Android Question Why SQLCipher database is bigger and can not be compressed?

[susu]

Hi guys,
I got 2 problems and I want to hear your thought:

1. Based on a SQL database (file size 85MB) I create new SQLCipher database but its size is bigger (90MB). I don't understand why.

2. When I compile with the old SQL database named "data.db" => Result apk file size is only 28MB because the database is compressed. But when I compile with new SQLCipher database named "datacipher.db" => Result apk file size is 93MB! The reason is "datacipher.db" is not compressed and I don't know why too.

Did you face that problems? Please share your idea/solution. Thank you so much.

 

[Erel]

1. SQLCipher encrypts the data before it is saved. It might be slightly bigger. The difference in this case is pretty small (5%).
2. You cannot compress encrypted data as the data is more or less "random".

 

[susu]

1. OK, I got it.
2. Is there a way to handle it? My app is so big for the users.

 

[Erel]

It is not possible to compress encrypted data. Does all of this data need to be compressed? Maybe you can use a different solution that only compresses the sensitive columns?

 

[susu]

The database is simple with 3 columns: id, text1, text2. Each text have 5,000 - 10,000 words. And total 22,500 records. I need to encrypt it because it's exclusive content.
I tried to encrypt the content then add to database but the result is bigger than SQLCipher database so I really stuck in this problem.

 

[DouglasNYoung]

Surely the solution is to compile the app with an empty database and when the app first runs download the filled database from a web server. This would also have the advantage of being able to update the system without recompiling a new apk.

Douglas

 

[susu]

Surely the solution is to compile the app with an empty database and when the app first runs download the filled database from a web server. This would also have the advantage of being able to update the system without recompiling a new apk.

Douglas

The problem is with SQL database, my app (apk file) is only 28MB. After encrypt database with SQLCipher it growns up to 90MB (only database file). I don't think the users want to download that huge file.

 

[Erel]

You can try to compress the strings and then add them as blobs to the encrypted database.

You can compress them with CompressedStreams from the RandomAccessFile library.

 

[susu]

The compressed SQLCipher database is 36MB. It's still quite big but acceptable.

Thank you very much.