> ## Documentation Index
> Fetch the complete documentation index at: https://docs.theblockchainlibrary.com/llms.txt
> Use this file to discover all available pages before exploring further.

# RSA

> A public-key cryptosystem based on the difficulty of factoring large integers.

# RSA

A public-key cryptosystem based on the difficulty of factoring large integers.

## Definition

A public-key cryptosystem based on the difficulty of factoring large integers.

## Why it matters

Cryptography provides the mathematical foundation for keys, signatures, privacy, integrity, and verification.

## How it works

The algorithm generates two very large prime numbers and multiplies them together to create a modulus. A public exponent is chosen, and a corresponding private exponent is mathematically derived. To encrypt, one uses the public exponent to compute a mathematical operation; to decrypt, the private exponent reverses this operation by exploiting the difficulty of prime factorization.

## Real-world example

RSA is widely used in legacy TLS/SSL certificates and secure email protocols like PGP to establish encrypted connections.

## Advantages

* Well-understood standard
* Provides reliable security
* Foundation of internet encryption

## Limitations

* Large key sizes required
* Computationally slow
* Vulnerable to quantum attacks

## Common misconceptions

* People often assume RSA is used for signing crypto transactions, but it is too slow and bloated for modern blockchain networks.
* Many believe RSA is still the state-of-the-art encryption, but ECC (Elliptic Curve Cryptography) has largely superseded it.

## Related knowledge

* [Hash Function](/generated/v2/glossary/hash-function) — term

***

**Canonical knowledge ID:** `glossary:rsa`