如何使用非对称加密技术加密大量数据？

Question

In the client side of my application I want to encrypt text (that could be of any size) using a public key. After that I'll send this packet to a server. In the server side I want to decrypt this packet using my private key.

I can't use RSA, because the packet size could be of any size, even bigger then the key. I can do that using OpenSSL, creating files and stuff with the results of Encrypt/Decrypt.

The question is: is there another way to programmatic do that?

Answer 1

You need to implement a hybrid encryption scheme . One example of such a scheme is OpenPGP.

In a hybrid encryption scheme, one generates a symmetric session key that is used just for one message. The symmetric key encrypts the payload, while the public key of the recipient(s) is used to encrypt the symmetric key. The payload is often signed by the private key of the sender. Finally, the whole lot is packaged together and sent out the door.

I would recommend you use something like BouncyCastle to do OpenPGP encryption in Java. No need to reinvent the wheel.

Answer 2

Use either PKCS#7/CMS or OpenPGP depending on whether you prefer to deal with X.509 certificates (they can be self-signed) or PGP keys. Both technologies provide comparable level of security and the differences (in case of your task) are mainly in the key format.

BouncyCastle or our SecureBlackbox are the widely used libraries suitable for both variants.