A runtime, architecture, and libraries for Microsoft Windows used for creating applications.

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13
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7answers
5k views

What are the realistic, and most secure crypto for Symmetric, Asymmetric, Hash, Message Authentication Code ciphers?

I'm interested in updating this two pronged question for 2011: What cryptology is most appropriate for low-powered devices (such as a cellphone), and yet still effective? What cryptology is most ...
12
votes
6answers
6k views

Is PBKDF2-based System.Cryptology.RFC2898DeriveBytes() “better” for Unicode Password hashing than traditional methods?

When is it appropriate to use RFC2898DeriveBytes versus a typical hash? Update I now understand that a KDF is typically used to create a symmetric key for possible use in encrypting a stream. I ...
11
votes
4answers
1k views

Using computer random number generators to produce keys, it is secure?

Does generating an encryption key using the random number generator on one's computer present a security risk? If so how might that risk be mitigated, specifically when generating RSA key pairs in ...
9
votes
3answers
1k views

How can I encrypt a file with .NET and have the same file size of the original file?

I'm using .NET and I've written an awesome routine (xD) that encrypts and decrypts a file using AES256 CBC. It works perfectly, but now they told me that the encrypted file must be of the same size of ...
9
votes
2answers
2k views

Data Encryption and Key Management in C#

Which route to take, what are the pros and cons, which is more secure.. Generate AES key, encrypt the data with it and then encrypt the AES key with RSA, save the encrypted data and encrypted AES ...
8
votes
4answers
2k views

What Partial Homomorphic Encryption implementations exist and how do I leverage them?

It appears that only Partial Homomorphic Encryption(P.H.E.) is practical for modern day (2011) use. However I'm having difficulty locating libraries (FOSS or otherwise) that enable me to leverage ...
8
votes
4answers
597 views

Is it safe to binary-deserialize user-provided data?

AppHarbor has a blog post containing sample C# code which reads data from an unsigned cookie and passes it through .Net binary serialization. Is that safe? Obviously, the data is completely ...
8
votes
2answers
1k views

How should an application store its credentials

When developing desktop applications, you will occasionally have to store credentials somewhere to be able to authenticate your application. An example of this is a Facebook app ID + secret, another ...
7
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1answer
598 views

A practical .NET Remoting Architecture exploit

If you were to demonstrate a .NET Remoting Architecture vulnerability with a practical attack, which one would you choose? I've read J. Forshaw's white paper on Breaking .NET Through Serialization ...
6
votes
2answers
2k views

C# Image.FromStream is that secure?

after reading the data from the request as Stream i needed to convert it to Image so i used this Method: Stream inputStream = HttpContext.Current.Request.InputStream; Image img = ...
6
votes
1answer
717 views

Secure query string parameters

I have an application which use the Thick box jQuery component to open a popup page . And I pass my parameters in query string like this : <a id="btnShowPopup6" runat="server" class="thickbox" ...
6
votes
2answers
807 views

Production ready bcrypt implementation for .NET

Which, if any, .NET / C# bcrypt implementations are considered suitable for production environments? I have seen CryptSharp and BCrypt.Net mentioned in answers to other questions but without any ...
5
votes
3answers
418 views

Why must all classes' data members be set to private?

In OO programming courses, teachers always tells us to set class members to private unless there is a good reason because it is more "secured". How does setting members to private makes the program ...
5
votes
4answers
975 views

Gold Standard for password hashing

I've developing a web application that will be dealing with highly sensitive information and I want to ensure the hashing of passwords is gold standard. Ideally I'd go for per-user salted SHA512 ...
5
votes
2answers
2k views

Reference implementation of C# password hashing and verification

Does anyone have a reference implementation (ideally 3rd party certified, or government approved) way one-way hash a password for C# and or Java? Ideally,I'd like to see something that includes a ...
5
votes
1answer
792 views

“Hello World” example of a Buffer Overflow attack in many programming languages

I'm looking for a very simple application that has an intentional Buffer Overflow embedded in it. I'm assuming this possible in systems where DEP and ASLR are not being used Ideally (and if ...
5
votes
1answer
118 views

Does every security patch get back ported to every .NET framework? Are there exceptions to the rule?

