ECDSA vs RSA: Everything You Need to Know


If you’re into SSL certificates or cryptocurrencies, you’d eventually come across the much-talked “ECDSA vs RSA” subject (or RSA vs ECC). What do all of these words mean, and why do they even matter?

Two of the world’s most commonly adopted asymmetric algorithms are ECDSA and RSA. However, when it comes to the way they work and how their keys are created, all these algorithms are drastically different. We will decode all of these encryption algorithms in this article to help you understand what they are, how they work, and to discover their special benefits (and disadvantages). Let’s start now!

RSA Algorithm: What It Is and How It Works

There is no match for the RSA (Rivest Shamir Adleman) asymmetric encryption algorithm when it comes to popularity. When it comes to SSL/TLS licenses, bitcoins, email encryption, and a number of other uses, this algorithm is used commonly.

Since it was invented in 1977 by Ron Rivest, Adi Shamir and Leonard Adleman, when it comes to asymmetric encryption algorithms, RSA has become the gold standard. For one-way encryption of a message, RSA uses the prime factorization form. Two titanic-sized random prime numbers are taken in this process, and they are multiplied to generate another gigantic number.

The multiplication of these two numbers is simple, but it is almost a difficult task to calculate the original prime numbers from this multiplied number, at least for modern supercomputers. The “prime factorization” method is called this operation. It is an awfully difficult job to figure out the two prime numbers in the RSA algorithm, which took a group of researchers more than 1,500 years of computational time (distributed through hundreds of computers) to be able to do so.

ECDSA vs RSA: What Makes RSA a Good Choice

Considering that this one algorithm has been the business experts’ leading option for nearly three decades, you have to respect its durability. In 1994, RSA was first standardized, and it remains the most commonly used algorithm to date. The explanation why it is very important to mention this durability is that it indicates that RSA has stood the test of time. Compared to current algorithms such as ECDSA, it’s an incredibly well-studied and audited algorithm.

The flexibility that it provides is another big element that sets RSA apart from other algorithms. It is based on a basic mathematical approach and is simple to incorporate in the public key infrastructure (PKI). This has been one of the core reasons why the most common encryption algorithm technique remains RSA.

ECDSA Algorithm: What It Is and How It Works

The successor of the digital signature algorithm is the ECDSA (elliptic curve digital signature algorithm), or ECC (elliptic curve cryptography), as it is often called (DSA). ECDSA was born when the use of elliptical curves in cryptography was suggested by two mathematicians named Neal Koblitz and Victor S. Miller. The ECDSA algorithm, though, has taken almost two decades to become standardized.

ECDSA is an algorithm in asymmetric cryptography based on elliptical curves and an underlying function known as a “trapdoor function.” An elliptic curve is the set of points (y2 = x3 + ax + b) that satisfy a mathematical equation. This is how the elliptical curve looks:

ECDSA vs RSA: What makes ECC a better choice

As all asymmetric algorithms go, ECDSA functions in a way that is easy to quantify in one direction, but hard to reverse. In the ECDSA case, the number on the curve is multiplied by another number and, thus, the point on the curve is generated. It is difficult to find out the latest point, even though you know the original point.

Thanks to its sophistication, ECDSA was found to be more safe against existing cracking methods compared to RSA. ECDSA delivers the same degree of protection as RSA, but by using much shorter key lengths, it does so. Therefore, ECDSA would take slightly more time for longer keys to break by brute-forcing attacks.

The value of performance and scalability is another great advantage that ECDSA provides over RSA. Because ECC ensures maximum protection with shorter key lengths, network and processing capacity demand a lower load. For computers that have minimal storage and processing power, this proves to be perfect. The ECC algorithm reduces the time taken to execute SSL/TLS handshakes in SSL/TLS certificates which can help you load your website faster.

The catch, though, is that not all CAs in their control panels and hardware protection modules support ECC (although the number of CAs that do is growing).

ECDSA vs RSA: The Difference of Key Lengths

As we discussed, ECC requires much shorter key lengths to give the same level of security provided by long keys of RSA. Here’s what the comparison of ECDSA vs RSA looks like:

Security (In Bits)RSA Key Length Required (In Bits)ECC Key Length Required (In Bits)

ECC vs RSA: The Quantum Computing Threat

Irreversibility is the key trait that makes an encryption algorithm secure. Therefore, you must perform brute-force attacks, trial and mistake, in plain terms, to break some such algorithm. Due to the encryption key lengths, though, the potential variations that you have to try are in quantities that we can’t even begin to conceptualize correctly.

However, much of this will change in the future with the eventual (and likely) advent of quantum computers. The National Institute of Standards and Technology (NIST) predicts that current public key cryptography will collapse until quantum computation becomes popular. About why? Since quantum computers are mightily efficient since they run on qubits rather than bits, significantly more power than supercomputers today. What this implies is that at any given moment in time, they can attempt several combinations and, thus, their computing time is considerably shorter. These quantum computers, like RSA and ECDSA, are expected to make today’s encryption schemes redundant.

RSA and ECDSA are also potentially susceptible to an algorithm known as Shor’s algorithm, according to different reports. As used for quantum computers, this algorithm is likely to crack both RSA and ECDSA. It has been found that ECDSA is easier to solve compared to the RSA cryptosystem, according to research performed by Microsoft. However, since functional quantum computers are still in their infancy, there’s no reason to think about this right now.

RSA vs. ECDSA: Summary

Till now I hope I’ve been able to clear up any confusion you may have regarding the topic of ECDSA vs RSA. Here’s a summary of all the differences that makes it easy for you to understand:

One of the earliest methods of public-key cryptography, standardized in 1995.Comparatively new public-key cryptography method compared to RSA, standardized in 2005.
Today, it’s the most widely used asymmetric encryption algorithm.Compared to RSA, ECDSA is a less adopted encryption algorithm.
It works on the principle of the Prime Factorization method.It works on the mathematical representation of Elliptical Curves.
RSA is a simple asymmetric encryption algorithm, thanks to the prime factorization method.The complexity of elliptical curves makes ECDSA a more complex method compared to RSA.
RSA is a simpler method to implement than ECDSA.Implementing ECDSA is more complicated than RSA.
RSA requires longer keys to provide a safe level of encryption protection.Compared to RSA, ECDSA requires much shorter keys to provide the same level of security
As it requires longer keys, RSA slows down the performance.Thanks to its shorter key lengths, ECDSA offers much better performance compared to RSA.

Final Word: ECDSA vs RSA

RSA and ECDSA remain two of the most common asymmetric encryption algorithms, no matter their particular advantages and drawbacks. Both of these algorithms have the degree of security that hackers today can’t even dream of reaching. In certain ways, however, both are very distinct. These are the grounds from which they vary, to rehash what we have just learned:

  • Performance
  • Required key length for secure encryption
  • Working principle
  • Scaleability
  • Complexity

The key to these algorithms’ performance and strength lies in their proper execution. If it is poorly applied and meets industry norms, no encryption algorithm can provide optimal security.

There is not much of an argument in the “ECDSA vs. RSA” controversy as far as existing safety requirements are concerned, as you can pick one of them and they are both absolutely safe. I would like to stress the fact that the ECC is not supported as generally as RSA. That being said, the ECC is a safer choice if you have the option to choose.

Melina Richardson
Melina Richardson is a Cyber Security Enthusiast, Security Blogger, Technical Editor, Certified Ethical Hacker, Author at Cybers Guards. Previously, he worked as a security news reporter.