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Id like to encrypt a file and share it. I'd like the file to be decrypted just one time. I was wondering if there are security or encryption protocols that can be used to implement a 1 time use scenario. In simple terms the decryption key would only be good one time.
No it's not possible, with any kind of computer and any kind of OS.
What you want is called a DRM, and your file would need to be read by a program you've coded that would destroy the file (and the decoding key) after reading. But in order to protect the decyphering program from being copied, you'd have to sign the application against your OS, and make your OS protect that file from deletion. And in order to protect your OS from being copied with the file within, you'd have to use a computer that has a chip in the CPU making everything uncopiable... That's called trusted computing.
And though it may theoretically work, it would still be possible to keep a copy of your file, and use a super computer for up to 1000 years (or one hour, depending on your algorithm and the size of your key) to find your decription key, and thus access your precious content.
For the story, sony has tried putting DRMs in their CDs, and that's what they end up creating.
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I am new to reverse engineering.
I am using immunity debugger, x64 dbg, ollydbg.
Softwares like Winzip we can't able to read it's strings because it is obfuscated (encrypted).
I have watched some tutorials on YouTube, but those softwares ( power iso) strings were unencrypted.
I need to know is there any way to deobfuscate (decrypt), it's strings to reverse engineer
Obfuscation should not be confused with Encryption, semantics aside, Encryption is strong protection against capable attackers, Obfuscation is not.
With regard to your question, the theoretical approach is:
Identify cryptographic primitive being employed
Identify mode of operation, cryptographic trap-door function
Execute best known attack on cipher-text
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I recovered a deleted text file from a bitlocker encrypted drive using "EaseUS Data Recovery" tool. The recovered file seems to be the raw encrypted bits. Is there a way to decrypt that file since i have the bitlocker password and recovery key? I am aware that you can decrypt a whole drive, but that is not going to work. I just need a way to decrypt that one file.
I doubt it is possible. The real encryption key is stored on the harddisk; the bitlocker password (or recovery key) only give you access to use that key for decrypting. That real key (which you would need) is never visible / accessible outside the hard disk controller and its memory.
You can verify that by changing your bitlocker password - it takes only milliseconds, because it only is hashed and written onto the hard disk; the encrypted files themselves are never touched, as they still use the same old key.
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I am looking to provide some properiatary software with the raspberry pi as the platform (but this could be with any embedded board). I'm looking for a way for the file system to only be visible on that device.
Is this possible? How?
You could encrypt the whole disk or the volume using LUKS or dm-crypt if your distribution supports it. It's also possible to encrypt files or directories on the disk while leaving the file-system mountable (but scrambled). If you go the latter route, it would be a good coding experience to write your own software that encrypts files and then de-crypts them when a key is entered.
Either way, you'll run into an issue: Before using the clear data, someone has to input the key. If the key is stored on the card, nothing prevents an attacker reading the key from a stolen card. If it's input by a person, that person needs to manually enter the key after every boot.
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I will be moving a high load prod system over to new hardware over the next few weeks. However in the mean time I would like to validate that the new hardware will handle the expected loads. I would really like to stick some kind of 'proxy' infront of the current web server and copy all that http traffic to the new environment, i.e. run them both in parallel.
Ideally this proxy would also validate that the responses are the same.
I can then monitor the new hardware stats (cpu, mem, etc) and see if it looks ok.
What is this kind of proxy called? Any one have any suggestions? This is for a Windows .Net (asp.net) and SQL server environment.
Thanks all
Varnish comes to mind - https://www.varnish-cache.org/
Edit
I'd actually use nginx... (two years experience after answering this question).. varnish would be silly to use. nginx would definitely be the better option.
Have a look a JMeter. It's Java based but allows you to record user journeys and play them back in bulk for stress testing.
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I was wondering where I could learn more about decentralized sharing and P2P networks. Ideally, I'd like to create something to help students share files with one another over their universities network, so they could share without fear of outside entities.
I'm not trying to build the next Napster here, just wondering if this idea is feasible. Are there any open source P2P networks out there that could be tweaked to do what I want?
Basically you need a server (well, you don't NEED a server, but it would make it much simplier) that would store user IPs between other things like file hash lists, etc.
That server can be in any enviroinment you want (which is very comfortable).
Then, each client connects to the server (it should have a dns, it can be a free one, I've used no-ip.com once) and sends basic information first (such as its IP, and a file hash list), then sends something every now and then (say each 5 minutes or less) to report that it's still reachable.
When a client searchs files/users, it just asks the server.
This is a centralized network, but the file sharing would be done in p2p client-to-client connections.
The reason to do it like this is that you can't know an IP to connect to without some reference.
Just to clear this server thing up:
- Torrents use trackers.
- eMule's ED2K uses lugdunum servers.
- eMule's "true p2p" Kademlia uses known nodes (clients) (most of the time taken from servers like this).
Tribler is what you are looking for!
It's a fully decentralized BitTorrent Client from the Delft University of Technology. It's Open Source and written in Python, so also a great starting point to learn.
Use DC++
What is wrong with Bit-Torrent?
Edit: There is also a pre-built P2P network on Microsoft operating systems that is pretty cool as the basis to build something. http://technet.microsoft.com/en-us/network/bb545868.aspx