From the course: Symmetric Cryptography Essential Training

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The Data Encryption Standard (DES)

The Data Encryption Standard (DES)

From the course: Symmetric Cryptography Essential Training

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The Data Encryption Standard (DES)

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- [Narrator] We're at a point now where we can actually talk about our first modern block cipher. This is the data encryption standard. Before we do that, though, we should talk about some of the goals of modern crypto systems and how the standard tried to accomplish them. The first thing that we want modern crypto systems to do is to use one key many times without compromising security. We don't want to be stuck in the position of having a one-time pad, where when we use a key, we can't use it again and have to throw it away. We also want to be able to use short keys to be able to encrypt long messages rather than having keys that are the length of the entire message, again, in one of the huge drawbacks to the one-time pad. Modern crypto systems try to meet both of these goals. One of the ways that we measure whether a crypto system has met these goals is with a strict avalanche criterion. Strict avalanche is a common consideration when block ciphers are designed. Each cipher text…

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