There exists a cipher that has perfect secrecy$.$

There exists a polynomial$-$time algorithm that takes any positive integers a and $b$ as input and

determines whether a and $b$ are coprime.

There exists a polynomial$-$time algorithm that takes any positive integer $n$ as input and returns a

prime factor of $n.$

There exists a polynomial$-$time algorithm that takes any positive integer $n$ as input and

determines whether $n$ is prime.

For every hash function, there exists an algorithm that finds a collision.

In a blockchain, every block $($except the last one$)$ contains a cryptographic hash of the previous

block.

In the bit commitment scheme based on quadratic residues, Bob can reveal the commitment

without Alice's key.

Problem $8(1$ point$)$

give the true or false