Master of Science thesis Fighting Spam

}
public synchronized StatusPacket activationRequest(String username,
RegistrationInfoPacket pack) throws
Exception
{
Debugger.debug(getClass(), 1, "Activationrequest... User: " + username);
used");
BankAccount acc = accounts.getAccount(username);
Debugger.debug(getClass(), 1, "Found account.");
Debugger.debug(getClass(), 1, "Testing if activationNumber has already been
if(acc.activationNumbers.contains(new Long(pack.activationNumber)))
return new StatusPacket(true, "activationNumber accepted.");
acc.activationNumbers.addElement(new Long(pack.activationNumber));
Debugger.debug(getClass(), 1, "activationNumber has NOT been used before.");
session RSsession = createRSSession();
RSsession.send(new ActivationPacket(pack.activationNumber,
Cryptotools.sign(super.privateKey, new
Long(pack.activationNumber))));
// CurrencyServer now tries to retrieve the users certificate from the
registration server
while(true)
{
RSsession.send(new RegistrationInfoPacket(pack.activationNumber));
NetPacket packet = RSsession.receive();
if(packet instanceof ActivationCompletedPacket)
{
acc.cert = ((ActivationCompletedPacket) packet).certificate;
Debugger.debug(getClass(), 1, "Certificate succesfully retrieved from
RS.");
break;
}
else if(packet instanceof StatusPacket)
{
Debugger.debug(getClass(), 1, "Error retrieving certificate from RS.");
return new StatusPacket(false, "Error generating certificate.");
}
else
throw new Exception("Error in getting certificate from RS. Server
responded unexpectedly.");
}
Debugger.debug(getClass(), 1,
"Withdrawing the registrationFee " + Config.registrationFee + " +
" + Config.registrationCoinValue
+ ".");
acc.withdrawNoteUpFront(Config.registrationFee + Config.registrationCoinValue);
Debugger.debug(getClass(), 1, "ActivationRequest completed for user: " +
username);
}
return new StatusPacket(true, Config.registrationCoinValue);
private session createRSSession() throws Exception
{
Debugger.debug(getClass(), 3, "Creating new session with the RS: " +
Config.RSAddress + ":" + Config.RSPort);
Socket socket = new Socket(InetAddress.getByName(Config.RSAddress),
Config.RSPort);
return new session(socket, false, RSPublicKey, true);
}
public synchronized CoinSignaturePacket blindingFactor(String username,
CurrencyBlindingFactorPacket cp) throws
350