Seed Labs $-$ Hash Length Extension AttackTask $2$: Create Padding

To conduct the hash length extension attack, we need to understand how padding is calculated for one$-$way

hash. The block size of SHA$-256$ is $64$ bytes, so a message M will be padded to the multiple of $64$ bytes

during the hash calculation. According to RFC $6234,$ paddings for SHA$256$ consist of one byte of $\backslash$x$80,$

followed by a many $0$s$,$ followed by a $64-$bit $(8$ bytes$)$ length field $($the length is the number of bits in the

M$)$