Category Archives: cryptography

Generate a random password in C#

As I mentioned in a recent post, you should always use a strong password for every login. Remember, a computer can perform millions or billions of operations per second, so your daughter’s birthday or the name of your son’s guinea … Continue reading

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Why Twitter recently wanted you to change your password

A few days ago, Twitter asked all of its users to change their passwords. The reason they did that was that they found a bug in their system that made an internal log file store passwords in an unencrypted form. … Continue reading

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Make the user enter a password to use a program in C#

The example Display a simple password dialog before a program starts in C# displays a simple password form. It compares the value entered by the user with a string inside the program to decide whether the user entered the right … Continue reading

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Find duplicate files in C#, Part 4 of 4

The last three posts described an application that searches for duplicate files and removes them. The program seems to work fairly well, at least for small test directories. When I tried it on a directory containing around 8,000 files, however, … Continue reading

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Find duplicate files in C#, Part 3 of 4

The last two posts described an application that searches for duplicate files and removes them. This post explains how the program removes the files when you click the Delete Selected button. When you click the button, the following code executes. … Continue reading

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Find duplicate files in C#, Part 2 of 4

The previous post Find duplicate files in C#, Part 1 of 4 explained how the example uses a LINQ query to select files grouped by hash code. This post explains how the program displays the files’ contents and how the … Continue reading

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Find duplicate files in C#, Part 1 of 4

This example lets you find and remove duplicate files. It’s fairly complex, so I’m going to cover it’s more interesting pieces in several posts. I won’t cover some of the less interesting pieces at all. Enter a directory path or … Continue reading

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Calculate hash codes for a file in C#

Hash codes are codes that concisely represent files or other chunks of data. The basic idea is to combine the data’s bytes in ways so that two different files are likely to have different hash codes. If you save a … Continue reading

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Use steganography to hide one large picture inside another in C#

The example Use steganography to hide one picture inside another in C# explains how you can hide one image inside another. This example uses the same tools to hide a large image inside another large image so you can get … Continue reading

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Use steganography to hide one picture inside another in C#

The example Use steganography to hide messages in an image in C# hides message bits in the least-significant color bits of randomly selected pixels within an image. The idea is that small changes to the least significant bits of a … Continue reading

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