RSA Encryption / Decryption

2048-bit is the minimum recommended key size for RSA. Use 4096-bit for high-security scenarios where long-term data protection is required. Larger keys are more secure but slower to generate and use.

RSA is designed for small data — typically only used to encrypt a symmetric key. For bulk data encryption, use AES. A common hybrid approach is to encrypt your data with AES, then encrypt the AES key with RSA.

No. Keys are generated entirely in your browser and are never stored or transmitted. You must save your private key manually — losing it means losing access to anything encrypted with the corresponding public key.

The public key can be shared with anyone and is used to encrypt data. Only the matching private key can decrypt what was encrypted with the public key. This asymmetric design means you can receive encrypted messages from anyone without ever sharing a secret.

RSA can only encrypt data smaller than its key size (e.g. ~245 bytes for a 2048-bit key with OAEP). For large data, use a hybrid approach: encrypt the data with AES, then use RSA to encrypt only the AES key. This is how TLS/HTTPS works.

Use RSA-OAEP for all new applications — it is the modern secure standard. Avoid PKCS#1 v1.5 padding which is vulnerable to padding oracle attacks (Bleichenbacher attack). Most browsers support RSA-OAEP natively via the Web Crypto API.