encryption

How to secure ebooks?

If I want to sell my ebook online, and want to make sure the buyer can not redistribute my ebook, how can I secure it? ...

Decrypting iPhone encrypted sting in .Net app

I am encrypting via the NSData AES128EncryptWithKey method and having problems decrypting it on the .Net side. I've read several posts that basically all say that my Salt and / or Initialization Vectors must be different and I suspect that my problem is related to that fact. However, I cannot find anything that says what the Salt used ...

Problem in code with File Descriptors. C (Linux)

I've written code that should ideally take in data from one document, encrypt it and save it in another document. But when I try executing the code it does not put the encrypted data in the new file. It just leaves it blank. Someone please spot what's missing in the code. I tried but I couldn't figure it out. I think there is something...

Security question: authentication vs authorization ?

Let's assume I must have user's sensitive data that was optionally encoded on the client side. Encryption (optional) should be done with user's passphrase. User login (optional) should be done with user's password. Notes: plain-text password is not stored on the server or transfered over the network. My options and their drawbacks:...

Home-Made Cryptography

I know you should never make your own cryptography, whether it is a cipher or hashing algorithm or even a secure pseudo random number generator these things I developed over a long standardisation process. However what I'm looking for quotes or good point in order to quickly describe/argue this to the occasional developer that decides to...

How to generate secure passwords for new users?

I have a list of students that are being added via a form inside the admin area. I'm trying to come up with a password generating solution for each addition that will be both secure and viewable from the admin panel (like below). I need it to be viewable so that the admin will be able to print out the passwords and hand them out to th...

Problem implemeting RC4 with IV in C++

I have recently stumbled upon the CipherSaber project, and thought it would be fun to implement the CS1 algorithm, an RC4 with IV. On encryption it generates a random 10 byte IV, it appens it to the password and then crypts. On generation the IV is read from the beginning of the file (first 10 bytes) and then appended to the password and...

Java/Scala bi-directional MD5

Hello, I am trying to find some samples of how to take a string and hash it using MD5, and then be able to reverse hash (correct term?) back to the original string. Does anyone know of any documentation that shows how this can be done, or ideally has any sample code they could share? I've read about the java.security.MessageDisgest cl...

Does encryption guarantee integrity ?

To build a secure system can we assume my question before starting programming. Both in symmetric and public-key encryption, is my question well-proofed ? If no, what are the vulnerabilities, can you give an example? ...

C++ free encryption libraries

So far I've come across Botan and Crypto++ which both provide reversible (e.g AES) and non-reversible (e.g SHA) encryption. I wondered if anyone can recommend either, or something else? ...

NHibernate and SQL Server 2008 encryption

How to perform SQL Server built-in encryption/decryption with NHibernate? I mean encryption of separate columns. ...

Using pen strokes with fuzzy tolerance algorithm as encryption key

How can I encrypt/decrypt with fuzzy tolerance? I want to be able to use a Stroke on an InkCanvas as key for my encryption but when decrypting again the user should not have to draw the exact same symbol, only similar. Can this be done in .NET C#? --- Update (9 sep) --- What I ideally want is an encryption algorithm that would accept ...

SQL & ColdFusion Encryption

Hi, I know how to encrypt data using ColdFusion using AES_128. I also know how to encrypt data using MSSQL AES_128. Does anyone know if it’s possible to encrypt data in ColdFusion using AES_128, then decrypt the string in MSSQL? I’ve played around with it a lot and can’t seem to figure it out. Thanks, Paul ...

CF DESEDE encrypt() Key Length Issue

I am trying to encrypt a string using ColdFusion encrypt() with a 3rd party provided key like this: encrypteded = encrypt('theString', 'FD52250E230D1CDFD5C2DF0D57E3E0FEFD52250E230D1CDF', 'DESEDE/CBC/NoPadding', 'BASE64', ToBase64('0')); I get: "The key specified is not a valid key for this encryption: Wrong key algorithm, expected...

How secure is 64-bit RC2?

In encryption, would two symmetric algorithms be considered to be equal in terms of security if their key sizes are equivalent? (i.e. does a 64-bit RC2 algorithm provide the same exact security that a 64-bit AES algorithm would?) How secure (or insecure) would it be to use a 64-bit RC2 algorithm? How long could I expect it to take for ...

C# Private/Public Encryption using AES

I am trying to figure out how to make public/private keys that are AES encrypted. I'd like to be able to use it like so: byte[] BytesToEncrypt = { 0x01, 0x02, 0x03, 0x04, 0x05 }; byte[] PublicKey; byte[] PrivateKey; byte[] EncryptedBytes; byte[] UnencryptedBytes; PrivateKey = CreatePrivateKey(); PublicKey = CreatePublicKey(PrivateKey);...

how to check whether the data is tamper or not while the form is POST in asp.net

I have a form that submits the game score. Is there any way to check whether that game score is not tampered during submission. I am using POST method, for GET method we can use HASH, but i am looking for POST method ...

Require authentication through https with spring security?

I'm using tomcat 6, spring mvc 3.0.0 and spring security 3.0.0, and since the passwords I store in the database are sha1 hashed, I can't use digest authentication (section 9.2.1 of the documentation spells that out). For this reason, I need to make authentication happen through https. Due to potential processing overhead, I want to keep...

Java API for encrypting / decrypting pdf files

Hello, I need to encrypt and decrypt pdf files. Is there a free or low cost Java API that does that ? Basically I need to hide files from normal users. Any other suggestion on achieving that programatically ? Thanks, Deep ...

Encrypted viewstate causes search to break in WSS 3.0

After setting the web.config attribute viewStateEncryptionMode to "Always", the following error is thrown when attempting to search using the standard search textbox: Unable to validate data. at System.Web.Configuration.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, IVTyp...