/// <summary>
/// Does the writing of transaction data to the user button as well
/// as actually signing the data with the coprocessor.
/// </summary>
private bool writeTransactionData(SHAiButtonUser user, int transID, int balance, byte[] accountData)
{
//init local vars
SHAiButtonCopr copr = this.copr;
int acctPageNum = user.AccountPageNumber;
byte[] scratchpad = this.writeTransactionData_scratchpad;
// length of the TMEX file - 28 data, 1 cont. ptr
accountData[I_FILE_LENGTH] = (byte)29;
// transaction ID - 2 data bytes
accountData[I_TRANSACTION_ID + 0] = (byte)transID;
accountData[I_TRANSACTION_ID + 1] = (byte)((int)((uint)transID >> 8));
// conversion factor - 2 data bytes
accountData[I_CONVERSION_FACTOR + 0] = 0x8B;
accountData[I_CONVERSION_FACTOR + 1] = 0x48;
// account balance - 3 data bytes
Convert.toByteArray(balance, accountData, I_BALANCE, 3);
// initial signature - 20 data bytes
copr.getInitialSignature(accountData, I_SIGNATURE);
// data type code - dynamic: 0x00, static: 0x01
accountData[I_DATA_TYPE_CODE] = 0x01;
// continuation pointer for TMEX file
accountData[I_CONTINUATION_PTR] = 0x00;
// clear out the crc16 - 2 data bytes
accountData[I_FILE_CRC16 + 0] = 0x00;
accountData[I_FILE_CRC16 + 1] = 0x00;
//we need to increment the writeCycleCounter since we will be writing to the part
int wcc = user.WriteCycleCounter;
if (wcc > 0)
{
//copy the write cycle counter into scratchpad
Convert.toByteArray(wcc + 1, scratchpad, 8, 4);
}
else
{
if (user.hasWriteCycleCounter())
{
// failed to read account data
this.lastError = SHATransaction.USER_READ_AUTH_FAILED;
return(false);
}
Array.Copy(ffBlock, 0, scratchpad, 8, 4);
}
// svcPageNumber, followed by address of device
scratchpad[12] = (byte)acctPageNum;
user.getAddress(scratchpad, 13, 7);
// copy in the signing challenge
copr.getSigningChallenge(scratchpad, 20);
// sign the data, return the mac right into accountData
copr.createDataSignature(accountData, scratchpad, accountData, I_SIGNATURE);
//after signature make sure to dump in the inverted CRC
int crc = ~CRC16.compute(accountData, 0, accountData[I_FILE_LENGTH] + 1, acctPageNum);
//set the the crc16 bytes
accountData[I_FILE_CRC16 + 0] = (byte)crc;
accountData[I_FILE_CRC16 + 1] = (byte)(crc >> 8);
//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//
OneWireEventSource.Log.Debug("------------------------------------");
OneWireEventSource.Log.Debug("writing transaction data");
OneWireEventSource.Log.Debug("acctPageNum: " + acctPageNum);
OneWireEventSource.Log.Debug("accountData: " + Convert.toHexString(accountData));
OneWireEventSource.Log.Debug("------------------------------------");
//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//
// write it to the button
try
{
if (user.writeAccountData(accountData, 0))
{
return(true);
}
}
catch (OneWireException owe)
{
OneWireEventSource.Log.Debug(owe.ToString());
}
this.lastError = SHATransaction.USER_WRITE_DATA_FAILED;
return(false);
}
/// <summary>
/// <P>Verifies user's account data. Account data is "verified" if and
/// only if the account balance is greater than zero and the digital
/// signature matches the signature recreated by the coprocessor.</P>
///
/// <P><B>Flow of action: </B>
/// <ul>
/// <li> Read the account data from user </li>
/// <li> Extract account balance </li>
/// <li> Debit money from balance </li>
/// <li> Insert the new balance </li>
/// <li> Reset the digital signature </li>
/// <li> Use coprocessor to sign account data </li>
/// <li> Insert the new digital signature </li>
/// <li> Write the account data to the user </li>
/// </ul></P>
///
/// <P>If previous steps have been executed, all "Read" commands on
/// the user are reading from cached data.</P>
/// </summary>
/// <param name="user"> SHAiButtonUser upon which the transaction occurs.
/// </param>
/// <returns> <code>true</code> if and only if the account balance is
/// greater than zero and digital signature matches the signature
/// recreated by the coprocessor.
/// </returns>
/// <seealso cref= SHAiButtonUser#readAccountData(byte[],int) </seealso>
/// <seealso cref= SHAiButtonCopr#verifySignature(byte[],byte[],byte[]) </seealso>
/// <seealso cref= #getLastError() </seealso>
public override bool verifyTransactionData(SHAiButtonUser user)
{
lock (this)
{
//clear any error
this.lastError = NO_ERROR;
//init local vars
byte[] scratchpad = this.verifyData_scratchpad;
byte[] accountData = this.verifyData_accountData;
byte[] verify_mac = this.verifyData_mac;
//if verifyUser was called, this is a read of cached data
int wcc = user.WriteCycleCounter;
//if verifyUser was called, this is a read of cached data
user.readAccountData(accountData, 0);
//get the user's balance from accountData
int balance = Convert.toInt(accountData, I_BALANCE, 3);
if (balance < 0)
{
this.lastError = USER_BAD_ACCOUNT_DATA;
return(false);
}
this.userBalance = balance;
//get the mac from the account data page
Array.Copy(accountData, I_SIGNATURE, verify_mac, 0, 20);
//now lets reset the mac
copr.getInitialSignature(accountData, I_SIGNATURE);
//and reset the CRC
accountData[I_FILE_CRC16 + 0] = 0;
accountData[I_FILE_CRC16 + 1] = 0;
//now we also need to get things like wcc, user_page_number, user ID
if (wcc < 0)
{
if (user.hasWriteCycleCounter())
{
// failed to read account data
this.lastError = USER_READ_AUTH_FAILED;
return(false);
}
//has no write cycle counter
Array.Copy(ffBlock, 0, scratchpad, 8, 4);
}
else
{
//copy the write cycle counter into scratchpad
Convert.toByteArray(wcc, scratchpad, 8, 4);
}
scratchpad[12] = (byte)user.AccountPageNumber;
user.getAddress(scratchpad, 13, 7);
copr.getSigningChallenge(scratchpad, 20);
if (!copr.verifySignature(accountData, scratchpad, verify_mac))
{
this.lastError = COPROCESSOR_FAILURE;
return(false);
}
return(true);
}
}
