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September 2006 - Posts

Friday, September 29, 2006 5:00 AM

ROT 128 Stream Upgrade Sample, Part 3

Last time, we built the binding element for the stream upgrade sample . The job of the binding element was to stash itself away in the binding context so that the transport could later pull out the stream upgrade and build the provider. This time we'll
Posted by Nicholas Allen | 4 Comments
Attachment(s): AsyncResult.cs
Thursday, September 28, 2006 5:00 AM

ROT 128 Stream Upgrade Sample, Part 2

Building a stream upgrade for ROT 128 starts with creating a binding element to put in the channel stack. This binding element extends the special StreamUpgradeBindingElement base class , which functions very similarly to the specialized binding element
Posted by Nicholas Allen | 5 Comments
Wednesday, September 27, 2006 5:00 AM

ROT 128 Stream Upgrade Sample, Part 1

The mission for the next five days is to build and demonstrate an implementation of a stream upgrade. For review, a stream upgrade is a component that plugs into the transport and rewrites the byte stream as it goes on and off of the network. Stream upgrades
Posted by Nicholas Allen | 7 Comments
Tuesday, September 26, 2006 5:00 AM

September CTP Released

Windows Vista released an interim build over the weekend to let customers track the bug fixes made after RC1. The corresponding version of WCF for this release is being called the September CTP. If you've just installed RC1, then it's probably not a high
Posted by Nicholas Allen | 0 Comments
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Tuesday, September 26, 2006 5:00 AM

Reader Survey Outcomes

As expected, the Monday post did not happen due to the server maintenance running a few hours long and clobbering the window for queuing the post. Unfortunately, the maintenance was for upgrading the Community Server version and that failed, so there's
Posted by Nicholas Allen | 0 Comments
Friday, September 22, 2006 5:00 AM

Math Behind the RSA Algorithm

This post is to tie up some loose ends in regards to actually performing the RSA computations. I've avoided including too much math in the earlier posts to make them easier to read. Here are some references that help explain the individual steps. The
Posted by Nicholas Allen | 2 Comments
Friday, September 22, 2006 5:00 AM

Potentially No Post Monday

There is some server maintenance scheduled for Sunday night, which may interfere with the normal early Monday morning blog post. I had the reader survey results and the first part of the stream upgrade sample planned for Monday. Those may happen Tuesday
Posted by Nicholas Allen | 0 Comments
Thursday, September 21, 2006 5:00 AM

A More Recent RSA Attack

One of the interesting things about writing articles ahead of time is that the plan sometimes changes when it's time to publish the articles. It turns out that in the last few weeks someone has found an interesting forgery attack on RSA signatures . This
Posted by Nicholas Allen | 3 Comments
Wednesday, September 20, 2006 5:00 AM

Reminder: 2006 Reader Survey

If you haven't taken the time to complete the reader survey , please help out by doing that this week. I've already gotten some cool ideas from the feedback and it's to your advantage to tell me what you like and don't like. The incoming rate has started
Posted by Nicholas Allen | 0 Comments
Wednesday, September 20, 2006 5:00 AM

Attacks on RSA

RSA has several weaknesses called protocol failures. Protocol failures are not actually an exploit in the RSA algorithm. Instead, a protocol failure occurs when you perform inadvisable actions that give the attacker more information than they would otherwise
Posted by Nicholas Allen | 5 Comments
Tuesday, September 19, 2006 5:00 AM

Using RSA for Signing Messages

A nice property of RSA is that if we swap the role of the encryption and decryption keys, it's still possible to transmit messages . That's because the computation (M e ) d mod n is the same as (M d ) e mod n. Typically, messages are encrypted with your
Posted by Nicholas Allen | 6 Comments
Monday, September 18, 2006 5:00 AM

