algorithm always generates the optimum solution
with polynomial time complexity. Another feature of
our implementation is an algorithm, which generates
the pay off for each participant. We compute VCG
pay–off which ensures the properties like efficiency.
It also ensures that truthful bidding is the dominant
strategy.
A bid in the forward auction (an ask in reverse
auction) describes the details of the items, its
quantity and price that the buyer is willing to pay.
Without loss of generality we assume that there are n
buyers (sellers). Additionally buyer (seller) can
describe capacity constraints. A buyer (seller) can
also use the marginal decreasing piecewise bidding
language used in (Kothari, 2003). This allows buyer
to specify the quantity range and price that buyer is
willing to pay as ([10,5),5) instead of single quantity
price pair. It is also an ordered list of attribute
names and values. Let there be a set of n bids, B
1
,
B
2
,…, B
n
. Each B
i
(Ai) is of the following type:
B
i
= ( (at
1
, v
1
), (at
2
, v
2
),…, (at
k
, v
k
)),
where at
j
denotes the j
th
attribute and
v
j
is the value
of the attribute.
The attributes describe different characteristics
of the items. Each attribute assumes the values from
the set of specified domains. For instance, the price
attribute will have values from set of positive real
numbers. The price and quantity are two attributes
of asks and bids. If buyer (seller) uses marginal
decreasing piecewise bidding language, then at
i
can
be a semi closed interval, which is open at one end.
Each buyer (seller) can specify m such intervals and
price pair. In this case we select only one point (on
an interval) for each buyer.
Our system is implemented as a web based
system which can be configured to be implemented
by third party auctioneers as well as enterprises. It
has got a parameterized policy module using which
levels of security, scheduling, type of auctions etc.
can be defined. Three different implementation
levels of security are provided in the system. In the
first level authentication by means of User-Id and
Password is provided. Once the user is successfully
authenticated, it uses Secure Socket Layer (SSL)
protocol for sending any message.
In the second level combination of User-Id,
Password and Public Key Cryptography is provided.
In this level it uses Public Key Infrastructure (PKI)
for implementing security. Each participant (i.e.
buyers, sellers, auctioneers) can optionally have a
key pair. The public key must be deposited with the
specified trusted third party (TTP). In this level use
of public key cryptography is optional. In the third
level the use of public key cryptography is
mandatory. In this case all the participants must
have key pair. In this implementation a bid or ask is
acceptable only if it is digitally signed by the sender
(i.e. buyer, seller or auctioneer). These levels help to
provide different levels of security in the system.
The level of security can be selected depending upon
the value of items. The auctioneer can enforce use
of public key cryptography in case of high value
items.
Another feature of our system is that its design
based on of Event-Condition-Action (ECA) rules.
Specific ECA rules can then be bound to different
events for versatile exception handling. Number of
different types of exceptions and events have been
defined in the system.
Events of different types can occur in this system
occur because of actions of different parties. The
action by buyer of submission of a bid will cause
occurrence of event like “Bid Arrived”. This event
will trigger activity like “Bid Validations”. This
activity will validate the bid. In case the bid is
invalid i.e. some of the attributes of bid violate some
constraints “Invalid Bid” exception will be raised,
sending appropriate notification to sender. In case
bid is valid an event “Bid Accepted” will occur.
There can be two types of events database events
and negotiation events. Events in the system like
“Bid Arrived” will be caused by actions of buyers.
When the event like “Acceptance Closure” occur, it
will automatically trigger of the algorithm to
generate optimum solution.
This system can be configured as sealed bid or
open depending upon the type of auction. In case of
sealed bid option bids (asks) will be submitted in
encrypted format and will be decrypted only after
the auction has closed. In this case it will not be
possible for the buyers (sellers) to see the bids (asks)
submitted by others. The system can also be
configured to accept more than one bid or ask from a
buyer or seller. However sender must specify which
bid or ask is final. If the information is not specified
then the last submitted bid (ask) is treated as final.
The complete cycle of stages in our system is as
follows:
(1) User Registration: The system requires that each
participant must register with system, before it
can be used. The user details are captured in
this phase.
(2) Auction Notification: Once the users are
registered with the system they can notify the
auction. The details of auctions like item
description, type, security level required etc. are
submitted by the users to the system. This
indicates the start of auction. An auction can be
initiated by a buyer or a seller. Optionally it is
also possible to submit the reservation price.
(3) Bid/Ask Submission: Once the auction is
notified the bids and asks can be submitted by
the registered users. At this time price and
quantity details are required to be submitted. In
AUCTION BASED SYSTEM FOR ELECTRONIC COMMERCE TRANSACTION
19