Use the jarsigner tool:
jarsigner -verify -verbose -keystore keystore_file apk_file.apk
This command gives output as follows:
smk 22401 Tue Aug 30 10:20:52 SAMST 2011 res / drawable / about_cover.png
smk 1206 Tue Aug 30 10:20:52 SAMST 2011 res / drawable / add_normal.png
smk 1430 Tue Aug 30 10:20:52 SAMST 2011 res / drawable / app_icon.png
smk 133 Tue Aug 30 10:20:52 AM SAMST 2011 res / drawable / background_next_section.png
s = signature has been verified
m = entry specified in manifest
k = at least one certificate was found in the keystore
Sergey Glotov
source share