Let Ek$($x$)$ be the block encryption function of a block cipher. In particular, E is the block encryption algorithm, k is the symmetric key, and x is a block$-$length input.

The plaintext message is chopped into blocks m$0,$ m$1,$ m$2,...$ where mi is the ith plaintext block.

Also, we have a pseudo$-$random number generator G$($i$,$seed$)$ that takes a seed $($some initialisation value$)$ and for each index i generates a block$-$length pseudo$-$random output.

Suppose Alice uses the following algorithm to generate her ciphertext blocks:

ci $=$ Ek$($mi XOR G$($i$,$ seed$))$

What is the error propagation property of this cipher? $($a single bit of error in a single block of ciphertext leads to how many bits of error in the entire decrypted message?$)$

a$.$

a single bit on average

b$.$

half of the bits of a single block on average

c$.$

a single bit plus on average half of the bits of the next block

d$.$

all the blocks from the point of error onward will be corrupted.

e$.$

exactly a single bit