When trying to import an S/MIME certificate backed-up from Firefox using a long passphrase, importing the p12 file in Kleopatra fails with the error: Decryption failed.

This is bad in two ways:
a) it should just work (using long passphrases is advertised)
b) the error message doesn't point to the actual problem at all - the user might not at all get the idea that a too long passphrase is the problem

The issue might be related to https://bugs.kde.org/show_bug.cgi?id=362640 but I'm not too sure, especially since this is an entire different use-case and error message.

Reproducible: Always

Steps to Reproduce:
1. Get an S/MIME certificate in Firefox (normal case, when creating a certificate via the webbrowser - for instance via CAcert).
2. In Firefox: Tools -> Options -> Advanced -> View Certificates
3. Select your certificate -> Backup...
4. Enter a filename where to store the p12-file
5. Enter the master password, if required
6. Use the following password to encrypt the p12-file: 0f9guf9dhgsadi90sdg0ßfd0hdgj0df
7. In Kleopatra: File -> Import certificate...
8. Select the p12-file saved earlier
9. Enter the password: 0f9guf9dhgsadi90sdg0ßfd0hdgj0df
10. Enter a random passphrase to protect the imported object - for instance test1234 and confirm it once more

Actual Results:  
Error shows up:
Title: Certificate Import Failed - Kleopatra
An error occurred while trying to import the certificate [filename].p12:
Decryption failed

Expected Results:  
Import of certificate succeeds.

The error doesn't occur, when using a shorter password to create the backup of the certificate from Firefox.