I am using rsa key to encrypt a long string which I will send to my server(will encrypt it with server's public key and my private key) But it throws an exception like javax.crypto.IllegalBlockSizeException: Data must not be longer than 256 bytes
I feel that I have not understood the working of rsa properly till now(using the inbuilt libraries are the cause for this).
Can some one please explain why this exception is being thrown. Is it not at all possible to send long string encrypted?
Java – getting a IllegalBlockSizeException: Data must not be longer than 256 bytes when using rsa
encryptionjavarsa
Best Answer
So basicly you divide the key length with 8 -11(if you have padding). For example if you have a 2048bit key you can encrypt 2048/8 = 256 bytes (- 11 bytes if you have padding). So, either use a larger key or you encrypt the data with a symmetric key, and encrypt that key with rsa (which is the recommended approach).
That will require you to: