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Configuration
Encrypt, decrypt, and sign using RSA-OAEP, RSA-PSS, ECDSA, and Ed25519 public/private key pairs. Generate a key pair or paste your own, enter the text, and select the desired mode. Encryption uses the public key; decryption and signing require the private key.

RSA with OAEP padding. Asymmetric: encrypts with public key, decrypts with private key.

Keys and parameters
Public key (PEM)
Private key (PEM)
Entrance

How it works

Asymmetric cryptography uses a key pair: a public one, which is shared, and a private one, which is kept secret. What is processed with one key is resolved with the other.

Depending on the algorithm you can encrypt and decrypt (RSA-OAEP, X25519) or sign and verify (RSA-PSS, ECDSA, Ed25519). Generate a key pair or paste your own in PEM format, choose the mode, and everything is processed in your browser.

To encrypt, you use the recipient's public key and only their private key can decrypt. To sign, you use your private key and anyone verifies with your public key, confirming the authorship and integrity of the message.

Examples

RSA-OAEP · 2048 bitsEncrypt with the public key → decrypt with the private key.
Ed25519Sign with the private key → verify with the public key.Ed25519 uses 32-byte keys and 64-byte signatures; it is very fast and secure, recommended for new applications.
ECDSA · P-256Signature over an elliptic curve, more compact than RSA for equivalent security.

Use cases

  • Send a message that only the recipient can read, encrypting it with their public key.
  • Sign a document or message so anyone can check that it comes from you and was not altered.
  • Verify the signature of a file or message with its author's public key.
  • Generate test key pairs (RSA, ECDSA, Ed25519, X25519) when developing a cryptographic flow.

Frequently asked questions

How does it differ from symmetric encryption?

Symmetric uses a single shared key; asymmetric uses a public/private pair. Asymmetric solves the key exchange problem, but is slower, so it is usually combined with symmetric encryption.

What is a key in PEM format?

It is a text representation of the key, Base64-encoded between headers like -----BEGIN PUBLIC KEY----- and -----END PUBLIC KEY-----. It is the usual format for exporting and importing keys.

When to use RSA and when elliptic curves?

Elliptic curves (ECDSA, Ed25519) offer much smaller keys and better performance for equivalent security. RSA remains relevant mainly for compatibility with existing systems.

What is the difference between encrypting and signing?

Encrypting protects confidentiality: the public key encrypts and the private key decrypts. Signing proves authenticity: the private key signs and the public key verifies that the message is genuine and unchanged.

Can I encrypt large files with RSA?

Not directly: RSA only encrypts small data. In practice, hybrid encryption is used, encrypting the content with a symmetric algorithm and protecting only that key with RSA.

Are my keys sent to a server?

No. Key generation, encryption, signing, and verification happen entirely in your browser; the keys never leave your device.

See also