[Botan-devel] Decrypt signature

[Stefan Misslinger]

Hi,

i'm currently trying to get the following to work.

We have an application that reads encrypted files, which are AES
encrypted with an RSA enrypted AES key in the header.

For the application to decrypt the files, we had to integrate the
private key also into the source code.
In the case someone would manage to extract the key from the source,
we want to prevent the attacker from being able to create his own
encrypted files.

My solution to that would have been to sign the AES key with my
private RSA key. The application should then use the public RSA key to
decrypt the files.

Is it possible to decrypt the signature and therefore reconstruct the
encrypted(signed) AES key?
As far as I've seen its only possible to verify if the signature is
correct. I didn't find any example how to recover the message as well.

Thanks in advance and greetings from Munich,
Stefan