Signing and symmetrically encrypting files

[Bernhard Reiter]

Hi Arbiel,

Am Mittwoch 14 September 2016 17:28:59 schrieb Arbiel (gmx):
> Asymmetric encryption requires the recipients to use my public key to
> get access the documents, whereas symmetric encryption only requires
> them to key in the encryption key. 

for decryption, only the private key of the recipient is needed.
Typing in that passphrase is as difficult (or easy) as typing in the symmetric 
key. Of course asymmetric crypto would need them to create a key-pair first.
But symmetric encryption has the problem of you needing to transfer the keys 
each time.

> Obviously the recipients who are not 
> confident enough with using asymmetric encryption won't be able to
> verify the authentity of the documents, but this a least drawback.
>
> However, if I can't sign and encrypt in a single step, I'll sign and
> then symmetrically encrypt the signed document, or the other way around.

Usually you sign first and then encrypt. This way the signature stay 
verifiable even after decryption.

> I forgot to write that I want the process (sign and encrypt) to procede
> without any keyboard-typing.

A passphrase is not needed for asymmetric encryption.
It is only needed to unlock your private key for signing.
If you want to build an automated system, one way is to just have a private 
key without passphrase (and secure the system). There are other ways of 
course.

> My previous message seems to have been a HTML message. I unchecked the
> control and hope this answer is a clear text message

Yes, it is. :)


Best Regards,
Bernhard

-- 
www.intevation.de/~bernhard   +49 541 33 508 3-3
Intevation GmbH, Osnabrück, DE; Amtsgericht Osnabrück, HRB 18998
Geschäftsführer Frank Koormann, Bernhard Reiter, Dr. Jan-Oliver Wagner
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