iPhone data encryption failed to read my sqlite after used - ios

Question

i want to secure my sqlite database store in doc directory. so i used this for encryption.
[fileManager createFileAtPath:databasePath contents:[#"super secret file contents" dataUsingEncoding:NSUTF8StringEncoding] attributes:[NSDictionary dictionaryWithObject:NSFileProtectionComplete forKey:NSFileProtectionKey]];
My code is like this
-(void)createDatabase
{
// Setup some globals
NSString *databaseName = #"Sample.sqlite";
// Get the path to the documents directory and append the databaseName
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [documentPaths objectAtIndex:0];
NSString *databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
// Check if the SQL database has already been saved to the users phone, if not then copy it over
BOOL success;
// Create a FileManager object, we will use this to check the status
// of the database and to copy it over if required
NSFileManager *fileManager = [NSFileManager defaultManager];
// Check if the database has already been created in the users filesystem
success = [fileManager fileExistsAtPath:databasePath];
// If the database already exists then return without doing anything
if(success)
return;
// If not then proceed to copy the database from the application to the users filesystem
// Get the path to the database in the application package
NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:databaseName];
// Copy the database from the package to the users filesystem
[fileManager copyItemAtPath:databasePathFromApp toPath:databasePath error:nil];
[fileManager createFileAtPath:databasePath contents:[#"super secret file contents" dataUsingEncoding:NSUTF8StringEncoding] attributes:[NSDictionary dictionaryWithObject:NSFileProtectionComplete forKey:NSFileProtectionKey]];
}
-(void)opendb
{
sqlite3 * database;
NSString *databasename=#"Sample.sqlite"; // Your database Name.
NSArray * documentpath=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSAllDomainsMask, YES);
NSString * DocDir=[documentpath objectAtIndex:0];
NSString * databasepath=[DocDir stringByAppendingPathComponent:databasename];
if(sqlite3_open([databasepath UTF8String], &database) == SQLITE_OK)
{
const char *sqlStatement = "SELECT * FROM Sampletable"; // Your Tablename
sqlite3_stmt *compiledStatement;
if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK)
{
while(sqlite3_step(compiledStatement) == SQLITE_ROW)
{
[Rollnumber addObject:[NSNumber numberWithInt:(int)sqlite3_column_text(compiledStatement,0)]];
[Name addObject:[NSString stringWithFormat:#"%s",(char *) sqlite3_column_text(compiledStatement, 1)]];
}
}
sqlite3_finalize(compiledStatement);
}
sqlite3_close(database);
}
Roll number and name not being access.
but when i removed this line
[fileManager createFileAtPath:databasePath contents:[#"super secret file contents" dataUsingEncoding:NSUTF8StringEncoding] attributes:[NSDictionary dictionaryWithObject:NSFileProtectionComplete forKey:NSFileProtectionKey]];
once again properly work but i want to encrypt my database using this code so how may i aceess my sqlite content. means how may i decrypt when i want to use.
please help me to do this.
Thanks in advance.
my db encrypt successfully. but when i want to access the sqlite. not get the data.
so how may i do this thanks in advance.

Answer 1

You should consider using SQLCipher, that should completely do what you want. SQLCipher was already discussed here: Encrypting SQLite database file on iOS
If you want to roll something yourself, you will have to read the full database into memory, use some decryption code of your now and save the encrypted version as you try above. This nevertheless isn't too easy to do if you have to stay within memory limits for example. Also, to access the database you have to encrypt it and probably store temporarily on disk. This makes it accessible again.