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Stream cipher

Stream cipher

Stream cipher definition

A stream cipher is an encryption technique that operates on a continuous stream of data. It converts text into code byte-by-byte and makes it unreadable and unreachable to those who don’t have the right key. A stream cipher is a form of symmetric encryption, meaning it can also decrypt messages with the same key it used to encrypt them. The security of a stream cipher relies on the generation of an unpredictable and statistically random keystream.

See also: ciphertext, end-to-end encryption

Stream cipher benefits

  • Stream ciphers are faster than other types of encryption, such as block ciphers.
  • Can be easily incorporated into modern programs.
  • Doesn’t require complex hardware to function.
  • Stream ciphers are easy to use and don’t require public and private keys.
  • Ideal for devices that have fewer resources.

Popular stream ciphers

RC4-RC4. RC4-RC4 stands for Rivest Cipher 4. It is the most popular stream cipher because it was widely used in the past for various applications, including early versions of WPA (Wi-Fi Protected Access), WEP (Wired Equivalent Privacy), and TLS. RC4-RC4 is simple and fast, but it also comes with many risks, making it more risky than others. Thus, it is no longer recommended for use in new systems or protocols.

A5/1. A5/1 is a synchronization algorithm that has a 64-bit secret key and is mostly used to provide security and privacy in the GSM (Global System for Mobile Communications) standard. It is responsible for generating keystreams that are used for the encryption and decryption of GSM voice calls. However, it was discovered that A5/1 also has many security weaknesses because there have been many successful attacks against it. So, it is considered weak for modern security standards.

A5/2. A5/2 is another synchronization algorithm used in the GSM protocol. It provided voice privacy within the protocol and was most commonly used in Asia and other export regions. It was developed as a weaker alternative to A5/1 to meet export regulations at the time. However, it also has significant security weaknesses and is considered inadequate for modern security requirements.

Further reading

Ultimate digital security