[Gpg4win-users-de] Descrypt using signature key on OpenPGP card?

[Werner Koch]

On Tue,  7 Apr 2015 13:36, felix.klee at inka.de said:

> The key that I uploaded to the [key server][2] is my signature key.
> Now someone sent me a message encrypted with that key.
>
> *Is it possible to decrypt that message using the smartcard?*

The default for OpenPGP is to generate a primary signature key (mainkey)
and a secondary encryption key (subkey).  They are cryptographically
glued together and in most cases the user only sees the mainkey. 

It is always better to use one key for one task and not to use one key
for encryption and signatures.  Another reason why OpenPGP does this is
related to patents.  In April 1997 one public key patent expired and it
was possible to use the DSA and the Elgamal algorithms.  However, DSA
can only be used for signing and Elgamal is better only used for
encryption.

The smartcard stores these two keys and also a third one which may for
example be used for ssh.


Salam-Shalom,

   Werner

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