What is RSA?


Cryptography has been used in civilizations in different formats for thousands of years. From ancient Egyptians to the modern Internet, the use of cryptography to encrypt and decrypt messages is an important tool in communication.

The RSA cryptography or RSA algorithm is the most ubiquitous asymmetric encryption algorithm in the world to be precise. Made possible by a series of cryptographic and mathematical advances, anyone who uses the Internet is using RSA cryptography in one way or another.

Most cryptocurrencies employ a type of asymmetric encryption similar to RSA, known as elliptic curve cryptography. Although they are different, both are based on similar concepts and the understanding of RSA is important to advance the understanding of the cryptography used in cryptocurrency networks.

Where is RSA encryption used?

RSA encryption is often used in conjunction with other encryption schemes or for digital signatures that can prove the authenticity and integrity of a message. It is generally not used to encrypt messages or entire files, because it is less efficient and requires more resources than symmetric key encryption.

To make things more efficient, a file will usually be encrypted with a symmetric key algorithm, and then the symmetric key will be encrypted with RSA encryption. Under this process, only an entity that has access to the RSA private key can decrypt the symmetric key.

Without being able to access the symmetric key, the original file cannot be decrypted. This method can be used to keep messages and files safe, without delaying too much or consuming too many computing resources.

RSA encryption can be used in several different systems. It can be implemented in OpenSSL, wolfCrypt, cryptlib and several other cryptographic libraries.

As one of the first widely used public key encryption schemes, RSA laid the foundation for many of our secure communications. It was traditionally used in TLS and was also the basic algorithm used in PGP encryption. RSA is still seen in various web browsers, email, VPN, chat and other communication channels. RSA is also often used to create secure connections between a VPN client and a VPN server. Under protocols such as OpenVPN, TLS handshakes can use the RSA algorithm to exchange keys and establish a secure channel.


RSA encryption is the most commonly used asymmetric encryption method in the world because of its capacity to deliver a high level of encryption without a known algorithm to solve it. Based on some brilliant advances in cryptography and mathematics, including the Diffie-Hellman key exchange and trapdoor function, RSA encryption has become paramount to ensure worldwide communication.