NSData to Java String

Question

I've been writing a Web Application recently that interacts with iPhones. The iPhone iphone will actually send information to the server in the form of a plist. So it's not uncommon to see something like...

<key>RandomData</key>
<data>UW31vrxbUTl07PaDRDEln3EWTLojFFmsm7YuRAscirI=</data>

Now I know this data is hashed/encrypted in some fashion. When I open up the plist with an editor (Property List Editor), it shows me a more "human readable" format. For example, the data above would be converted into something like...

<346df5da 3c5b5259 74ecf683 4431249f 711630ba 232c54ac 9bf2ee44 0r1c8ab2>

Any idea what the method of converting it is? Mainly I'm looking to get this into a Java String.

Thanks!

Answer 1

After base64 decoding it you need to hex encode it. This is what PL Editor is showing you.

So...

<key>SomeData</key>
<data>UW31ejxbelle7PaeRAEen3EWMLojbFmsm7LuRAscirI=</data?

Can be represented with...

byte[] bytes = Base64.decode("UW31ejxbelle7PaeRAEen3EWMLojbFmsm7LuRAscirI=");
BigInteger bigInt = new BigInteger(bytes);
String hexString = bigInt.toString(16);
System.out.println(hexString);

To get...

<516df5aa 3c5b5259 74ecf683 4401259f 711630ba 236c59ac 9bb2ee44 0b1c8ab2>

Answer 2

According to our friends at wikipedia, the <data> tag contains Base64 encoded data. So, use your favorite Java "Base64" class to decode (see also this question).

ps. technically, this is neither "hashed" nor "encrypted", simply "encoded". "Hashed" implies a one-way transformation where multiple input values can yield the same output value. "Encrypted" implies the need for a (usually secret) "key" to reverse the encryption. Base64 encoding is simply a way of representing arbitrary binary data using only printable characters.