I can imagine a scenario where Microsoft will create a security patch for some versions of .NET and not others. This might occur in occasions it's too expensive to regression test and back port all ...
4
votes
2answers
1k views

How to store IV and key temporarily but securely

I am using .NET 4.0 to develop a Windows service that will temporarily store encrypted data in a database. The data will be encrypted when it is inserted, then decrypted, processed, and deleted once ...
4
votes
2answers
4k views

Diffie Hellman c# implementation

Hallo all, For a test project I have tried to implement the (famous) Diffie Hellman algorithm for safe key exchange. Now I have written this in C#: using System; using System.Collections; using ...
4
votes
4answers
4k views

Reflector - obfuscated code

I run Reflector to de-compile some program and it seems to be obfuscated. I got following output, it’s not very useful. Any ideas how to decompile obfuscated code? [CompilerGenerated] get ...
4
votes
2answers
82 views

Code-signing application from different locations

In our company, one of the software group is using a certificate from a trusted provider to sign their drivers manually on their local machine. My group wants to start to sign our installers and some ...
4
votes
2answers
217 views

Is it safe to use PBKDF2 for hashing?

I would like to get a few opinions on whether it would be safe or not to use PBKDF2 to generate a hash of a password. For my purposes I'd like to assume that the hash itself will be posted on the ...
4
votes
2answers
413 views

How to correctly implement AES in a backup application

I am writing a back-up application which should have the feature of encrypting the back-up. It must encrypt file data, paths and filenames. The application is being written in C# (.NET). Target is ...
4
votes
2answers
310 views

Is it a security risk to maintain an application developed for a version of .NET prior to 4.0?

I've had a request that we upgrade all our internally developed applications to .NET v4.0. Needless to say, this is a massive chunk of work. Is using applications based on the .NET framework prior to ...
4
votes
1answer
178 views

When does one need to be concerned with leaking timing information in .NET?

According to this post, Dominick Baier was comparing two HMACSHA256 signatures and was leaking timing information upon an unsuccessful comparison. When working with .NET crypto classes, when should ...
4
votes
1answer
640 views

Why does Bouncy Castle have a separate download for the IDEA algorithm?

I'm looking at downloading the C# binary for Bouncy Castle and see two downloads with source code. One has the IDEA algorithm, the others presumably not. http://www.bouncycastle.org/csharp/ Why ...
4
votes
1answer
89 views

Does the compiler feature of Closures decrease member variable security?

Based on this discussion, closures in C# promote private variables to public variables at compile time. Suppose a closure was implemented on a Username or Password string. Would there be any ...
4
votes
1answer
249 views

Anyone use the International Domain Name (IDN) security mitigation API's? Is there a wrapper for .NET?

The International Domain Name mitigation API's are available here for download: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=ad6158d7-ddba-416a-9109-07607425a815&displaylang=en ...
4
votes
1answer
2k views

What's the risk of changing permissions of the Security Eventlog registry key to IT operations?

Background Many developers are unnecessarily lowering the security of the event log, or requiring applications to run in Administrator mode just so they can use the event log with this C# or VB code: ...
4
votes
2answers
220 views

How do I remove or anonymize file names and path that are stored in compiled .NET exe output?

When an exception occurs in a .NET application, the exception output also includes the path and file name of the code file that resided on the developer's machine. This shares some information that ...
3
votes
2answers
2k views

Using AesCryptoServiceProvider in C#, should using an incorrect IV mangle just the first block?

This question was also asked on StackOverflow, but with no answers, and I thought this may be a better exchange, since I have the same question. ...
3
votes
3answers
1k views

Securing AES 128 encrypted ZIPs against brute force attacks

How long would it take to brute force decrypt an AES 128 encrypted zip file if the password is 8 characters long in the range of A-Z, a-z, 1-9? Does it make any difference if .NET's System.Random ...
3
votes
1answer
496 views

Hashing passwords before inserting into database

For the last 2 weeks I have been reading many blogs about website security and hashing passwords. Many sites have mentioned the pro's and cons about different ways of doing this, which has left me a ...
3
votes
3answers
947 views

