i developed a very simple vb.net application and i need a way for every user to verify that they have paid for it. i would like the simplest method possible. it will be an off-line registration. I am actually looking for a way that I can program this easily myself, and am not interested in third part solutions.
Just ask for the name, and calculate a hash (such as SHA1 or MD5) for that name (maybe lowercase and strip whitespace first), prefixed with some secret text that is hardcoded in your program. If you want different keys for different versions, then also prefix the version number before calculating the hash. That hash will be your registration key (or, if you think it is too long: take the first characters of the hash).
Have the user enter both the name and the registration key, and store those in the program's configuration. Then recalculate the hash in exactly the same way whenever you need to validate it, and compare it to the stored key.
You could store an encrypted string in the user's registry (e.g. his Full name). Decrypt that string at application start to check if the license is valid.
How secure do you want it to be?
If you're looking for rock-solid piracy protection (if it even exists) you'll have to combine it with some sort of online registration/activation system. Or use a 3rd party solution as opted by Mitch Wheat.
Related
I'm looking for a tool or method to prove the authenticity of resources download from the web and stored locally. To be clear: I don't mean the SHA or MD5 checksums to verify a downloaded file. What I need is a way to download and store a web resource in such a way that I can later prove that said resource indeed originated from that web server.
In particular for the following scenario: A website published an article about a client. He would like to sue for defamation of character. I need a way to store the article without them having the possibility of simply removing it and denying they ever published it. So preferably this would be a tool that is backed by publications making it credible in court.
I have thought about storing the TLS certificate, keys and the encrypted data. That would rely on the root CA, but I think that would in itself not be a problem. I could do this using a custom program and a library like OpenSSL, but I think this is such a common problem, there probably is a relatively standard tool for it. Also, I am not entirely sure to what extent this would constitute reliable evidence. And can someone point to publications that would back this method?
Maybe I am using the wrong search terms, but everything I find is about aforementioned SHA or MD5 checksums. Any help is much appreciated.
If I understand correctly you need something like signature with timestamp. Yes?
You not only need checksum from document (article, text value, whatever) but also proof that this article really existed in time.
When using digital signature you can store such timestamp in 3rd party certified providers. You sign document and send checksum to 3rd party provider. Later you can ask provider to verify that this exact document is valid & was indeed created at given time.
https://en.wikipedia.org/wiki/Trusted_timestamping
As this can cost (fee for provider to store the timestamps) you can create checksums from many documents (like take all documents from one hour), store all of them in a single file, create checksum from that file and sign it with timestamp. This way you create one timestamp for documents batch, not for each document.
I working on a simple vb application. But I want to protect it to give the user the option to use it only for a specific time.
So I was thinking to make a text file with a key-code (Beside Random characters, it contains an expire date). When the application is started after this expire date, the application should close automatically.
The location where this textile is location can be the same location where the executable is running from.
Does somebody of you have a good idea how to implement it? Or is there a easier way how to implement this
If you want to give a "Trial period" to your application you might want rather hard-code that to prevent tampering. Then, when purchased make a modification to registry and different files (maybe downloads a few files that "register" the application so that it recognizes itself as "full". To go one step further maybe periodically have the application reach out to your server and verify the license.
This is a huge subject that a lot of smarter people than me can weigh in on. I will note that this is part of a constant battle between developers and hackers trying to get around licensure.
To make software unlocked for some period of time, you can create text file on websites like Pastebin and add them an expiry date. Then make your software check if file is still valid.
Note that users can "track down" requests your software sends, never store your private information linked with your software.
You can also use HWID protection which ensures your software will work only if it matches hardware information stored in encrypted string.
You can hash other user's information like username, wifi name and so on, but remember that changing any of this information (OS, hardware or system information) will create new unique HWID, which may not match the previous one - resulting in failed HWID authorization.
To make bypassing protection harder, you can obfuscate your software.
Let me first say that I'm doing nothing illegal. I'm doing this for learning purposes only. Using my own virtual network.
So I am trying to SSH into a server and say I know there is a user called urbasnlug so ssh urbanslug#ipadress but I need the root passoword.
I have a wordlist that contained only strings without alphanumeric strings. How would I use this wordlist to crack a password that has an alphanumeric password which is of mixed cases but the number in the password never goes past 100
Say the wordlist had the strings:
pass
word
How could I use these list to crack a password such as PaSSword99.
Maybe in ways other than with the use of word lists.
If you can't help me at least tell me why you can't.
I can write a C or Python module to do this but I know that there has to be something out there that already exists.
So you have two things to achieve here. The first is generating the set of passwords you wish to try. The second is throwing that list of passwords against your server.
The first problem is a classic use case of John The Ripper, you can have it read in your wordlist, apply some mangling rules (such as appending 0-99 to each word, permuting cases etc), and output a final, complete password list.
The second problem is quite easy to solve once you have the password list. You could just loop over the passwords in bash, but if you're really lazy, Metasploit has an SSH scanner that reads a password list for you.
