About RSA Key Pair

Use RSA Key Pair to Generate PEM keys. The tool runs in your browser for fast results and keeps your data local.

How to Use

  1. 1. Add your input or data.
  2. 2. Adjust options if needed.
  3. 3. Review the result and copy it.

What is RSA Encryption?

RSA (Rivest-Shamir-Adleman) is an asymmetric cryptographic algorithm that uses a pair of keys: a public key for encryption and a private key for decryption. Unlike symmetric encryption where the same key encrypts and decrypts, RSA allows anyone to encrypt data with the public key, but only the private key holder can decrypt it. RSA is based on the mathematical difficulty of factoring large prime numbers. Common key sizes are 2048, 3072, and 4096 bits—larger keys provide more security but slower performance. RSA is widely used for secure data transmission, digital signatures, SSL/TLS certificates, SSH authentication, and email encryption. The public key can be freely shared, while the private key must be kept secret.

Common Use Cases

RSA is fundamental to modern secure communication and authentication. System administrators use RSA key pairs for SSH authentication to servers without passwords. SSL/TLS certificates use RSA for secure HTTPS connections and website identity verification. Email encryption systems like PGP and S/MIME use RSA to encrypt messages. Code signing uses RSA to verify software authenticity and integrity. VPN connections use RSA for secure key exchange. API authentication systems use RSA signatures to verify request authenticity. Digital signature systems use RSA to prove document authenticity and non-repudiation. Blockchain and cryptocurrency systems use RSA-like algorithms for transaction signing.

  • SSH key-based authentication to servers
  • SSL/TLS certificates for HTTPS websites
  • Email encryption with PGP and S/MIME
  • Code signing for software distribution
  • VPN secure key exchange and authentication
  • API request signing and verification
  • Digital signatures for document authenticity
  • Cryptocurrency transaction signing

Best Practices & Tips

Use at least 2048-bit keys for modern security—1024-bit keys are no longer considered secure. For long-term security, use 4096-bit keys, though they are slower. Generate keys on secure, offline systems when possible. Protect private keys with strong passphrases and restrict file permissions (chmod 600 on Unix). Never share private keys—only distribute public keys. Store private keys in secure locations like hardware security modules (HSMs) for critical systems. Use separate key pairs for different purposes (SSH, code signing, encryption). Rotate keys periodically and revoke compromised keys immediately. Back up private keys securely—losing them means losing access.

  • Use at least 2048-bit keys, 4096-bit for long-term security
  • Generate keys on secure, offline systems when possible
  • Protect private keys with strong passphrases
  • Set strict file permissions (chmod 600) on private keys
  • Never share private keys, only distribute public keys
  • Use separate key pairs for different purposes
  • Rotate keys periodically and revoke compromised keys
  • Back up private keys securely to prevent loss of access

Troubleshooting Common Issues

If SSH authentication fails with "permission denied", check private key file permissions—they must be 600 (readable only by owner). If you see "bad permissions" errors, use chmod 600 on the private key file. If the key format is rejected, convert between formats using tools like ssh-keygen or openssl. Passphrase-protected keys require entering the passphrase—if forgotten, the key cannot be recovered. If public key authentication is not working, verify the public key is correctly added to authorized_keys on the server. Performance issues with large keys can be mitigated by using 2048-bit instead of 4096-bit for non-critical applications. If keys are lost, generate new pairs and update all systems.

  • SSH authentication failing due to incorrect file permissions
  • Bad permissions errors requiring chmod 600
  • Key format incompatibility between different tools
  • Lost passphrase making private key unusable
  • Public key not properly added to authorized_keys
  • Performance issues with 4096-bit keys
  • Lost private keys requiring complete key regeneration

Frequently Asked Questions

Is RSA Key Pair free to use?

Yes. RSA Key Pair is free and works directly in your browser.

Does RSA Key Pair upload my data?

No. Most processing happens locally. Any network requests are clearly indicated.

What formats does RSA Key Pair support?

RSA Key Pair supports the common formats described on the page. Convert uncommon formats before pasting.

How should I share results from RSA Key Pair?

Copy the output and review any sensitive data before sharing or publishing.