Question 1

Are the generated keys secure? Will the private key be uploaded?

Accepted Answer

The key pair is generated entirely locally by the browser's native Web Crypto. The private key is never uploaded or leaves your device. Exports are in standard PEM format (public key SPKI, private key PKCS#8), compatible with other RSA-OAEP supported systems. Keep the private key secure; if leaked, anyone can decrypt the ciphertext sent to you.

Question 2

Why can RSA only encrypt very short content?

Accepted Answer

RSA is an asymmetric algorithm, and the maximum data it can encrypt per operation is approximately 'key length ÷ 8 − 66' bytes (e.g., 2048-bit is about 190 bytes). In practice, RSA is often used to encrypt a random AES key, and then AES encrypts the content. If you need to encrypt long text, please use this site's AES tool directly.

Question 3

What key length should I choose?

Accepted Answer

2048-bit is the current general security lower limit, balancing speed and security; for scenarios requiring higher long-term confidentiality or compliance, 3072 or 4096-bit can be chosen, but generation and computation will be slower. This tool uniformly uses RSA-OAEP(SHA-256) padding, which is more secure than the older PKCS#1 v1.5.

RSA Key Generator

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RSA Encryption/Decryption (Short Data)

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