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

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14
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7answers
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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
8k 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 ...
12
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2answers
3k 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 ...
11
votes
4answers
2k 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 ...
10
votes
3answers
2k 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
5answers
2k 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 ...
9
votes
4answers
993 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 ...
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
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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
1answer
66 views

Is Rfc2898DeriveBytes using HMAC SHA1 still considered “secure enough” for hashing passwords?

I've been told by a CISSP that the .NET class Rfc2898DeriveBytes would not pass a security audit today because it still uses SHA1. It's reliance on SHA1 - even with the iterations - leaves it too ...
7
votes
3answers
903 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 ...
7
votes
1answer
963 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
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3answers
4k views

How can I detect a VPN connection (even just in some cases) to get the real location of the user

I'm creating a web site, I would like to allow people to sign-up only from their "real" physical location (not using a VPN). I was thinking maybe comparing local and server time... what else...? ...
6
votes
2answers
2k 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 ...
6
votes
2answers
743 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 ...
6
votes
2answers
3k 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
960 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
1k 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 ...
6
votes
1answer
76 views

Is there any reason to use AesManaged over DPAPI in this scenario?

I have a situation where my web application is going to be deployed on multiple web servers, and I'll be wanting to store some securely encrypted data on the DB servers (each web server has a DB ...
5
votes
2answers
3k 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 ...
5
votes
1answer
63 views

ECDH BouncyCastle KeyAgreement length

I am attempting to obtain a shared secret using BouncyCastle's ECDH methods in C#, however I am receiving a shared key which is much shorter than the 48 bytes I expect it to be. I have a trusted ...
5
votes
1answer
2k 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
2answers
3k 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
1k 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 ...
5
votes
1answer
156 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 ...
5
votes
1answer
4k 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: ...
5
votes
1answer
5k 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 ...
4
votes
2answers
5k 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
7k 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
7k 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. ...
4
votes
2answers
100 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
845 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
3answers
2k 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 ...
4
votes
2answers
331 views

How to bypass .Net 4.5 request validation, for an XSS attack?

.Net has a feature called request validation which detects malicious inputs and blocks the request. By its nature, request validation is not a precise science. OWASP clearly recommend to only rely on ...
4
votes
2answers
2k views

Best place to store authentication tokens client side

When my users are authenticated they receive an authentication token, I need to use this authentication token to authorize some asp.net WebAPI calls. To do this I need to add the token to the head of ...
4
votes
1answer
584 views

Encrypting/decrypting our license key

We need to provide a license key to customers for our application. The actual license is XML but we need to encrypt it and then in our program decrypt it. I think it is the following, but am asking to ...
4
votes
1answer
207 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
745 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
93 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
67 views

Is the ProtectedData class still an acceptable method to store passwords?

I'm writing a piece of software which will have to store a users password to allow authentication with a 3rd Party service. Unfortunately, this service currently requires the use of a password rather ...
4
votes
1answer
400 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 ...
4
votes
1answer
1k 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. ...
4
votes
1answer
311 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
297 views

OAuth2 - Is it safe to return the access-token to the user?

I'm new to OAuth (1 & 2), and I'm developing the server side of a mobile app that has a form with a "Fill Details from Google account" button. I don't need any long-range ...
4
votes
2answers
350 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
4answers
5k views

What Are The Best Practices (Application Security Policy) For Modifying Rijndael Salt, IV, Pass Phrase

(Note: originally posted in SO - advised to post on SSE) With regards to Rijndael encryption, what (if any) are the best practices (and consequences) regarding the periodic modification of one or ...
3
votes
1answer
1k 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
220 views

What are the (practical) dangers of writing your own login method?

I have always been told that writing your own login method (e.g. validate user given the username and password) is bad practice, and that one should reuse existing libraries for that. I have always ...
3
votes
3answers
1k 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
2k 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 ...