The Flag was in MainActivity only, Simply I was digging the Apk source code.

which folder is the Java source code ? i have de-compiled and unzipped the apk then l was greeted with a lot of folder

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Super Easy !

I also jumped out of my chair when I solved it! Good challenge.

easy one

Ive been told by a number of users that they have had issues with the md5 portion of this challenge. As cracking it was not the focus point I have provided a link below to a website that will successfully decrypt it.

https://www.md5online.org/md5-decrypt.html

My very first RE. I loved that the flag was not given as a single piece. Nicely done. Thank you

which folder is the Java source code ? i have de-compiled and unzipped the apk then l was greeted with a lot of folder

Excellent! I learned to use 2 new online tools, one to decompile the api file and the other to decode the MD5 hash.

Thanks your hint

To be honest, this was best. Here's the hint: use apktool , dex-tools and jd-gui. Newbie you will surely enjoy this.

This is a good one. You can use apktool on linux, but use it only if you are a little familiar with assembly. Otherwise use one of the online tools mentioned in the comment.