RSA (Rivest-Shamir-Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission. It relies on the computational difficulty of factoring large composite numbers.

Key Sizes:

• 1024 bits: Legacy size, no longer recommended for new applications
• 2048 bits: Current standard, suitable for most applications until 2030
• 3072 bits: High security, recommended for sensitive data
• 4096 bits: Maximum security, slower but highly secure

Use Cases:

• Digital Signatures: Verify authenticity and integrity of messages
• Encryption: Secure communication and data protection
• Key Exchange: Securely exchange symmetric keys
• Authentication: Verify identity in various protocols

Security Note: Always use key sizes of at least 2048 bits for new applications. Keep your private key secure and never share it. The public key can be shared freely and is used to encrypt data or verify signatures created with the corresponding private key.