Cryptography: Question about streamcipher

46 Views Asked by At

My question is in Daniel J. Bernstein's ChaCha20, only nonce and counter changes each block. With nonce and counter, they are totally 128 bits,
however, it produces 512 bits keystream blocks. If we use the concept of a random number generater, the entropy is much smaller than output. Is it secure? Or how to explain its security.

0

There are 0 best solutions below