From the course: Symmetric Cryptography Essential Training
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Introduction to block cipher modes
From the course: Symmetric Cryptography Essential Training
Introduction to block cipher modes
- [Instructor] By now, we've seen a few examples of real world block ciphers, but an important question remains. Since a block cipher can only operate on one block at a time, what is the best way to encrypt more than one block? We start with the mode called electronic code book mode. And it's called electronic code book because it's almost like the plaintext blocks are looked up in a code book to find their corresponding ciphertext block. Of course, no such code books exist, but the idea is there. It treats each block separately. The encryption of each block is done individually and is unrelated to the encryption of later blocks. There are some benefits to this, though. This allows us to encrypt a whole bunch of blocks at once in parallel, it also allows us random access to encrypted data. That means once the data's encrypted, we can pick different parts of the ciphertext and decrypt them as we want. That's not something that we necessarily get from other modes. However, there are…
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