I see a lot of code where user id's, passwords or other critical Information is stored inside the code. Problem here is that the code can be decompiled very easy and someone can extract the information or the logic of your app. Even if you put it to the assets folder does not work.
Another trap is to store config parameters in a normal textfile. This can be edited by any user.
For this reason you must encrypt all critical data you want to use. Good idea you might think but where do I store the password for that?
Inside the app isn't very clever as I mentioned before, but we have to take a look at our app and what we want to do/protect. Here are some typical situations and how to do it. Please feel free to comment own ideas to improve this post. Please don't post any questions like "how do I use httputils, encryption, php, MySql, etc.). See other examples/Posts for this.
Example 1: A simple app which doesn't communicate over the internet but you need to protect a config file or other data
- at the start check if your (encrypted) config/data file is already there (File.Exists...)
- if not you know that this is the first start
- ask for a password
- create a RAF file and store all data you want with RAF.WriteEncrypted & the given password
- at the next start you will find the file
- ask for the pw
- read the contents with RAF.ReadEncrypted
Benefits: Because the user has to give the pw at every start, it's safe. Of course someone could decrypt the file knowing his own pw but this doesn't make sense because he only sees his stored data or some configurations. The normal user has no chance to do this.
Example 2: An app which communicates over the internet (httputils -> php/MySql) OR you can upload a file to a webspace (folder)
- even better
- in your app ask for a userid and a pw
- create the RAF file (Example 1), name it like the userid /f.e. "peter.dat) and upload it to the server/webspace
- store the file in a folder (webspace) or in a MySql db (I never store Blobs/files there, only the index)
- delete the local file
- at the next start ask for the userid and pw
- get the file from the folder, MySql db, etc.
- store it local
- read the contents
- delete the file
Benefits: There is no chance to get the file unless you know the userid. Knowing it, you can donwload the file but you'll need the pw (which only the user knows). On the device someone can get the file when he's fast enough but he has to know the pw.
Pro version: Let php create the folder and a .httaccess file with the same user & pw (so the folder is protected). Even a download will not work then if you don't know the userid AND the pw
Example 3: Combinations with other encryption methods (RSA)
Why RSA? All B4x Versions can use it (lib) and the rest of the world (Servers, VS 201x, etc.) and handling the keys is very easy.
At the point when you transmit the userid & the pw to a webserver it is unsafe again. Someone with deeper skills could sniff the data stream an get the userid & pw. Therefore I use RSA to encrypt the meta data (=userid & pw).
RSA uses 2 keys: The public key which is indeed public (everyone may have it) and the private key (which is for your eyes only). In my examples you have 2 clients who want to communicate with: Your app and the server. Each of them then has an own pub and private key.
In this example I use only the App -> Server en-/decryption because you only want to protect your userid & pw while sending it to the server. Forget the RAF file -> we will handle it all on the server
How it works (with php):
- create a public key (with OpenSSL -> see my examples -> has to be done only ONE time)
- store it in a open folder on the server (it is public to anyone) or in a database (ONE time)
- in your app get the server's pub key via httputils
- put the data (userid, pw AND your data which was in the RAF file before) in a List with maps to a JSON-string
- encrypt data with the server's key (use encryption library and see my examples)
- send it to the server PHP-script
- decrypt it via OpenSSL
- store it in a file or better in a MySQL db
- at the next start of your app
- get the server's pub key again
- send an encrypted request (httputils) to the server again ("GetMyData") with your userid & pw
- decrypt it on the server
- get the data from the file or db
- send it to the app
Benefits: All the critical data is encrypted, even during the Transmission except the data/config.
Pro version: Encrypt/Decrypt both sides (app to server, server to app)
SqlLite (local db on your device) without any extension:
- as the db is just a file you could RAF encrypt it
- when you need it, just decrypt to the temp db-file
- closing the app. encrypt it again and delete the temp file
Problem: any skilled user can copy the temp file and Play with it
Q: Why do you use it "that way"?
A: Most likely you need to collect data and then sync/update the data with a server-db. This is a nice way to do that, but ... If you only collect data which will be void later by transfering it to another (remote) db, you could use a RAF file for that which is encrypted.
Q: But I need the data for a longer time and I need fast access to it
A: How much rows are we talking about? 20? 50? 100? Then just put them to a RAF file and load it into a list
Q: I have 100.000+ records in my db. I need a db!
A: Why do you have so many records on a phone/tablet? What do you do with the data (except creating a very personal Wikipedia)? Think about the concept of your app.
Q: I don't care - I want to have my 100K+ rows on my device!
A: Then do it, but - at least - encrypt the data itsself...
Notes:
- Base64 is NOT and encryption but a helper. It will convert your data to a format all clients can convert back and there's no loss of formats on the way. Use it as a standard in all of your Projects, even if you stay in the B4x world.
