In cryptography, a **keystream** is a stream of random or pseudorandom characters that are combined with a plaintext message to produce an encrypted message (the ciphertext).

The "characters" in the keystream can be bits, bytes, numbers or actual characters like A-Z depending on the usage case.

Usually each character in the keystream is either added, subtracted or XORed with a character in the plaintext to produce the ciphertext, using modular arithmetic.

Keystreams are used in the one-time pad cipher and in most stream ciphers. Block ciphers can also be used to produce keystreams. For instance, CTR mode is a block mode that makes a block cipher produce a keystream and thus turns the block cipher into a stream cipher.

### Other articles related to "keystream":

**Keystream**- Example

... The random numbers in the

**keystream**then have to be at least between 0 and 25 ... To encrypt we add the

**keystream**numbers to the plaintext ... And to decrypt we subtract the same

**keystream**numbers from the ciphertext to get the plaintext ...

Stream Cipher - Loose Inspiration From The One-time Pad

... A one-time pad uses a

... A one-time pad uses a

**keystream**of completely random digits ... The**keystream**is combined with the plaintext digits one at a time to form the ciphertext ... However, the**keystream**must be (at least) the same length as the plaintext and be generated completely at random ...Autokey Cipher

... A key-autokey cipher uses previous members of the

... A key-autokey cipher uses previous members of the

**keystream**to determine the next element in the**keystream**... previous message text to determine the next element in the**keystream**...Correlation Attack - Explanation

... between the output state of one individual LFSR in the

... between the output state of one individual LFSR in the

**keystream**generator and the output of the Boolean function that combines the output state of all of the LFSRs ... Combined with partial knowledge of the**keystream**(which is easily derived from partial knowledge of the plaintext, as the two are simply XORed together), this allows an attacker to brute-force ... For instance, if, in a**keystream**generator in which four 8-bit LFSRs are combined to produce the**keystream**, and one of the registers is correlated to the ...Solitaire (cipher) - Encryption and Decryption

... Each value of the

... Each value of the

**keystream**is to be used for one value of the message, thus the**keystream**will need to be the same length as the message ... To encrypt a message, add each**keystream**value to its corresponding character in the plaintext, rolling over back to 1 if the resulting value exceeds 26 (modulo 26 arithmetic) ... To decrypt, subtract each**keystream**value from its corresponding character in the ciphertext, rolling back up to 26 if the resulting value should be lower than 1 ...Main Site Subjects

Related Subjects

Related Phrases

Related Words