key and public key encryption-based solutions.

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