The Kaspersky Sandbox distribution kit includes digital signatures of installation files in separate files with the .sig extension:
You can request the Kaspersky Research Sandbox OpenPGP public key (the ksb.crt.pgp certificate) on the Technical Support website and use it to verify digital signatures of installation files.
To verify the digital signature using GnuPG,
run the following command:
gpg --no-default-keyring --keyring ./ksb.crt.pgp --verify ./ksb_2.0.0.500.x86_64_en_ru.iso.sig ./ksb_2.0.0.500.x86_64_en_ru.iso