- don't use Services/libs where you have to give a user & pw in the code of your app.
Another trap is to store config parameters in a normal textfile. This can be edited by any user.
For this reason you must encrypt all critical data you want to use. Good idea you might think but where do I store the password for that?
Inside the app isn't very clever as I mentioned before, but we have to take a look at our app and what we want to do/protect. Here are some typical situations and how to do it. Please feel free to comment own ideas to improve this post. Please don't post any questions like "how do I use httputils, encryption, php, MySql, etc.). See other examples/Posts for this.
Example 1: A simple app which doesn't communicate over the internet but you need to protect a config file or other data
- at the start check if your (encrypted) config/data file is already there (File.Exists...)
- if not you know that this is the first start
- ask for a password
- create a RAF file and store all data you want with RAF.WriteEncrypted & the given password
- at the next start you will find the file
- ask for the pw
- read the contents with RAF.ReadEncrypted
Benefits: Because the user has to give the pw at every start, it's safe. Of course someone could decrypt the file knowing his own pw but this doesn't make sense because he only sees his stored data or some configurations. The normal user has no chance to do this.
Example 2: An app which communicates over the internet (httputils -> php/MySql) OR you can upload a file to a webspace (folder)
- even better
- in your app ask for a userid and a pw
- create the RAF file (Example 1), name it like the userid /f.e. "peter.dat) and upload it to the server/webspace
- store the file in a folder (webspace) or in a MySql db (I never store Blobs/files there, only the index)
- delete the local file
- at the next start ask for the userid and pw
- get the file from the folder, MySql db, etc.
- store it local
- read the contents
- delete the file
Benefits: There is no chance to get the file unless you know the userid. Knowing it, you can donwload the file but you'll need the pw (which only the user knows). On the device someone can get the file when he's fast enough but he has to know the pw.
Pro version: Let php create the folder and a .httaccess file with the same user & pw (so the folder is protected). Even a download will not work then if you don't know the userid AND the pw
Example 3: Combinations with other encryption methods (RSA)
Why RSA? All B4x Versions can use it (lib) and the rest of the world (Servers, VS 201x, etc.) and handling the keys is very easy.
At the point when you transmit the userid & the pw to a webserver it is unsafe again. Someone with deeper skills could sniff the data stream an get the userid & pw. Therefore I use RSA to encrypt the meta data (=userid & pw).
RSA uses 2 keys: The public key which is indeed public (everyone may have it) and the private key (which is for your eyes only). In my examples you have 2 clients who want to communicate with: Your app and the server. Each of them then has an own pub and private key.
In this example I use only the App -> Server en-/decryption because you only want to protect your userid & pw while sending it to the server. Forget the RAF file -> we will handle it all on the server
How it works (with php):
- create a public key (with OpenSSL -> see my examples -> has to be done only ONE time)
- store it in a open folder on the server (it is public to anyone) or in a database (ONE time)
- in your app get the server's pub key via httputils
- put the data (userid, pw AND your data which was in the RAF file before) in a List with maps to a JSON-string
- encrypt data with the server's key (use encryption library and see my examples)
- send it to the server PHP-script
- decrypt it via OpenSSL
- store it in a file or better in a MySQL db
- at the next start of your app
- get the server's pub key again
- send an encrypted request (httputils) to the server again ("GetMyData") with your userid & pw
- decrypt it on the server
- get the data from the file or db
- send it to the app
Benefits: All the critical data is encrypted, even during the Transmission except the data/config.
Pro version: Encrypt/Decrypt both sides (app to server, server to app)
SqlLite (local db on your device) without any extension:
- as the db is just a file you could RAF encrypt it
- when you need it, just decrypt to the temp db-file
- closing the app. encrypt it again and delete the temp file
Problem: any skilled user can copy the temp file and Play with it
Q: Why do you use it "that way"?
A: Most likely you need to collect data and then sync/update the data with a server-db. This is a nice way to do that, but ... If you only collect data which will be void later by transfering it to another (remote) db, you could use a RAF file for that which is encrypted.
Q: But I need the data for a longer time and I need fast access to it
A: How much rows are we talking about? 20? 50? 100? Then just put them to a RAF file and load it into a list
Q: I have 100.000+ records in my db. I need a db!
A: Why do you have so many records on a phone/tablet? What do you do with the data (except creating a very personal Wikipedia)? Think about the concept of your app.
Q: I don't care - I want to have my 100K+ rows on my device!
A: Then do it, but - at least - encrypt the data itsself...
Notes:
- Base64 is NOT and encryption but a helper. It will convert your data to a format all clients can convert back and there's no loss of formats on the way. Use it as a standard in all of your Projects, even if you stay in the B4x world.
- don't use Services/libs where you have to give a user & pw in the code of your app.
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