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In cryptography, the shrinking generator is a form of pseudorandom number generator intended to be used in a stream cipher. It was published in Crypto 1993 by Don Coppersmith, Hugo Krawczyk and Yishay Mansour. [1] The shrinking generator uses two linear-feedback shift registers.
Multiple ciphers including TEA and Red Pike use 2654435769 or 0x9e3779b9 which is ⌊ 2 32 /ϕ ⌋, where ϕ is the golden ratio. The BLAKE hash function , a finalist in the SHA-3 competition , uses a table of 16 constant words which are the leading 512 or 1024 bits of the fractional part of π .
In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code, or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet .
According to the authors, the structure of the cipher is influenced by the stream cipher SNOW and the block cipher Serpent. The cipher has an improved performance compared with Snow, more specifically by having a faster initialization phase. The cipher key length can vary between 128 and 256 bits, but the guaranteed security is only 128 bits ...
Although there are 26 key rows shown, a code will use only as many keys (different alphabets) as there are unique letters in the key string, here just 5 keys: {L, E, M, O, N}. For successive letters of the message, successive letters of the key string will be taken and each message letter enciphered by using its corresponding key row.
The standard English straddling checkerboard has 28 characters and in this cipher these became "full stop" and "numbers shift". Numbers were sent by a numbers shift, followed by the actual plaintext digits in repeated pairs, followed by another shift. Then, similarly to the basic Nihilist, a digital additive was added in, which was called ...
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. If a ciphertext number becomes larger than 25 we wrap it to a value between 0-25.
The number of full cycles depends on the block size, but there are at least six (rising to 32 for small block sizes). The original Block TEA applies the XTEA round function to each word in the block and combines it additively with its leftmost neighbour. Slow diffusion rate of the decryption process was immediately exploited to break the cipher.