Computer Security and Cryptography

17.2 THREATS TO NETWORK TRANSACTIONS

A transaction from the originator User_ID[A] to the recipient User_ID[B] involves the transmission of DATA, committing the users to some course of action. The participants require protection against a variety of harmful acts including:

Reneging: The originator subsequently disowns a transaction.

Forgery: The recipient fabricates a transaction.

Alteration: The recipient alters a previous valid transaction.

Masquerading: A user attempts to masquerade as another.

These actions are often indistinguishable; for example, User_ID[A] might attempt to renege on a transaction with User_ID[B] by claiming that

1. User_ID[B] has altered transaction data or
2. A third party, User_ID[C], has been masquerading as the originator.

Protocols have to be defined that at least detect attempts at alteration and to identify the source of Internet transactions.