RSA Encrypt Decrypt — Free Online RSA Encryption & Decryption Tool

RSA is the foundation of modern public-key cryptography. Unlike symmetric encryption (where the same key encrypts and decrypts), RSA uses a mathematically linked key pair. Your public key can be freely shared — anyone can use it to encrypt messages that only your private key can decrypt. This solves the key distribution problem that plagued symmetric systems.

This tool uses RSA-OAEP with SHA-256 — the modern, recommended approach to RSA encryption. OAEP padding adds randomness to each encryption operation, meaning the same plaintext produces different ciphertext each time, preventing pattern analysis attacks. The Web Crypto API implementation is native to your browser, requiring no external libraries.

Important: RSA is only suitable for small amounts of data. For large files, use hybrid encryption — encrypt the file with AES, then encrypt the AES key with RSA. This is exactly how TLS, PGP, and most secure protocols work in practice.