So I was looking at ways to lock file folders with a password in windows, and this type of security is not really supported.
Given I know C++ I was wondering if I could simply do this myself.
It would be simple enough, in the case of a text file, to copy the entire contents of the file into a C-string. I could then use basic logic to prompt for a password, if it matches, use an fstream overload and insert the whole string into a text file.
Then, simply wipe the file when I'm done using it.
I basically know how to do this, and the result would be a string containing the document compiled into a .exe which I assume would be unreadable. The thing is, I've never really studied encryption or computer security so I'm wondering how secure this would be, or if there is a better way to do this?
Could it be done on photo or video files as well, if so, how?
How hard would it be to reverse (decompile) the process?
What types of things could I do to make reversal more difficult, ie. using multiple strings, or mixing in random characters?
I'm not looking to hide super-sensitive files, I'm just curious about encryption basics.
Never implement crypto yourself - it is destined to fail. Use well reviewed libraries such as OpenSSL. A good example of using AES for file encryption: Encrypting and decrypting a small file using openssl
Using such simple approach will let you encrypt any file. And it will be secure. Why settle for weak encryption if you can have strong encryption?
If you don't want to write a program, just get, for example, OpenSSL and use the terminal: openssl des3 -salt -in file.txt -out file.des3
Related
I'm trying to encrypt and decrypt PDF file using crypto and everything works well but I need to use another library like Cryptography https://github.com/pyca/cryptography .
How I can use Cryptography library to encrypt and decrypt files like PDF file because I search a lot and I can't find one example of how I can use Cryptography with files.
Any example may help.
To answer your question Cryptography's documentation could potentially help you with this. I used the library to encrypt text files, python files, i not sure about pdf's though. But the doc's were helpful. https://cryptography.io/en/latest/
Plus this website also helped me out as well.
https://www.thepythoncode.com/article/encrypt-decrypt-files-symmetric-python
It implements the Fernet key type encryption which is symmetric encryption.
There is asymmetric encryption (I believe this type uses public and private keys) you can as far i know encrypt strings with this type of encryption. As far as encrypting files with this type of encryption i am not sure about that as i have not done any research on that my self lol!
I was messing around with some of the functions in this library and found some useful things in it. Hope this helps.
p.s. Stay away from the hazmat section of this library. ONLY use this if you really know what your doing in terms of cryptography!
I'm creating a program uysing c++ that relies off sensitive information contained within a folder located on my Ubuntu 14.04 desktop. I need some way to protect this information.
Essentially I have two buttons setup on my application. One to encrypt the folder and one to decrypt the folder. However, I have no experience with encryption and don't even know if you can encrypt a folder itself. Most tutorials I have found only talk about encrypting text. A friend recommended using AES encrytpion, but again, I can only find tutorials that show how to encrypt text.
Does anyone know of any way to protect these folders? They contain a large amount of images (.bmp and .png file types) concerning patient information along with a few text files. Obviously the quickest method would be best, as long as they aren't easily accessible without pressing the buttons.
Encryption is not some magic wand one can waive over some data, and encrypt it. If your application has a button that automatically "decrypts" the data, it means that anyone else can do it as well. For this button to work as you described, your application must logically know everything that's needed to decrypt the data. If so, a determined attacker can simply obtain a copy of your application, debug it, figure out how it decrypts the data, and game over.
At the very minimum, a passphrase will be required in order to decrypt the data; so that the application alone is not sufficient to effect encryption and decryption.
As far as the actual technology goes, the two primary software libraries on Linux that provide generic encryption facilities are OpenSSL and GnuTLS. Both provide comparable implementations of all standard symmetric and asymetric cipher-suites.
I believe that GnuTLS is a better API, and that's what I recommend. The design of GnuTLS's C API naturally lends itself to a light C++ OO wrapper facade. The GnuTLS library provides extensive documentation, so your first step is to read through the documentation; at which point you should have all sufficient information to implement encryption in your application.
Just a simple point.
You are going to have to make a blob, which you someway mount as a filesystem. You are also going to have to decide how to control access to that filesystem while people are using it. Also how people are going to synchronize access. Do it wrong and two people will write to the same area at the same time and create something that no one will ever decrypt!
Look at the source code for dm-crypt and TrueCrypt, but if you want to limit access beyond the permission system that your OS supports you may find yourself way in over your head.
you need build private filesystem,so every file operator must pass you application. you can encrypt the file contain to user.
