[Botan-devel] Big buffer encryption \ decryption using RSA.

Jack Lloyd lloyd at randombit.net
Wed Jun 6 10:36:51 EDT 2007


On Wed, Jun 06, 2007 at 06:21:56PM +0400, ?????? wrote:
> Wea are developing the system that works similar to PGP mail encryption.
> PGP uses RSA for mail encryption. 
> We want to use the similar approach

PGP does not use RSA for bulk encryption. It encrypts a small (128 to
256 bits, typically) key with the RSA operation, and then encrypts the
file with a much faster symmetric cipher like AES or 3DES.

If you really want to pursue this path of encrypting entirely with
RSA, you'll need to split up the file and concatenate each individual
RSA encrypted output. It will be vulnerable to message reordering
attacks, and be atrociously slow (bit for bit, AES is around 50 times
faster than RSA).

-Jack



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