1. What are some threats associated with a direct digital signature scheme?
a. The scheme validation is dependent on the security of the sender’s private key, which the sender can later claim lost or stolen and that the signature was forged when trying to deny sending a particular message.
b. If a private key is stolen from Bob at time t, the thief can send a message signed with Bob’s signature with a time stamp equal to or less than t.
c. The need for trust between 2 participants is a potential threat since there is no independent verification process.
2. How can you get physical possession of the password hashes from a MS Server 2008 running Active Directory?
a. To obtain hashes from a MS Server 2008, the system has to be compromised; domain hashes are stored in Active Directory on domain controllers while local account hashes are stored in the local SAM database. For member servers and workstations, a domain account’s password hashes can only be stored on systems where the user has performed an interactive logon. When an interactive logon occurs, the domain account's password hash will be stored on disk in the form of a cached-credentials hash.
b. I also need to have administrative rights on the compromised system, the tools required to retrieve domain password hashes, all require admin rights on a running systems. Some tools need to be able to elevate local SYSTEM privileges in order to access protected Registry files, while others work by injecting code into a running process via “SeDebugPrivilege”, which by default is granted only to administrators (Pilkington, 2012).
3. Explain the Diffie-Hellman key exchange like you were talking to a non-technical person.
a. Diffie-Hellman key exchange is one method of digital encryption, what is encryption you may ask: it is the process of encoding information in such a way that only authorized people can