Public Key vs Private Key Cryptography - What’s the Difference?

When it comes to cryptography and protecting your sensitive data, two terms are crucial - public and private keys.

This is because they are used to encrypt and decrypt data.

In this article, we’ll explain what these keys are, what they do and what the difference is between public key vs private key cryptography.

What is Private Key Cryptography?#

In private key cryptography, one key is used to both encrypt and decrypt the data and is then shared between the sender and the recipient.

This key can be a QR code, 64-digit hexadecimal code, 256-character binary code, etc.

The idea is just that it needs to be very long, non-guessable and random (or pseudo-random). The reason for this is that a short and guessable private key can be brute-forced by a determined hacker.

Since the private key is shared, this type of cryptography is also called symmetric.

What is Public Key Cryptography?#

In public key cryptography, there are two keys - private and public. Hence, this type is also called asymmetric.

One key, public, is used to encrypt the data from plain text into cipher text and this key can be freely shared. The other key, private, is used to decrypt the data from ciphertext back into plain text and this one is kept secret and held by the recipient.

Difference Between Public Key vs Private Key Cryptography#

There are a few distinct differences between public key vs private key cryptography.

Public Key CryptographyPrivate Key Cryptography
Used two keys. One (public) to encrypt and the other (private( to decrypt dataUses only one key (private) to both encrypt and decrypt data
One key (public) can be freely shared, while the other (private) needs to be secretly keptThe key is always kept secret
The public key can be shared freely, but the private key is shared only between the sender and recipientThe private key needs to be shared between the sender and recipient only
No danger of key loss since it is held publiclyIf the key is lost, you can lose access to the system
Uses RSA algorithmUses AES algorithm


So which one is better? Private or public key cryptography?

There’s no clear “winner” here since both types offer a different purpose and have different advantages and disadvantages.

In general, private key cryptography is better in situations where you work with large databases and closed systems and where speed over privacy is more important.

On the other hand, public key cryptography works better when sharing data across an open network, like email, which is why it is used in end-to-end encryption.