What is the use of stream ciphers in information security?

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A stream cipher is an approaches of encryption where a pseudorandom cipher digit stream is mixed with plain text digits. This pseudorandom cipher digit stream is used to each binary digit, one bit at a time. This approach of encryption uses an infinite number of pseudorandom cipher digits per key.

A Stream Cipher can be used for symmetric key cryptography, or when the similar key is used to encrypt and decrypt data. A stream cipher encrypts an arbitrary length of plain text, one bit at a time, with an algorithm that needs a key.

For this type of encryption to remain secure, its psuedorandom cipher digits must be unpredictable and the key should not be used more than once. The pseudorandom cipher digits are produced through a number of random seed values that need digital shift registers.

The encryption of each digit is dependent on the recent state of the cipher, warranting the name state cipher for this. RC4 is a famous stream cipher that is generally used in software.

Stream ciphers appear in multiple flavors such as self-synchronizing stream ciphers compute each bit in the keystream as a function of the previous n bits in the keystream. It is defined as “self-synchronizing” because the decryption process can stay synchronized with the encryption process merely by understanding how far into the n-bit keystream it is.

One issue is error propagation; a garbled bit in transmission will result in n garbled bits at the receiving side. Synchronous stream ciphers makes the keystream in a fashion independent of the message stream but by utilizing the similar keystream generation function at sender and receiver. While stream ciphers do not propagate transmission bugs, they are by their nature, periodic so that the keystream will finally repeat.

The basic types of stream ciphers will also be defined as the modes of operation of stream ciphers, because it will be display that they can be transferred into each other by simple and general constructions. Likewise, several cryptographic primitives constructed from stream ciphers will also be defined as the modes of services of stream ciphers.

Some stream cipher in the KG mode can be transformed into the SCM mode by letting the next-state function based upon the current plaintext bit too. The main element to be respected in this regard is that a change of a single plaintext bit should provide rise to a random viewing change in the keystream (ciphertext) sequence to follow (forward propagation effect).

The KG mode should satisfy the same property, but regarding changes of the original state bits. Therefore, the adaptation is simply achieved by inserting the plaintext bit to one or more of the internal state bits, particularly those with the significant forward propagation effect.

Updated on 04-Mar-2022 11:08:10