WEP’s vulnerabilities weren’t because it used RC4, but instead because it did not follow a basic rule of a stream cipher: Don’t reuse keys. It’s worthwhile pointing out that this is the same RC4 used in WEP. The most commonly used version is RC4 (also called ARC4), which is a symmetric stream cipher and it can use between 40 and 2,048 bits.
#STREAM CIPHER CODE#
Ron Rivest invented several versions of RC, which are sometimes referred to as Ron’s Code or Rivest Cipher. Stream ciphers are more efficient than block ciphers when encrypting data in a continuous stream. Block ciphers encrypt data in a specific-sized block such as 64-bit or 128-bit blocks. Stream ciphers encrypt data a single bit, or a single byte, at a time in a stream.
#STREAM CIPHER CRACK#
Attackers discovered they could use packet injection techniques to increase the number of packets on a wireless network, detect the duplicate keys, and crack the encryption. If wireless systems generate enough traffic, WEP reuses keys for RC4. RC4 is a secure algorithm when it’s implemented correctly, but WEP did not follow the important stream cipher principle of never reusing keys.
WEP uses Rivest Cipher 4 (RC4) stream cipher for symmetric encryption. Note that WEP is not recommended for use, and part of the reason is due to how it implemented the stream cipher. If a key is reused, it is easier to crack the encryption.įor example, Chapter 4 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide discussed the legacy Wired Equivalent Privacy (WEP) and initialization vector (IV) attacks. Block ciphers are more efficient when the size of the data is known, such as when encrypting a file or a specific-sized database field.Īn important principle when using a stream cipher is that encryption keys should never be reused. In general, stream ciphers are more efficient than block ciphers when the size of the data is unknown or sent in a continuous stream, such as when streaming audio and video over a network. Stream ciphers encrypt data as a stream of bits or bytes rather than dividing it into blocks. The block cipher divides large files or messages into these blocks and then encrypts each individual block separately. However, they divide data in different ways.Ī block cipher encrypts data in specific-sized blocks, such as 64-bit blocks or 128-bit blocks. They are both symmetric, so they both use the same key to encrypt or decrypt data. Most symmetric algorithms use either a block cipher or a stream cipher. More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available here. Which of the following would be the FASTEST, while also providing strong confidentiality? An application developer needs to use an encryption protocol to encrypt credit card data within a database used by the application.
Do you know the differences between a block cipher and a stream cipher? You should if you plan to take the Security+ exam. This post should help you to have a basic understanding of appropriate encryption methods such as symmetric encryption.įor example, can you answer this question?
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