RSA Encrypt & Sign
Free online RSA key generator, encryption/decryption and signing/verification. Standard PEM keys, Web Crypto local processing, 2048/3072/4096-bit support.
Keys are generated locally in your browser (Web Crypto API). 2048-bit takes about 1 second; 4096-bit can take ten seconds or more
FAQ
What key format is generated?
Standard PEM: public keys are SPKI (BEGIN PUBLIC KEY) and private keys are PKCS#8 (BEGIN PRIVATE KEY) — directly importable into OpenSSL, Java, PHP, Python and most backends.
Which algorithms are used?
Encryption uses RSA-OAEP (SHA-256); signing uses RSASSA-PKCS1-v1_5 (SHA-256, i.e. the Java default SHA256withRSA). 1024-bit keys are too weak and no longer offered.
Is my private key safe?
Yes. Key generation, encryption and signing all run locally via Web Crypto. Nothing is stored — keys vanish on refresh, and you should not use untrusted devices.
Is there a size limit for encryption?
Yes. RSA encrypts at most (key bits ÷ 8 − padding) bytes per call (about 214 bytes at 2048-bit). For long text, encrypt with AES first and wrap the AES key with RSA (hybrid encryption).