Compare RSA - DSA - ECC Encryption Algorithms

Public Key Cryptography uses mathematics to create two keys : a Public Key for encrypting messages and a Private Key for decrypting them. This ensures that only the intended recipient can read a message.

The main algorithms are RSA, DSA and Elliptic Curve Cryptography (ECC), each with its own advantages in performance, speed and security. RSA is the oldest and is known for its strength, while ECC offers strong security with smaller keys, which suits devices with limited processing power.

DSA, which the United States Federal Government supports, is effective for signing and verifying messages, although it is now rarely used for SSL Certificates. These methods underpin the Digital Certificates used for secure web browsing and other forms of digital identity. As quantum computing advances, new post-quantum algorithms are being developed to maintain security in the future.

RSA, DSA and ECC are the main algorithms for creating keys in Public Key Infrastructure (PKI), which manages identity and security in online communications and networking. The technology behind PKI is Public Key Cryptography, which uses two related keys that work together to encrypt and decrypt messages.

This method is called asymmetric encryption, and it differs from symmetric encryption, which uses a single key for both processes. The benefit of asymmetric encryption is that the Public Key can be shared openly while the Private Key remains secure on the user's device, which offers stronger security than symmetric encryption alone. Learn About Private and Public Keys 🔗

Public Key Cryptography and Encryption

Public Key Cryptography uses mathematical algorithms to create its keys. The Public Key is a series of random numbers used to encrypt a message, and only the intended recipient can unlock and read it using a Private Key that is known only to them.

Public Keys are produced with complex algorithms that link them to their Private Keys in order to resist brute force attacks. The size of the Public Key, measured in bits, affects its security.

For example, 2048-bit RSA keys are commonly used in SSL Certificates, digital signatures and other Digital Certificates, which provides enough security to deter attackers. Organizations such as the CA/Browser Forum set minimum standards for key sizes.

Public Key Infrastructure (PKI) supports the Digital Certificates encountered when using websites, mobile apps, online documents and connected devices. One well-known application of PKI is X.509-based Transport Layer Security (TLS) and Secure Sockets Layer (SSL), which forms the foundation of the HTTPS protocol for secure web browsing.

Digital Certificates are also used for application code signing, digital signatures and other aspects of digital identity and security. Learn About Code Signing Certificates 🔗

RSA, DSA and ECC Algorithms

Three main algorithms generate keys in PKI : Rivest-Shamir-Adleman (RSA), the Digital Signature Algorithm (DSA) and Elliptic Curve Cryptography (ECC).

The RSA algorithm, created in 1977 by Ron Rivest, Adi Shamir and Leonard Adleman, relies on the difficulty of factoring large prime numbers. It was the first to implement the Public Key and Private Key system, and its common key length today is 2048 bits. Learn About RSA Encryption 🔗

ECC is based on the mathematics of elliptic curves and offers similar security to RSA and DSA with much shorter keys. It is the newest of the three algorithms.

The Elliptic Curve Digital Signature Algorithm (ECDSA) was recognized in 1999, followed by key agreement and key transport methods using elliptic curves in 2001. Learn About The Elliptic Curve Digital Signature Algorithm 🔗

ECC is certified under the Federal Information Processing Standards (FIPS) and is supported by the National Security Agency (NSA).

DSA uses a different method from RSA to generate Public and Private Keys, relying on modular exponentiation and the discrete logarithm problem. It provides security levels similar to RSA at the same key size. DSA was introduced by the National Institute of Standards and Technology (NIST) in 1991 and became an official standard in 1993.

More than one algorithm can be used together. For example, some web servers can manage both RSA and DSA keys, which improves flexibility. Learn About Choosing the Right Encryption 🔗

ECC Encryption Strength Comparison

The main difference between ECC and RSA or DSA is that ECC provides stronger security for the same key length. An ECC key is more secure than an RSA or DSA key of equal size.

The 521 bit figure in the final row is correct and is not a typographical error. It refers to the P-521 curve, whose field size is 521 bits rather than 512.

ECC achieves similar cryptographic strength with much smaller key sizes. For example, matching the strength of a 112-bit symmetric key requires a 2048-bit RSA key, but only a 224-bit ECC key.

Because the keys are shorter, ECC requires less processing power to encrypt and decrypt data. This makes ECC well suited to mobile devices, the Internet of Things and other applications with limited computing capability. Learn About Elliptic Curve Cryptography 🔗

Reasons ECC Adoption Has Been Slower

RSA remains the most widely used method, partly because it has been available for far longer, although ECC continues to gain recognition. A few factors have slowed wider adoption of ECC.

The first is the learning curve. ECC is harder to understand and implement than RSA, and that added complexity can lead to mistakes that weaken security rather than strengthen it.

The second is exposure to particular attacks. ECC can be vulnerable to side-channel attacks, which may create an opening for brute force attempts, and to twist security attacks, although established techniques exist to defend against both.

Quantum Computing

Quantum computing is set to change encryption significantly. Traditional algorithms such as RSA and ECC will be vulnerable to quantum attacks, which makes the move to new methods important for organizations. Several replacement algorithms are already well advanced.

The National Institute of Standards and Technology (NIST) has finalized three post-quantum standards : ML-KEM for key establishment, ML-DSA for digital signatures and SLH-DSA as a hash-based signature alternative.

A fourth signature standard, FN-DSA, which is based on the FALCON algorithm, remains in draft, and a fifth algorithm, HQC, was selected in 2025 to add further diversity for key establishment. Staying aware of these developments will be important for organizations planning ahead. Learn About Post-Quantum Cryptography 🔗