public KRB_TGS_REP TGS(KRB_TGS_REQ req)
{
// Invent key K_AB
Key k_ab = new Key(7);
k_ab.CreateRandomKey();
// Decrypt TGT to get SA
Key sa = req.Tgt.GetKS_A(this.k_kdc);
// Decrypt authenticator
DateTime timestamp = req.Authenticator.GetTimestamp(sa);
// Verifies timestamp
DateTime now = DateTime.Now;
int diffTimestamp = now.Second - timestamp.Second;
if (diffTimestamp > this.maxTimestamp)
{
// Fail in the timestamp
return null;
}
// Finds Bob's master key KB
Key k_b = GetUserKey(req.ReqUser);
// Ticket to Bob = K_B[Alice, K_AB]
Ticket ticket = new Ticket(k_b, req.Tgt.GetUser(this.k_kdc), k_ab);
return new KRB_TGS_REP(sa, req.ReqUser, k_ab, ticket);
}
public KRB_TGS_REP(Key key, User reqUser, Key k_ab, Ticket ticket)
{
KRB_TGS_REP_NoEncrypted noEncrypt = new KRB_TGS_REP_NoEncrypted();
noEncrypt.reqUser = reqUser;
noEncrypt.k_ab = k_ab;
noEncrypt.ticket = ticket;
this.encrypted = DesEncryption.EncryptObject(noEncrypt, key);
}
public KRB_AP_REQ(Ticket ticket, Authenticator authenticator)
{
this.ticket = ticket;
this.authenticator = authenticator;
}