/** * Reads the account data off the SHAiButton using a READ_AUTHENTICATE command. First, this * function asserts that the account page number is known as well as the length of the account * file. Then it copies the 3 byte challenge to the scratchpad before sending the command for * READ_AUTHENTICATE. The 32 byte account data page is copied into dataBuffer starting at * dataStart. * * <p>In addition to the account data, this function also returns a calculated MAC. The MAC * requires 20 bytes after the start index. The return value is the write cycle counter value for * the account data page * * <p> * * @param chlg the buffer containing a 3-byte random challenge. * @param chlgStart the index into the buffer where the 3 byte challenge begins. * @param dataBuffer the buffer to copy the account data into * @param dataStart the index into the buffer where copying should begin * @param mac the buffer to copy the resulting Message Authentication Code * @param macStart the index into the mac buffer to start copying * @return the value of the write cycle counter for the page * @throws OneWireIOException on a 1-Wire communication error such as reading an incorrect CRC * from a 1-Wire device. This could be caused by a physical interruption in the 1-Wire Network * due to shorts or a newly arriving 1-Wire device issuing a 'presence pulse'. * @throws OneWireException on a communication or setup error with the 1-Wire adapter */ public synchronized int readAccountData( byte[] chlg, int chlgStart, byte[] dataBuffer, int dataStart, byte[] mac, int macStart) throws OneWireException, OneWireIOException { // init local variables OneWireContainer18 ibcL = this.ibc; byte[] rawData = this.readAccountData_rawData; byte[] scratchpad = this.readAccountData_scratchpad; // make sure account info is properly setup if (this.accountPageNumber < 0) { // user not setup return -1; } // copy challenge into scratchpad buffer System.arraycopy(chlg, 0, scratchpad, 20, 3); if (ibcL.eraseScratchPad(this.accountPageNumber)) { // send 1 byte RESUME, instead of 9 byte SELECT ibcL.useResume(true); // write the challenge to the device scratchpad if (ibcL.writeScratchPad(this.accountPageNumber, 0, scratchpad, 0, 32)) { // reads 42 bytes = 32 bytes of page data // + 4 bytes page counter // + 4 bytes secret counter // + 2 bytes CRC boolean readOK = ibcL.readAuthenticatedPage(this.accountPageNumber, rawData, 0); // read the scratchpad for mac int len = ibcL.readScratchPad(scratchpad, 0); // disable RESUME ibcL.useResume(false); if ((!readOK) || (len < 0)) { // read authenticate failed return -1; } // get the value of the write cycle counter int wcc = (rawData[35] & 0x0ff); wcc = (wcc << 8) | (rawData[34] & 0x0ff); wcc = (wcc << 8) | (rawData[33] & 0x0ff); wcc = (wcc << 8) | (rawData[32] & 0x0ff); // put the accountData in our local cache System.arraycopy(rawData, 0, this.accountData, 0, 32); // put the account data into return buffer System.arraycopy(rawData, 0, dataBuffer, dataStart, 32); // copy the mac into the return buffer System.arraycopy(scratchpad, 8, mac, macStart, 20); // \\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\ if (DEBUG) { IOHelper.writeLine("----------------------------------------------------------"); IOHelper.writeLine("User's ReadAuthPage"); IOHelper.write("address: "); IOHelper.writeBytesHex(this.address); IOHelper.writeLine("speed: " + this.ibc.getAdapter().getSpeed()); IOHelper.writeLine("RawData: "); IOHelper.writeBytesHex(rawData); IOHelper.writeLine("mac: "); IOHelper.writeBytesHex(mac, macStart, 20); IOHelper.writeLine("wcc: " + wcc); IOHelper.writeLine("----------------------------------------------------------"); } // \\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\ // cache the write cycle counter this.writeCycleCounter = wcc; return wcc; } // write scratchpad failed return -1; } // erase scratchpad failed return -1; }