Does anybody know what encrypting technique is JDeveloper/SQL Developer using to persist credentials?

Note that Tim's password hash above is not for "apps_ro" - presumably he cut and pasted from the wrong place... I won't post the real password in case it's something he doesn't want shared!

I had a similar problem, trying to store my db credentials centrally (for non-secure databases!) and then exporting sql developer xml files. I have no idea what the algorithm is - however, you don't really need to know the algorithm, as you can just call the Oracle java API yourself. If you have SQLDeveloper, just grab the right Jar files:

cp /Applications/SQLDeveloper.App/Contents/Resources/sqldeveloper/BC4J/lib/db-ca.jar .
cp /Applications/SQLDeveloper.App/Contents/Resources/sqldeveloper/jlib/ojmisc.jar .

Then either load them in your Java app, or use something like JRuby as I do:

$jirb
> require 'java'
> require 'ojmisc.jar'
> require 'db-ca.jar'
> Java::oracle.jdevimpl.db.adapter.DatabaseProviderHelper.goingOut("password")    
 => "059D45F5EB78C99875F6F6E3C3F66F71352B0EB4668D7DEBF8" 
> Java::oracle.jdevimpl.db.adapter.DatabaseProviderHelper.goingOut("password")
 => "055CBB58B69B477714239157A1F95FDDD6E5B453BEB69E5D49" 
> Java::oracle.jdevimpl.db.adapter.DatabaseProviderHelper.comingIn("059D45F5EB78C99875F6F6E3C3F66F71352B0EB4668D7DEBF8")
 => "password" 
> Java::oracle.jdevimpl.db.adapter.DatabaseProviderHelper.comingIn("055CBB58B69B477714239157A1F95FDDD6E5B453BEB69E5D49")
 => "password" 

Note that the algorithm, whatever it is, has a random factor so the same password used twice can produce two different hex strings.

This solution works great for me... Copied from: http://www.mischiefblog.com/?p=912

import javax.crypto.*;
import javax.crypto.spec.*;
import java.security.*;

/**
 * Decrypt passwords stored in Oracle SQL Developer. This is intended for
 * password recovery.
 * 
 * Passwords are stored in
 * ~/.sqldeveloper/system2.1.1.64.39/o.jdeveloper.db.connection
 * .11.1.1.2.36.55.30/connections.xml
 */
public class Decrypt {
    public static byte[] decryptPassword(byte[] result)
            throws GeneralSecurityException {
        byte constant = result[0];
        if (constant != (byte) 5) {
            throw new IllegalArgumentException();
        }

        byte[] secretKey = new byte[8];
        System.arraycopy(result, 1, secretKey, 0, 8);

        byte[] encryptedPassword = new byte[result.length - 9];
        System.arraycopy(result, 9, encryptedPassword, 0,
                encryptedPassword.length);

        byte[] iv = new byte[8];
        for (int i = 0; i < iv.length; i++) {
            iv[i] = 0;
        }

        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(secretKey, "DES"),
                new IvParameterSpec(iv));
        return cipher.doFinal(encryptedPassword);
    }

    public static void main(String[] args) {
        if (args.length != 1) {
            System.err.println("Usage:  java Decrypt <password>");
            System.exit(1);
        }

        if (args[0].length() % 2 != 0) {
            System.err
                    .println("Password must consist of hex pairs.  Length is odd (not even).");
            System.exit(2);
        }

        byte[] secret = new byte[args[0].length() / 2];
        for (int i = 0; i < args[0].length(); i += 2) {
            String pair = args[0].substring(i, i + 2);
            secret[i / 2] = (byte) (Integer.parseInt(pair, 16));
        }

        try {
            System.out.println(new String(decryptPassword(secret)));
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
            System.exit(3);
        }
    }
}

I'm not sure about this but I always thought hashes can't be decrypted, only compared to another hash. MD5 generates a hash. The saved password in SQL Developer needs to be decrypted and send to the server. So the DES3Encrypt and DES3Decrypt procedures in dbms_obfuscation_toolkit package are a better bet. But the decrypt should be called before connecting to a database, so it's probably a Java crypto package with DES methods.

I don't know, but I wouldn't be surprised if it was DBMS_OBFUSCATION_TOOLKIT being used something like this:

l_hash := dbms_obfuscation_toolkit.md5(input_string=>:username||:password);

The length of the hash is 50 hex characters, which is 200 bits, so it may be the the hash of the password with a salt, prepended with the salt, like:

salt | hash(salt | password)

where | means concatenation.

Just speculation though. My guess would be a 40-bit salt and a SHA-1 hash, since SHA-1 produces 160-bit hashes.

Would be helpful to provide some input/output test data to check against!

FYI the password 'apps_ro' encrypts as:

     <StringRefAddr addrType="password">
        <Contents>051DC8A88C574538CC4AEE32D326E9480659C06CEC271EA6D7</Contents>
     </StringRefAddr>