Secret Password Encryption - Expert Oracle and Java Security - page 89

}
We've discussed a lot of the Exception handling already. This method is generally called first of the
current foursome, and includes a bit more error reporting. Because we are returning a RAW , we can return
up to 32,767 bytes of data. In the catch block, we instantiate a CharArrayWriter of size 32,767 characters
in an array in memory. Then by stacked calls, we instantiate a PrintWriter , which points at the
CharArrayWriter . Then we print the Exception s tack trace to that PrintWriter . As a result, we get the
stack trace in a char array writer, errorText . We call errorText.toString().getBytes() to get a byte array
of the stack trace, and then we instantiate a RAW from that, which we can pass back to the client.
At the client, if we have trouble deciphering the passphrase that we are seeking from the RAW that has
been returned, we can read the RAW as a String and see the Exception stack trace. This is a handy
troubleshooting practice in a client/server environment when you'd like to see the error that the server
sees, not just the error at the client.
Listing 6-6 shows the second of this bunch of methods. This one returns the name of the actual
algorithm that's in use on the Oracle database. In the try block, you'll see a feature common to all these
methods. We test to see if the sessionSecretDESKey is null , and if it is, we call
makeSessionSecretDESKey() (described earlier) to create the secret password key.
Listing 6-6. Encrypt the Algorithm Name, getCryptSessionSecretDESAlgorithm ()
public static final RAW getCryptSessionSecretDESAlgorithm(
String extRSAPubMod, String extRSAPubExp )
{
RAW rtrnRAW =
new RAW( "getCryptSessionSecretDESAlgorithm() failed" .getBytes() );
try {
if( null == sessionSecretDESKey ) makeSessionSecretDESKey() ;
rtrnRAW = getRSACryptData ( extRSAPubMod, extRSAPubExp,
sessionSecretDESAlgorithm );
} catch( Exception x ) {}
return rtrnRAW;
}
The last common call in the try block is a call to the getRSACryptData() method described
previously) to encrypt the secret password key artifact; in this case, the algorithm name. That generates a
RAW data type containing the encrypted artifact, which will be returned to the client.
Please take note of what is returned if an exception is called. We still return rtrnRAW , but its value is
the bytes of the string "getCryptSessionSecretDESAlgorithm() failed" . Having this reported back to the
client can be helpful for troubleshooting. Also, note how we get the bytes of that String —we treat the
value between quotation marks as if it were already a String object, calling the getBytes() method. Is
that allowed? Yes!
The last two methods in this group, shown in Listings 6-7 and 6-8, return the salt and iteration count
as encrypted RAW data types.
Listing 6-7. Encrypt the Salt, getCryptSessionSecretDESSalt ()
public static final RAW getCryptSessionSecretDESSalt( String extRSAPubMod,
String extRSAPubExp )
{
RAW rtrnRAW = new RAW( "getCryptSessionSecretDESSalt() failed".getBytes() );
try {
if( null == sessionSecretDESKey ) makeSessionSecretDESKey();