AES in Gingerbread

by Steve Hugg » Fri, 10 Dec 2010 11:59:24 GMT


Sponsored Links
 In Gingerbread, I'm decoding some previously-encoded data with the
following:

    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    byte[] decrypted = cipher.doFinal(encrypted);

I now get this exception:

javax.crypto.BadPaddingException: pad block corrupted
 at
org.bouncycastle.jce.provider.JCEBlockCipher.engineDoFinal(JCEBlockCipher.java:
715)
 at javax.crypto.Cipher.doFinal(Cipher.java:1090)

I see that BouncyCastle was upgraded from 1.34 to 1.45; does anyone
know what might be causing this code to behave differently?

-- 



Re: AES in Gingerbread

by Steve Hugg » Sat, 11 Dec 2010 03:30:07 GMT


 More debugging on this issue...

I am using this method to generate keys from a passphrase:

                KeyGenerator kgen = KeyGenerator.getInstance("AES", "BC");
                SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", 
"Crypto");
                sr.setSeed(seed);
                kgen.init(128, sr);
                SecretKey skey = kgen.generateKey();
                byte[] raw = skey.getEncoded();

This results in a different key for a given passphrase on 2.3 than it
does on 1.5-2.2.

Froyo returns this information for KeyGenerator and SecureRandom
objects:

AES BC version 1.34
SHA1PRNG Crypto version 1.0

Gingerbread returns:

AES BC version 1.45
SHA1PRNG Crypto version 1.0

-- 


Sponsored Links


Re: AES in Gingerbread

by Tim » Mon, 27 Dec 2010 09:22:25 GMT


 I have exactly the same problem. How did you handle this Steve?




-- 



Re: AES in Gingerbread

by nick » Mon, 27 Dec 2010 09:56:47 GMT


 

How exactly are you generating your key from a password? If 'seed' is your 
password, 
this code is very wrong. You should use password-based encryption to 
generate 
a key from password. Something like:

 PBEParameterSpec  pbeParamSpec = new PBEParameterSpec(salt, count);
 PBEKeySpec  pbeKeySpec = new PBEKeySpec(password);
 SecretKeyFactory  keyFactory = 
SecretKeyFactory.getInstance("PBEWithSHA1AndAES");
 SecretKey pbeKey = keyFactory.generateSecret(pbeKeySpec);
 

-- 



Re: AES in Gingerbread

by Bob Kerns » Mon, 27 Dec 2010 19:33:22 GMT


 I wonder if you realize that sr.setSeed(seed) does *NOT*, repeat *NOT*
set a SecureRandom to produce a predictable series of values?

Not only would that no longer be secure, it's not what setSeed() does
for a SecureRandom. Instead, it supplements the existing seed (which
is beyond your control when created as below). You'd have to supply
the seed in the constructor.

And if you are expecting SecureRandom to produce the same series of
values (as seen by KeyGenerator), or KeyGenerator to produce the same
key, between two versions of the OS, you're relying on something which
is not documented. Reproducability is just not part of their job.

I strongly suspect (and fear) that you're screwed, and your users are
likely screwed as well. Sorry to deliver bad news. If you like, post
more about what you're doing and maybe we can help you figure out the
way forward.




-- 



Other Threads

1. How to custom option menu to arrange three menu items where 2 menu items are displayed at the top and the third below it.

Dear All,

        Please note that the custom option like I said is actually possible, 
your can visit the following link:
http://androidandme.com/wp-content/uploads/2009/12/05.categories_optionmenu.jpg

        I just want to custom option menu like that, any suggestion will be 
grateful.

        Thanks,

Best Regards,
D.Y

----------
 android-developers@googlegroups.com 
[mailto:android-develop...@googlegroups.com]  String
€ 2010820:34
 Android Developers
: [android-developers] Re: How to custom option menu to arrange three menu 
items where 2 menu items are displayed at the top and the third below it.





Can't do it. The OS arranges menu items as it pleases. For 3 items,
the arrangement is all on one line.

If you want different, you'll need to build your own menu-simulation
class - which isn't actually that hard, using the standard Android
layout widgets.

String

-- 

2. <WTA> About sms...!

mau tny saya ada masalah pd sms di dream tdk bs mengirim sms sm sekali tp
untuk terima telf dan nerima sms bs dan pls jg ada...pdahal byasanya ga kya
gini apa ada yg pernah pny masalah yg sama...
mhon percerahannya suhu..

-- 
"Indonesian Android Community [id-android]" 

3. xl brmslah?

4. progress bar in a tabhost

5. Getting entity/body from an http post request

6. WebView not loading properly in 2.1

7. bluetooth - IOException: Connection refused