Elliptic Curve Cryptography Definition
Elliptic Curve Cryptography (ECC) is a key-based technique for encrypting data. ECC focuses on pairs of public and private keys for decryption and encryption of web traffic.
ECC is frequently discussed in the context of the Rivest–Shamir–Adleman (RSA) cryptographic algorithm. RSA achieves one-way encryption of things like emails, data, and software using prime factorization.
What is Elliptic Curve Cryptography?
ECC, an alternative technique to RSA, is a powerful cryptography approach. It generates security between key pairs for public key encryption by using the mathematics of elliptic curves.
RSA does something similar with prime numbers instead of elliptic curves, but ECC has gradually been growing in popularity recently due to its smaller key size and ability to maintain security. This trend will probably continue as the demand on devices to remain secure increases due to the size of keys growing, drawing on scarce mobile resources. This is why it is so important to understand elliptic curve cryptography in context.
In contrast to RSA, ECC bases its approach to public key cryptographic systems on how elliptic curves are structured algebraically over finite fields. Therefore, ECC creates keys that are more difficult, mathematically, to crack. For this reason, ECC is considered to be the next generation implementation of public key cryptography and more secure than RSA.
It also makes sense to adopt ECC to maintain high levels of both performance and security. That’s because ECC is increasingly in wider use as websites strive for greater online security in customer data and greater mobile optimization, simultaneously. More sites using ECC to secure data means a greater need for this kind of quick guide to elliptic curve cryptography.
An elliptic curve for current ECC purposes is a plane curve over a finite field which is made up of the points satisfying the equation:
y²=x³ + ax + b.
In this elliptic curve cryptography example, any point on the curve can be mirrored over the x-axis and the curve will stay the same. Any non-vertical line will intersect the curve in three places or fewer.
Elliptic Curve Cryptography vs RSA
The difference in size to security yield between RSA and ECC encryption keys is notable. The table below shows the sizes of keys needed to provide the same level of security. In other words, an elliptic curve cryptography key of 384 bit achieves the same level of security as an RSA of 7680 bit.
RSA Key Length (bit)
1024
2048
3072
7680
15360
ECC Key Length (bit)
160
224
256
384
521
There is no linear relationship between the sizes of ECC keys and RSA keys. That is, an RSA key size that is twice as big does not translate into an ECC key size that’s doubled. This compelling difference shows that ECC key generation and signing are substantially quicker than for RSA, and also that ECC uses less memory than does RSA.
Also, unlike in RSA, where both are integers, in ECC the private and public keys are not equally exchangeable. Instead, in ECC the public key is a point on the curve, while the private key is still an integer.
A quick comparison of the advantages and disadvantages of ECC and RSA algorithms looks like this:
ECC features smaller ciphertexts, keys, and signatures, and faster generation of keys and signatures. Its decryption and encryption speeds are moderately fast. ECC enables lower latency than inverse throughout by computing signatures in two stages. ECC features strong protocols for authenticated key exchange and support for the tech is strong.
The main disadvantage of ECC is that it isn’t easy to securely implement. Compared to RSA, which is much simpler on both the verification and encryption sides, ECC is a steeper learning curve and a bit slower for accumulating actionable results.
However, the disadvantages of RSA catch up with you soon. Key generation is slow with RSA, and so is decryption and signing, which aren’t always that easy to implement securely.
Advantages of Elliptic Curve Cryptography
Public-key cryptography works using algorithms that are easy to process in one direction and difficult to process in the reverse direction. For example, RSA relies on the fact that multiplying prime numbers to get a larger number is easy, while factoring huge numbers back to the original primes is much more difficult.
However, to remain secure, RSA needs keys that are 2048 bits or longer. This makes the process slow, and it also means that key size is important.
Size is a serious advantage of elliptic curve cryptography, because it translates into more power for smaller, mobile devices. It’s far simpler and requires less energy to factor than it is to solve for an elliptic curve discrete logarithm, so for two keys of the same size, RSA’s factoring encryption is more vulnerable.
Using ECC, you can achieve the same security level using smaller keys. In a world where mobile devices must do more and more cryptography with less computational power, ECC offers high security with faster, shorter keys compared to RSA.
How Secure is Elliptic Curve Cryptography?
There are several potential vulnerabilities to elliptic curve cryptography, including side-channel attacks and twist-security attacks. Both types aim to invalidate the ECC’s security for private keys.
Side-channel attacks including differential power attacks, fault analysis, simple power attacks, and simple timing attacks, typically result in information leaks. Simple countermeasures exist for all types of side-channel attacks.
An additional type of elliptic curve attack is the twist-security attack or fault attack. Such attacks may include invalid-curve attacks and small-subgroup attacks, and they may result in the private key of the victim leaking out. Twist-security attacks are typically simply mitigated with careful parameter validation and curve choices.
Although there are certain ways to attack ECC, the advantages of elliptic curve cryptography for wireless security mean it remains a more secure option.
What Is an Elliptic Curve Digital Signature?
An Elliptic Curve Digital Signature Algorithm (ECDSA) uses ECC keys to ensure each user is unique and every transaction is secure. Although this kind of digital signing algorithm (DSA) offers a functionally indistinguishable outcome as other DSAs, it uses the smaller keys you’d expect from ECC and therefore is more efficient.
What is Elliptic Curve Cryptography Used For?
ECC is among the most commonly used implementation techniques for digital signatures in cryptocurrencies. Both Bitcoin and Ethereum apply the Elliptic Curve Digital Signature Algorithm (ECDSA) specifically in signing transactions. However, ECC is not used only in cryptocurrencies. It is a standard for encryption that will be used by most web applications going forward due to its shorter key length and efficiency.
What is Elliptic Curve Cryptography Used For?
Avi’s software load balancer offers an elegant ECC solution. Avi fully supports termination of SSL– and TLS-encrypted HTTPS traffic. Avi’s support for SSL/TLS has included support for both RSA and ECC keys without the need for any proprietary hardware. See documentation for Elliptic Curve versus RSA Certificate Priority within Avi.
Read these blog posts to learn more about elliptic curve cryptography:
- Five Excuses for Weak SSL Security
- The Hardware Load Balancer Bubble
- The Million Dollar Question – Do Hardware Load Balancers Scale?
For more on the actual implementation of load balancing, security applications and web application firewalls check out our Application Delivery How-To Videos.