Phase description

This section describes the process of an auction phase by phase.

1. Advertising Phase: The auction specification is input to the auction controller. The auction specification includes the opening time, closing time, auction evaluation algorithm, result disclosure rules, and other parameters if necessary. The auction specification is depicted in Figure 2. The auction controller generates a nonce auction ID and signs the concatenation of the auction ID and the auction specification. An advertisement of the auction is then published. The advertisement should contain sufficient information for participants to identify and evaluate the trustworthiness and behavior of the marketplace with the given parameters. Figure 3 shows the advertising phase.
2. Opening Phase: At the opening time of an auction, the auction controller enables the bids collector to collect incoming bids.
3. Collection Phase: During the bids collection phase, the bids collector receives bids. It validates the bids, including the verification of the auction ID. If the check is successful, the bids collector signs the hash of the bid message with the auction ID and returns the signature. Furthermore, it inserts the bid into the bids table. A bid includes the auction ID, a bid strategy and other payload according to the specific auction, such as bidder ID and digital cash. The messages included in this phase are illustrated as the following:

   $Bidder\to Marketplace:\; \{auction\; ID,\; bid,[Optional\; Fields]\}$K_SMP

   $Marketplace\to Bidder:$
   $\{auction\; ID,Timestamp,\; H(bid\; message)\}$K_SMP^-1

   Figure 4 depicts the opening and collection phase.

4. Closing Phase: At the closing time of an auction, the auction controller disables the bids collector to collect any more bids.
5. Evaluation Phase: The auction controller invokes the auction evaluation algorithm with the bids table as argument which generates the result. Figure 5 depicts the evaluation phase.
6. Result-Disclosure Phase: The auction controller signs the concatenation of the final result and the auction ID and sends it out.

  
Figure 2: Auction specification and auction advertisement. For this and the following three figures: The round boxes represent entities, and the square boxes represent information.

  
Figure 3: Auction advertisement phase

  
Figure 4: Auction opening and collecting phase

  
Figure 5: Auction evaluation phase