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RSA Encrypt and Decrypt

Generate an RSA-OAEP key pair, export and import PEM keys, and encrypt short text.

RSA encrypt and decrypt

Generate a key pair to begin.
Decrypted text will appear here.
A 2048-bit RSA-OAEP key with SHA-256 can encrypt only about 190 bytes, because the padding and hash need part of the space.

How to use the RSA Encrypt and Decrypt

  1. Generate a key pair, or paste an existing pair in PEM form and import it.
  2. Type a short message and click Encrypt to get the ciphertext in base64.
  3. Paste ciphertext back in and click Decrypt to read the original message.

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Frequently Asked Questions

Common questions about the free online rsa encrypt and decrypt.

RSA is a public key cipher. Anyone can encrypt a message with your public key, but only the matching private key can turn it back into readable text.
RSA-OAEP with a 2048-bit key and SHA-256 can encrypt about 190 bytes at most, because the padding and the hash take up part of the space.
Encrypt a random symmetric key with RSA, then encrypt the message with AES. That hybrid approach is how TLS, PGP and most real systems work.
It uses RSA-OAEP with SHA-256, the modern padding scheme that resists the chosen ciphertext attacks that older PKCS version 1 padding allowed.
No. Keys are generated inside your browser with the Web Crypto API and stay in the page until you close it or replace them.
The public key encrypts and can be shared freely. The private key decrypts and must be kept secret, because anyone holding it can read your messages.
Yes, a key pair can be used for many messages. You can paste the exported PEM text into the boxes later to import the same pair again.
Any modern browser with the Web Crypto API supports RSA-OAEP, including recent versions of Chrome, Edge, Firefox and Safari on desktop and mobile.
Yes. The tool is completely free and unlimited, with no account, no sign-up and no upload of any key or message.

Last updated: October 10, 2026