Anita and Bojan use Elgamal's signing scheme. Instead

generation of random numbers k use the following method:

First, they choose a random value k$0$;

For each i$-$th message that they sign, they choose ki $=$ k$0+$ i$.$

$1.$ Let's say that Bojan receives two consecutive messages signed by Anita,

i$.$e$.$ yields the following: $($xi; sig$($xi$))$ and $($xi$+1$; sig$($xi$+1))$:

Show how Bojan can quickly calculate Anita's private key, no

would know and calculate the discrete logarithm.