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RSA

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

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Definition

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

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Why it matters

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

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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.

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Real-world example

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

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Advantages

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

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Limitations

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

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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  • Many believe RSA is still the state-of-the-art encryption, but ECC (Elliptic Curve Cryptography) has largely superseded it.
Canonical knowledge ID: glossary:rsa