After generating a file, I don't want to allow anyone to open it.
How do I protect it, by using a password?
Is there any better way?
How do I do it programmatically?
What are you trying to protect and who are you protecting it from?
If you're going to put your credit card number in it and ship it off to the Russian Mob, then you'd need rather strong encryption. If you're trying to obfuscate the contents from standard users, a simple ASCII shift would be OK.
.Net has encryption routines built in. The Code Project (nice site, by the way) has a good article those encryption routines here.
If you're the administrator of the machine, and those you are trying to protect the contents from are not administrators, then simply change the permissions of the file.
A CSV file is just a text file. It doesn't have any protection of its own.
You could encrypt it, or zip it up (with a password), for example. But then you will need to decrypt it/unzip it before you could use it.
You have a couple of options.
1) You could Encrypt the file. Then even if people can open the file they won't be able to read it.
2) Zip it up and password protect it. See dotnetzip from codeplex.
Related
I have a website that has the old "list files" style of doing things, and I want to perform a hash on a file there before downloading it to the user's local system. I know how to hash a local file, but it seems there's not a lot of info as to whether or not I can do this without downloading the online file. My logic is, if the user already has the same file, why waste time downloading it? So, is it possible to do this?
After further contemplation I decided that the date modified comparison is actually the behavior that I want. If a client were to modify a file on accident, there is now an option to correct it. If they modify it on purpose, I certainly don't want to wipe out their work.
I'm using Play 2.1.x and I'm wondering if there is a way to encrypt passwords that might be needed for database access? I have a configuration entry that stores the database server url, user credentials for accessing the database and I do not want to leave my password as plain text. How can I have my user credentials encrypted? I want to later un-encrypt when I use them within the context of my Play server. Any pointers?
The problem is where would you store the decryption key. If you store it in the same (or similar) configuration file, the entire exercise is moot.
I am guessing that you do not want to put the plain text password in application.conf to avoid having it show up in version control system. One way of mitigating that kind of leak is to have a different store for sensitive configuration files for production systems (a different repository that has fewer accessors works nicely).
I have a problem about PDF file encryption using php.
Case: Let's say I have a local system (web based) to upload and download files, such as 4sh*red (dot) com, but it just allows PDF file. A user sign up and login to download the PDF files using his or her own personal computer. After users downloaded a PDF file from my system, the file can be viewed only on computer where they downloaded the file. But, if another user copy it (I mean: downloaded PDF file) to another computer, the file can't be viewed on that computer.
Note: I don't mean here about protecting the PDF files using password because nowadays there are a lot of softwares used to remove PDF's password protection. But, the file can't be viewed at all if copied to another computer.
Can we do that in php? If yes, do you know any algorithm to solve the case?
I really appreciate your response or answers.
Thank you.
The PDF format is an open format by Adobe. This means there are a lot of programs out there that can read it and quite same that can modify it.
If you write your own program and add some stuff to the PDF, then maybe you can do this.
Another question is - why don't you just make the document visible in the web browser to the user? Of course there's still going to be a way around for savvy users to get it, but most noobs wouldn't know how and you can easily close the simplest blocks (like right click / save).
What maybe interesting to do is what a lot of companies are doing with videos nowadays: you can dynamically add some hidden or visible 'info' to a PDF that identifies who you sent it to. In that way, if the PDF shows up somewhere else - you know who spread it.... Again - PDF is an open format, so anyone can always erase whatever you write in the main contents, so you'd have to add a hidden image to the content or something.
Hello can anyone explain me or give me some examples of how to lock a folder with VB.net.
I want to chose folder, set password for it and then lock it.
When i try to open that folder i want my app to popup asking for password, if password is ok then unlock folder if not do nothing.
I know how to do all except this autorun of my app when folder is accessed.
Thank you!
Your scheme as you described it doesn't mention encrypting files, and without encryption use of such "locking" is questionable.
Now, encryption or not, your only solution is a filesystem filter driver which will ask the password when the file is accessed, and then will allow or deny opening of the file (and on-the-fly encryption/decryption must be performed as well).
VB.NET can't be used to write a kernel-mode driver (you need deep knowledge of C and Windows internals and about 6 months of work to create a driver). You can use our CallbackFilter product, which provides a driver and lets you write business logic in user-mode.
on the Microsoft forum there is the following solution, maybe it's useful to you: http://social.microsoft.com/forums/en-US/softwareresources/thread/9a0f17af-928e-4732-a3ba-90d54ed961ea ; you may create the file they suggest dinamically by your software and then manage it.
in my Mac software I need decrypt a file and, after I do my operations on it, I will remove it. My problem is: Where can I put this file? I don't want show it to the user.
The following API will give you a directory path that is "out of the way":
NSTemporaryDirectory();
Do you mean "decrypt a file in a place the user can't access?" Any place your app can write to, the user can see. And in theory, a user can access any bit or byte on a computer to which they have physical access.
There are obfuscations and such that reduce the odds a user will come across sensitive data, but they are meant for particular situations.
Can you tell us more about your end goal here? Are you trying to implement a DRM/copy protection scheme? Are you trying to prevent cheating in a game? Do you just not trust your user? What?
I think your best bet would be to keep it in memory.
If that's not an option, it depends on what you want to do with it. It's possible you can open a temporary file, and immediately delete it - keeping the valid filehandle open, but not keeping a link to it on the disk.
Another option, perhaps - can you get your secondary program to read from STDIN or a pipe? You could then decrypt the file and pass it's content via a pipe? Clearly, the more complex this process is, the more weak links it might have, but sometimes you just have to get things working.