how can I verify software via (PGP Signature) ?

[drugo]

Hi

i use few paid software and many free software

today I downloaded kid3 ,an audio tag editor 

i used to use hash to compare the downloaded file to be sure it's safe

but this is the second time that i haven't found an hash but a PGP file , with extension *.sig

 

to calculate hash ,there are several free and portable software

how can i use this sig file?

is there a free stealth portable software to check the program is safe like an hash program?

i have always associate PGP to emails

thanks

sorry for my poor english