This lesson's interactive features are locked, please to keep using them
RSA vs. ECC
To be clear, RSA is still widely used in production and is still considered secure. Where ECC shines is that it is a bit more efficient in terms of both speed and memory usage. Let's take a look at some of the differences between RSA and ECC.
RSA
RSA key sizes are larger, 2048, 3072, or 4096 bits to remain secure
RSA's security is based on the difficulty of factoring large numbers
RSA is relatively slow. Because of this, it is not commonly used to directly encrypt user data. More often, RSA was used to transmit shared keys for symmetric-key cryptography, as it did in older versions of TLS/HTTPS. Today, TLS mostly uses RSA for signatures on certificates.
ECC
ECC key sizes are smaller, typically 256 bits are enough to remain secure
ECC's security is based on the mathematics of elliptic curves
Comparing Key Sizes
| Security Bits | RSA (bits) | ECC (bits) |
|---|---|---|
| 80 | 1024 | 160 |
| 112 | 2048 | 224 |
| 128 | 3072 | 256 |
| 192 | 7680 | 384 |
| 256 | 15360 | 512 |
To get 2^256 combinations, RSA requires 15360 bits in a private key, while ECC requires only 512 bits. That's a huge difference! You can save a lot of memory and processing power if you're using a lot of keys. That's why systems like Bitcoin use ECC.