Linux crypto killer apllication

[Bill Royds]

On 15-May-08, at 15:48 , David Picón Álvarez wrote:

>
> RSA is more flexible. Easier to protect several documents, easier to  
> have shared secrets, etc
You don't seem to understand the difference between public key an  
secret key encryption.
RSA is not used to encrypt the document. RSA is used to encrypt the  
key that is used to encrypt the document. The key is a shared private  
key that is transmitted using a PK system like RSA.

IF you want to save encrypted data for a long time, you encrypt it  
with a sufficiently long private key (generated at random), such as as  
AES 512. You then encrypt that key with the public keys of everybody  
that needs to know the key to decrypt the document. Since the private  
key is fairly short in bytes and random, it has a full entropy, so  
would be hard to decrypt by random guessing.
If you are worried by key size, it is the key size of the AES cypher  
that you need to worry about, not RSA.