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This content has been automatically translated from Ukrainian.
CFB (short for Cipher Feedback) is one of the methods of data encryption that works on the principle of "chaining." Imagine you have a message that you want to encrypt, and you do it in blocks (for example, 16 bytes at a time). Each block is not encrypted separately but depends on the previous one, creating a domino effect.
How does Cipher Feedback work?
- Take an initial random piece of data (IV – Initialization Vector) and encrypt it.
- The resulting output is mixed (using the XOR operation) with the first block of plaintext. This is the first encrypted block.
- Then this encrypted block is used to encrypt the next block of text.
- And so on – each encrypted block affects the next one.
Simple examples
Secret chat. Imagine you are messaging in a secure messenger. To ensure that the message cannot be intercepted and altered without consequences, each piece of text is encrypted in a way that it depends on the previous one. If an attacker tries to change one word, it will spoil the entire subsequent text.
File encryption. Suppose you have a text document that needs to be stored in an encrypted form. Using CFB, the file will be encoded in such a way that changing one character in the plaintext will change the entire encrypted stream that follows it. This helps protect against data tampering.
Cipher Feedback in simple terms
- CFB allows encrypting a stream of data without a fixed block size (for example, in streaming video or audio).
- Changing one byte in the plaintext results in changes to all subsequent encrypted blocks, making forgery more difficult.
- Suitable for use in network protocols and messengers where encryption needs to work quickly and efficiently.
To simplify even further, CFB is like when you encrypt your message, and each subsequent part is encoded based on the previous one, creating a chain reaction effect.
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