I have encrypted a file with openssl, now I would like to read the encrypted file (actually parse that file) without decrypting it. Basically I want to see if the encrypted file contains a certain word. How can I do that? I searched different blogs and posts and the only solution I could come up with is to decrypt the file (which creates a new READABLE file), search the word in the decrypted file and then remove it. Since I don't like having to create a decrypted copy of the file and then remove it, is there any way that I can parse/read the file without decrypting it? I should probably mention that I am using c++, but I don't think it really matters, am I correct?
Thanks in advance for all the help you can give me.
There is no way to parse a file that is encrypted (at least if you are using a reasonable, not trivially breakable - pretty much everything beyond a Ceasar cipher or a XOR cipher counts as "not trivially breakable" in this context).
In other words, you will need to find a way to decrypt the content - one solution is of course to decrypt to memory, or to stdout and use a pipe to read from the file.
An example (written here as a general idea, the exact code may need some adjusting):
FILE* p = popen("openssl des3 -d -in myfile.encrypted", "r");
int ch;
while((ch = fgetc(p)) != EOF)
{
... process a character at a time ...
}
pclose(p);
I have encrypted a file with openssl, now I would like to read the encrypted file (actually parse that file) without decrypting it... to see if the encrypted file contains a certain word.
To preserve semantic security, you need to use a homomorphic encryption scheme. OpenSSL does not support those cryptosystems, so its probably not possible using OpenSSL.
If you don't care about semantic security, then you can probably use any number of schemes. Mats gave you a couple of them. But they will leak information like a sieve and are probably trivial to break with simple techniques like frequency analysis.
You might want to read up on Fully Homomorphic Encryption and Somewhat Homomorphic Encryption schemes. If the scheme is built on a lattice, then the NTRU library might offer the scheme or a useful primitive. Shoup's NTL library might also offer the scheme or primitives. (I don't know because I don't use FHE or SHE schemes).
You should also talk to the folks on security.stackexchange.com or crypto.stackexchange.com.
I'm working on a text based adventure game in C++ and I would like to store quests in a text file,but I don't want the player to read it.
Is there an easy way to encrypt it?
Another way to "hide" content of your file to player is to encrypt the file.
You can use openssl for instance.
In this thread you can have an idea on the usage.
Velthune's OpenSSL suggestion is fine but it is arguably overkill. I would try something simple like XOR encryption instead.
Of course XOR encryption is not secure, but neither is the OpenSSL approach, since your program must store the encryption key somewhere in the executable file in order to be able to do the decryption.
There is no way to truly secure the file's contents against a determined user and still have it be accessible to a program that runs on the user's machine.
So, I'd suggest XOR encryption as a simple form of obfuscation that will deter someone from changing the file casually, yet won't make your program dependent on an external library.
I have a proprietary application which uses an xml config. Currently I use boost::property_tree to read the xml file.
I would like to deploy both executable and xml file on a more public system and want to avoid anyone, including that system's administrator, from reading the xml.
Ideally, I would like to maintain the clear text xml on my system so I can easily manually modify it. Then I would call some encrypt command on the file, deploy it on the more public machine and have the executable decrypt it on the fly. I'd use the same key and just hardcode it into the source of the executable.
Is this a reasonable approach? What is the easiest way to implement this? Is there a better way?
Since you're already using boost, you could always serialize it. If you use binary archives, the file will be essentially unreadable. I guess my follow-up question would be: do you also want it to be secure? Or just unreadable?
If the code runs on the client's machine, then in principle you can never prevent the data from becoming known, because it has to be on the client's machine. You can try to obfuscate, but ultimately the client will have to be able to read the data, so it has to know it.
If you were to simply embed an encryption key in your program, the client could just scan through the file and extract the key. If you work a bit harder you can make Skype, but even that has been deconstructed.
It all depends on the seriousness of your need to protect the data. If it's absolute, then you cannot do it, but if you just want to keep the casual visitor out, you could try and make it a bit harder... tell us some details if you're serious about this.
If your goal is to prevent someone from casual inspection, then that is a reasonable approach.
If you must ensure (for some weird reason) that the configuration cannot be read, it is a foolish errand, because the program can read it, so a user who is determined to do so can do it as well. Either by disassembling the program, or simply by doing a memory dump from the debugger. Having that said, a simple, lightweight encryption will be good enough, because even the toughest encryption will be broken in the same way.
You might also consider whether using an explicitly human-readable format such as xml is well-suited if you don't want people to read it.
I had a very similar case. I used a compression algorithm to store the file 'encrypted'. zlib can be used for C++. You can easily encrypt and decrypt your file, both from command-line and from code. To add some more 'security' you can xor the compressed file with a password.
This a both simple to implement and easy to use. Of course I won't use such method if my clients are hackers, or have a financial incentive to read the XML.