Check the certificate of an APK

Following previous post, if you lost your certificate file, you have 2 problems
1/ you won't be able to update your APK on the market anymore
2/ you are unable to retrieve details about the certificate used

While there is NOTHING to do for the first problem, there is a way to retrieve the certificate information.

Coming with jdk, you should use jarsigner :

jarsigner.exe -verify -certs -verbose <app>.apk

For each file of the apk, it will give you something similar to

X.509, CN=WillNa, OU=, O=, C=FR
[certificate is valid from 19/12/10 08:38 to 19/12/35 08:38]

this is the certicate details available.

Retrieve information from your p12 certificate

Some days ago, one of my distributors asked me a package with a 30 years long certificate. I was pretty sure my current package was long enought but I didn't remember how much so I looked for a way to get it from this cryptic p12 file.


Be sure you have a jdk and not a jre installed else keytool won't be available.
The command to read information from a .p12 certificate is

keytool -list -keystore <certificate_file>.p12 -storetype pkcs12 -v

the magic option is -v
This way you could see the full informations

My p12 was 25 years long, it seems Google asks 30 years long now

Warning : it's not possible to update the certificate, the only way is to create a new one with the same informations and 30 years validity.
Sadly, doing this cancels the update system of Android.
Current users won't be able to update your app with the previous certificate, they have to delete and redownload it.

So backup and double backup your certificate !

Monetize 'cheap' apps

Interesting post on InMobi's blog

It tries to explain you how much you could win in releasing ads based apps vs paid apps.
Of course, you shouldn't forget it for CHEAP apps only !

The side note of this post is that you have 2 ways to monetize your apps : ads or update your sell price ;)

Another even more interesting thing of this post is the linked Excel sheet : it allows you to quickly find if you will earn more advertising your app.

I made a test myself:
* for apps will a small number of downloads, the answer is defintly "NO"
* for 1M+ downloads, the answer is "YES"
Like for money, the more download you have, the more download you'll get !