Of course, breaking this down into two stages means you are storing the huge password list as a file. In general you would be more likely to pipe the output from John The Ripper to your SSH scanner, rather than using an intermediate file.
First off it will be difficult to get the root password if you are only logged in as a normal user. However, there are different ways of getting 'root' which I believe go beyond the scope of this forum.
Nonetheless, I don't get the correlation of where you wordlist comes to play if already know the characters present in the root password;which would mean you have the root password anyway.
Try and use Hashcat to try and retrieve password. You however need a wordlist eg rockyou.txt or any of those available in the OpenWall site (makers of John the Ripper, which is another tool which is only as good as your wordlist.
i think it will be easier (faster?) to get root via a local exploit, read /etc/shadows and crack that password
In my program, I have a simple login prompt so that only certain users may enter a program, as well as make the program function differently depending on the user. What I would like to do is have the information for the user login information (username, password, etc.) securely stored without going through an online database. I know that using a text file to store this information is a very bad idea, and I'm sure there is an easier way to do this than to make an array of this login information internally inside my program. Could you all give me some suggestions of a way to do this?
Hashes are what you need. Paste a hash-making function into your code, MD5 functions are available online for all major platforms. Then store your pairs of hashes in your config file. Devise a clever way to combine a password with your admittance options into another hash so that the file is edit-proof. This way, you can distribute the account configuration and if you don't make a trivial cryptographic mistake, it will work just as you want.
Example of the config file line (hashes truncated to 6 chars for clarity):
1a2b3c print;search;evaluate 4d5e6f
Here, 1a2b3c is obtained as MD5(username.Text+verysecret), the verbs are the account's rights and 4d5e6f is obtained as MD5(line[1]+verysecret+password.Text) where line[1] is the split result of the config line where the verbs are stored and the rest is the user's password.
Note how the password gets automatically salted by the verbs and how the verbs are protected against editing because that would invalidate the password hash. The verysecret constant is something hidden in your executable code that will prevent anybody from computing the hashes and unlocking the program.
Hashing is not an asymmetric cipher or key pair; a motivated attacker can crack your program to bypass protection altogether anyway, so going to further lengths is useless.
If you are cheap to find an asymmetric scheme, but cunning enough, you can change a few initialization constants in that MD5 function. This will make the cracking of your code harder, especially against the making of a counterfeit account file.
EDIT: When authenticating, don't just if(hashfromconfig == computedhash)... Script kiddies know how to hook into the string comparison function. Write if(MD5(hashfromconfig) == MD5(computedhash))... instead... Then the string comparison will work just as before, only it will not see your precious key hash that goes into a wannabe-counterfeit file. Ideally, have several versions of the MD5 function scattered across your code and named differently. Use if(foo(hashfromconfig) == bar(computedhash))... for a nice effect.
"without going through an online database." - do you mean on the client side?
"securely stored" and "client side" are pretty much mutually exclusive terms in this scenario.
There is absolutely no way to securely store data without touching online (server-side) source of some kind. If you are touching server-side source, it might as well be a DB.
select HASHBYTES('sha','what is it')
Result --0x2327A09C2FDAD132E436B5CC12E9D5D283B5BA69
is it possible to convert back hashbytes to string '0x2327A09C2FDAD132E436B5CC12E9D5D283B5BA69' as a input
want to get out put as 'what is it'?
Absolutely not. A hash is, by definition, one way.
What you're looking for is encryption, which you can do using the EncryptByCert and DecryptByCert functions, explained in detail here.
No. That's the whole point of a hash.
You use them for something like a password, such that every time someone tries to log in you compute the hash of the password they tried to log in with (plus a salt) and compare that with your stored value. This way even if someone (like a disgruntled employee) finds a backup tape for the database where your passwords are stored and an encryption key, they still wouldn't be able to log into your system and act on live data.
A hash function is defined as "one way" meaning that you convert text into a digest (the result you see above). If you are using this for password encryption the accepted usage would be to run a users input (from their password form) through the hash function and verify that it matches the stored digest.
If you wish to have decryption of a provided text input you will want to look into other cryptographic solutions such as Symmetric-key or Asymmetric-key algorithms.
Of course if you are doing any of this you are going to want to sanitize your input.
Hashing as the previous posters mentioned, is definitely a one way operation. It takes a (potentially large) input, and processes the input quickly in such a way that the output is a small but very unique (based upon input) output. Both by design and by nature of having a small sized output, a hash cannot be undone as the original input has been lost in the conversion. Common hashing algorithms include the Message Digest family (usually MD5) and the SHA family you mentioned in your question.
Again as the previous poster mentioned, if you're looking for a 2-way operation, encryption is what you are looking for. Further more, if you want the same user to both encrypt and decrypt a string, stick with symmetric encryption. Some common algorithms used in practice today are AES, DES, and Blowfish.
If you have a minimal perfect hash then at the very least you should be able to brute force the original input. But presumably this is not what you're asking about, if that is right then see all of the other answers :)