2006 Reader Survey

As promised, today I'm putting out a survey to collect some of your feedback about the last six months of blogging. I decided to not go with a site like SurveyMonkey to let you be more freeform about your responses. Answer as many of the questions as
Posted by Nicholas Allen | 2 Comments
Monday, September 18, 2006 5:00 AM

Splitting Messages for RSA

For your particular pair of RSA primes, there is a fixed size to the messages that can be encrypted with the product, n, of those primes. During decryption, you will always end up with the smallest positive integer message that satisfies the algorithm.
Posted by Nicholas Allen | 7 Comments
Friday, September 15, 2006 5:00 AM

No Real Post Today

I was going to post a survey today to collect some reader feedback, but I decided it would be better to make it a larger production and give people all next week to send in responses. The normal posting schedule will still take place. That means you'll
Posted by Nicholas Allen | 0 Comments
Thursday, September 14, 2006 5:00 AM

Using RSA for Sending Messages

One of the key points made about the Diffie-Hellman algorithm is that it doesn't actually allow you to send a message from one party to another. DH is useful for constructing a new shared secret value but can't directly be used to exchange an existing
Posted by Nicholas Allen | 4 Comments
Wednesday, September 13, 2006 5:00 AM

Attacks on Diffie-Hellman

We're going to continue looking at the Diffie-Hellman algorithm today by examining how to configure the algorithm to be more resistant to attacks. DH is small enough that I'm not going to summarize the algorithm here. You can go back to the description
Posted by Nicholas Allen | 3 Comments
Tuesday, September 12, 2006 5:00 AM

Diffie-Hellman Key Exchange

If you've been reading the previous posts on network security , then you've seen several instances where two parties need a shared secret. We've just been assuming that a shared secret is magically known. How can two parties share a secret without having
Posted by Nicholas Allen | 10 Comments
Monday, September 11, 2006 5:00 AM

Stream Upgrades, Part 3

Today's the final part of the series on the stream upgrade model ( StreamUpgradeBindingElement and StreamUpgradeProvider were covered previously). I've got a sample of a stream upgrade to show next week but I figured that everyone would like a little
Posted by Nicholas Allen | 3 Comments
Friday, September 08, 2006 5:00 AM

Stream Upgrades, Part 2

The stream upgrade model consists of four abstract base classes. We looked at the StreamUpgradeBindingElement yesterday. Since stream upgrades don't have a corresponding channel, the only purpose of the binding element is to notify the transport that
Posted by Nicholas Allen | 5 Comments
Thursday, September 07, 2006 5:00 AM

Stream Upgrades, Part 1

The next several posts are about the stream upgrade model for modifying the byte stream output of a transport. I'll use these posts to cover the basic elements of the stream upgrade model, take a break for a while to talk about some other topics, and
Posted by Nicholas Allen | 7 Comments
Wednesday, September 06, 2006 5:00 AM

You Must Understand This

WCF allows you to customize the collection of message headers sent with a request, including defining your own custom headers. Message receivers tend to be very loose about the messages that they accept and they typically will silently ignore any headers
Posted by Nicholas Allen | 1 Comments
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Tuesday, September 05, 2006 5:00 AM

Building a Composite Duplex Binding Element

I occasionally get requests to help people build what turns out to be a variation of our CompositeDuplexBindingElement . Composite duplex is just a channel shape changer that supports both reading and writing, and has independence between the connections
Posted by Nicholas Allen | 1 Comments
Friday, September 01, 2006 3:25 PM

Hey Look! WCF RC1 is Done

The RC1 release of WCF is done and only very shortly after the end of August . There are very few new features or compatibility breaking changes in this release. The big differences you should notice are improvements to the reliability and performance
Posted by Nicholas Allen | 3 Comments
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Friday, September 01, 2006 5:00 AM

Finding Your Upgrade Path

One day, the official first version of WCF will be completed and released. Lots of people are not just waiting around for that day to come and have already built lots and lots of applications on top of prerelease versions of WCF. Everyone will want to
Posted by Nicholas Allen | 1 Comments
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