EMVReadRecordCommand.java

public static byte[] readRecord(int recordNum, int sfi) {
        //Valid Record numbers: 1 to 255
        //Valid SFI: 1 to 30
        //SFI=0 : Currently selected EF
        if (recordNum < 1 || recordNum > 255) {
            throw new IllegalArgumentException("Argument 'recordNum' must be in the rage 1 to 255. recordNum=" + recordNum);
        }
        if (sfi < 0 || sfi > 30) {
            throw new IllegalArgumentException("Argument 'sfi' must be in the rage 1 to 30. Use 0 for currently selected EF. sfi=" + sfi);
        }

        byte P1 = (byte) recordNum;

        //00010100 = P2
        //00010    = SFI (= 2 << 3)
        //     100 = "Record number can be found in P1" (=4)
        byte P2 = (byte) ((sfi << 3) | 4);

        Log.debug("Iso7816Commands.readRecord() P1=" + P1 + " P2=" + P2);

        byte[] cmd = new byte[5];
        //00 = No secure messaging
        cmd[0] = 0x00;
        //B2 = READ RECORD
        cmd[1] = 0xb2;
        //P1 = Record number or record identifier of the first record to be read ('00' indicates the current record)
        cmd[2] = P1;
        //P2 = SFI + 4 (Indicates that the record number can be found in P1)
        cmd[3] = P2;
        cmd[4] = 0x00;
        return cmd;
    }