RSA Encryption/Decryption
Free online RSA encryption/decryption tool, key pair generation
What is RSA Encryption?
RSA is an asymmetric encryption algorithm that uses a pair of keys: a public key for encryption and a private key for decryption. It is widely used in TLS/SSL, SSH, digital signatures, and secure email. Key sizes of 2048 or 4096 bits are recommended for adequate security.
How to Use This RSA Tool
Generate a key pair by selecting a key size and clicking Generate Keys. Use the public key to encrypt text — anyone with the public key can encrypt. Use the private key to decrypt — only the private key holder can decrypt. All cryptographic operations use the Web Crypto API and run entirely in your browser.
▶What key size should I use?
2048-bit keys are the minimum recommended for general use. 4096-bit keys provide stronger security but are slower. Avoid 1024-bit keys — they are no longer considered secure.
▶Can I share my public key?
Yes, public keys are meant to be shared. Anyone can use your public key to encrypt messages that only you can decrypt with your private key. Never share your private key.
▶Why is RSA slow for large data?
RSA is designed for small amounts of data (limited by key size). In practice, RSA encrypts a symmetric key, which is then used to encrypt the actual data. This hybrid approach combines RSA's security with symmetric encryption's speed.
▶What format are the keys in?
Keys are generated in PEM format (Base64-encoded DER), which is the standard format used by OpenSSL, SSH, and most encryption tools.