Now that we have improved the signature verification result messages, I'd like to continue with other result windows.
This is a current successful result message in a KF6 version:

Like for the signature verification results, the sign and/or encrypt result should get a green background if no error occurred. Additionally we should add the green check mark icon on the left side of the text.
In case of error, use red background + the red X icon.
If the encryption is not VS-compliant in case of a VSD installation we could maybe only add the green icon but no green background. (The Finish button (and the encrypt button in the previous window) is red in that case.

Furthermore the message could be a bit better visually structured.

Current text for sign+encrypt:
"Successfully signed and encrypted <filename>%1</filename> and saved it as <filename>%2</filename>."
Maybe better:
"Successfully signed and encrypted <filename>%1</filename>.\nOutput file: <filename>%2</filename>."