AES for key encryption

Is AES a good choice for protecting a key stored on the computer of a user of my application? I have seen threads on hashing passwords that suggest using slow algorithms for defending against brute ...
3
votes
2answers
1k views

Secure communication between C# client and Java server, using certificates

I want to secure communication between simple C# WPF client and Java server. Now i have already implemented raw sockets communication, and my security is based on: server send RSA public key to ...
3
votes
1answer
3k views

How do I use C# to encrypt/decrypt data where the private key is on a smartcard, hardware security module, TPM chip etc

Is anyone aware of a C# code sample to interact with smartcard, hardware security module, TPM chips (etc), that will allow me to encrypt and decrypt data? My goal is to allow my application to ...
3
votes
1answer
701 views

Peer review of C# cryptography for Azure Table security

Edit: Update - I am researching how to implement AES with authentication in an efficient way for this project. If you have the time I'd appreciate your skill in finding the best implementation for ...
3
votes
1answer
947 views

Encrypt Medicare card numer in C# in ASP.NET

I am giving a free consultation for a non profit organisation that wants a simple system to manage multiple groups with a schedule component, etc. and also manage the medical informations of the kids. ...
3
votes
1answer
660 views

How to use DPAPI under load balance environment

DPAPI can be used to encrypt the secret data. We intend to use it in our web app to encrypt some data and store the encrypted data in database. When needed we decrypt the data and present them on ...
3
votes
1answer
2k views

Is PBKDF2 only SHA1 in C#?

I can't find a way of specifying the hashing algorithm used by the PBKDF2 (the Rfc2898DeriveBytes class) implementation in C# System.Security.Cryptography. It seems to be just SHA1. Am I missing ...
3
votes
1answer
735 views

Using GPG or PGP for symmetric database encryption/decryption in c#

I am looking to symmetrically encrypt/decrypt information in a database. This info consists of short pieces of information, which need to be individually encrypted when a specific method is called. I ...
3
votes
1answer
255 views

A simple example for showing the use of Data Execution Prevention (DEP) security feature

I am finding it really hard to figure out why we need a DEP! Microsoft states this about DEP: The primary benefit of DEP is to help prevent code execution from data pages. Typically, code ...
3
votes
1answer
304 views

Does strong naming remove the need for packing/obfuscation?

I'm new to .NET programming, and I'm wondering - from a security perspective - whether the strong naming scheme used in .NET assemblies completely removes the need for other commonly used techniques ...
3
votes
1answer
55 views

How to minimize security risk when having to work with decrypted (plain text) passwords due to 3rd party API design

I'm developing an application (C#) for Microsoft SharePoint platform that uses SQL Server's (2008 R2) Remote BLOB Storage (RBS) technology. To accomplish certain client-side tasks, I must obtain ...
2
votes
1answer
99 views

Using MySQL in .NET and other easily-decompiled languages?

How would people use MySQL in C#, or really any other managed application? Couldn't someone simply decompile the application and find out the password/etc. for the database?
2
votes
2answers
248 views

Are GUID visible when compiling a .NET project?

I know if a person has a GUID from a machine that person can figure out if other guid belongs to that machine. In a .NET project (csproj and the visual studions solution file) GUIDs are generated. If ...
2
votes
3answers
723 views

How to do a virus scan before post attachments in asp.net application

How to do a virus scan before post attachments in asp.net application,when they find a virus on to give up post attachments,otherwise proceed to upload. I wonder if there are any APIs out there where ...
2
votes
2answers
187 views

Security concerns with a “fiddle” site?

I recently came across a cool site for testing .NET code (http://dotnetfiddle.net/). In the FAQs they mention that they have two restrictions for security purposes: No access to File System IO No ...
2
votes
3answers
130 views

Identifying and preventing execution of “any” function via Late-Bound commands

The Command Pattern is widely used to create a robust, salable applications. However I see guidance in this MSDN article that could allow a caller to invoke a late-bound command... enabling the ...
2
votes
2answers
112 views

Keyed-hashing a password with a hash of the password + salt as the key, is it safe?

I was looking at our authentication system which hashes passwords differently than I was taught. The salt is a constant byte array and it uses the password + the salt as a key for the password hashing ...