SQLite + SQLCipher + FMDatabase on iOS - ios

Question

I'm currently using FMDatabase in my iOS app and I'm very happy with it.
I plan to encrypt the sqlite database with SQLCipher.
Here are my questions:
1) Are FMDatabase and SQLCipher compatibles ? I think I just need to add a new method in FMDatabase called openEncrypted...and do the job for SQLCipher. I hope all FMDatabase methods will work.
2) Actually, I have 2 databases in my app. Then I do an ATTACH DATABASE in my app to join them. I would like to encrypt just one of the two. Will it work or I need to encrypt the 2 databases ? (One is critical, the other is not)
3) I don't really understand what I will have to provide to Apple (documents) if I encrypt these files.
Thanks you !

Answer 1

For those looking for a simple tutorial on how to accomplish this, I was able to create one: http://www.guilmo.com/fmdb-with-sqlcipher-tutorial/
But the most important parts are, Opening your existing DB and attaching a new encrypted one. Then setting the key in your FMDB connections.
SQLCipher - Encrypting the database
// Import sqlite3.h in your AppDelegate
#import <sqlite3.h>
// Set the new encrypted database path to be in the Documents Folder
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDir = [documentPaths objectAtIndex:0];
NSString *ecDB = [documentDir stringByAppendingPathComponent:#"encrypted.sqlite"];
// SQL Query. NOTE THAT DATABASE IS THE FULL PATH NOT ONLY THE NAME
const char* sqlQ = [[NSString stringWithFormat:#"ATTACH DATABASE '%#' AS encrypted KEY 'secretKey';",ecDB] UTF8String];
sqlite3 *unencrypted_DB;
if (sqlite3_open([self.databasePath UTF8String], &unencrypted_DB) == SQLITE_OK) {
// Attach empty encrypted database to unencrypted database
sqlite3_exec(unencrypted_DB, sqlQ, NULL, NULL, NULL);
// export database
sqlite3_exec(unencrypted_DB, "SELECT sqlcipher_export('encrypted');", NULL, NULL, NULL);
// Detach encrypted database
sqlite3_exec(unencrypted_DB, "DETACH DATABASE encrypted;", NULL, NULL, NULL);
sqlite3_close(unencrypted_DB);
}
else {
sqlite3_close(unencrypted_DB);
NSAssert1(NO, #"Failed to open database with message '%s'.", sqlite3_errmsg(unencrypted_DB));
}
self.databasePath = [documentDir stringByAppendingPathComponent:#"encrypted.sqlite"];
Note that we set 2 parameters in SQL Query, the DATABASE and the KEY. The DATABASE should be the full path to the encrypted database you want to create, in this case, string ecDB, and the KEY parameter is the key that’s going to be use to ENCRYPT your database, so choose a strong one
Now on your FMDB functions, call [db setKey:#"strongKey"] after every time you open the db.
// FMDatabase Example
FMDatabase *db = [FMDatabase databaseWithPath:[self getDatabasePath]];
[db open];
[db setKey:#"secretKey"];
// FMDatabaseQueue Exmple
FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:[self getDatabasePath]];
[queue inDatabase:^(FMDatabase *db) {
[db setKey:#"secretKey"];
...
}];
Let me know if you have any questions!

Answer 2

Yes, You still need to compile in SQLCipher, but you can use FMDB. FMDB also provides a function to set the encryption key for the database
You can attach a non-encrypted database to an encrypted database (see http://sqlcipher.net/sqlcipher-api/#attach)
You will generally need to do an encryption registration with the DOC and then self-classify as mass market http://www.bis.doc.gov/encryption/question4.htm

Answer 3

Hi I am using swift and following is the code I follow. But I have one problem the encrypted.sqlite file I can open with SQLiteBrowser what I was wrong here.
var db: COpaquePointer = nil;
let databasePath = FileUtils.getPath("data.db")
var ecDB = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)[0].stringByAppendingPathComponent("encrypted.sqlite")
let result = String.fromCString("ATTACH DATABASE \(ecDB) AS encrypted KEY TaP")
if (sqlite3_open(databasePath, &db) == SQLITE_OK) {
sqlite3_exec(db, result!, nil, nil, nil);
sqlite3_exec(db, "SELECT sqlcipher_export('encrypted');", nil, nil, nil);
sqlite3_exec(db, "DETACH DATABASE encrypted;", nil, nil, nil);
sqlite3_close(db);
}
else {
sqlite3_close(db);
sqlite3_errmsg(db);
}