We consider the DiffieHellman key exchange scheme with certificates. We have a system with the three users Alice, Bob and Charley. The DiffieHellman algorithm uses p=61 and alpha=18. The three secret keys are a=11, b=22 and c=33. The three IDs are ID(A)=1, ID(B)=2 and ID(C)=3. For signature generation, the Elgamal signature scheme is used. We apply the system parameters p`=467, d`=127, alpha`=2 and . The CA uses the ephemeral keys k_E=213, 215 and 217 for Alices, Bobs and Charleys signatures, respectively. (In practice, the CA should use a better pseudorandom generator to obtain the k_E values.) To obtain the certificates, the CA computes x_i=4bi+ID(i) (where bi is the public key of person i) and uses this value as input for the signature algorithm. (Given x_i,ID(i) is then ID(i)=x_i mod 4.)

Problem 13.12 in the textbook: We consider the Diffie-Hellman key exchange scheme with certificates. We have a system with the three users Alice, Bob and Charley. The Diffie-Hellman algorithm uses p=61 and alpha=18. The three secret keys are a=11,b=22 and c=33. The three IDs are ID(A)=1,ID(B)=2 and ID(C)=3. For signature generation, the Elgamal signature scheme is used. We apply the system parameters p=467,d=127, alpha =2 and B. The CA uses the ephemeral keys k_E=213,215 and 217 for Alice's, Bob's and Charley's signatures, respectively. (In practice, the CA should use a better pseudorandom generator to obtain the k_E values.) To obtain the certificates, the CA computes xi=4bi+D (i) (where bi is the public key of person i) and uses this value as input for the signature algorithm. (Given xi,ID (i) is 1. Compute three certificates CertA, CertB and CertC: x1=x=x3=;s=;s=;s=mod466mod466mod466 2. Verify all three certificates: t_1=; t_2 2;t_3= 3. Compute the three session keys kAB=mod61,k_AC=mod 61 and k_BC =mod61