On Mon, Nov 26, 2012 at 3:50 PM, Brian Carlstrom <[email protected]> wrote: > What problem are you seeing? When I run this on host with java, I get: > > Exception in thread "main" java.security.NoSuchAlgorithmException: Cannot > find any provider supporting AES/ECB/ZeroBytePadding > at javax.crypto.Cipher.getInstance(DashoA13*..) > at HelloWorld.main(HelloWorld.java:19) > > I think you want "AES/CCB/PKCS5Padding" as the CIpher algorithm. Running > with that with "java" on the host or "dalvikvm" on the device, I do get > garbage back. One issue I see is that you don't use the same IV for the two > ciphers, I'm guessing you are getting a random one for the second case. > > It does work for me in both cases if I switch from from using update to > doFinal with an argument: CCM is a shitty mode (IMHO). CCM does not fit well within Java's Init/Update/Final paradigm. Its an "offline" mode, meaning you must have the entire message before you can encrypt the data. That's because CCM encodes some parameters in the header block.
David Wagner has a nice Compare/Contrast of Authenticated Encryption modes at http://www.cs.berkeley.edu/~daw/talks/FSE04eax.ppt (paper: http://www.cs.berkeley.edu/~daw/papers/eax-fse04.ps) CWC, EAX, and GCM modes are much better choices if available. They are online and allow streaming of plaintext. The modes fit well into Java's Init/Update/Final paradigm. I think CCM got popular because of use in the WiFI gear from way back when. I was surprised NIST adopted it. That WiFi working group is the same group who gave us WPA. Verbum sat sapienti. Jeff > On Mon, Nov 19, 2012 at 9:45 AM, Antonino <[email protected]> > wrote: >> >> Hi all, >> I am trying a very simple function to encrypt and decrypt a string. >> With the following code the input string is different. >> Someone could help me? >> The code is not secure but it is not very important at the moment. >> >> String stringKey = "74dc6b9ec2bc29a5490744716e4a7a27"; >> String message = "FC:A1:3E:2A:79:B2"; >> >> SecretKeySpec sks; >> >> Cipher c,d; >> try { >> sks = new SecretKeySpec(stringKey.getBytes("UTF-8"),"AES"); >> c = Cipher.getInstance("AES/ECB/ZeroBytePadding"); >> c.init(Cipher.ENCRYPT_MODE, sks); >> c.update(message.getBytes("UTF-8")); >> byte[] ciphertext = c.doFinal(); >> Log.i("CE","crypted text: "+ Base64.encodeToString(ciphertext, >> Base64.DEFAULT)); >> //Decrypt block >> d = Cipher.getInstance("AES/ECB/ZeroBytePadding"); >> d.init(Cipher.DECRYPT_MODE, sks); >> d.update(ciphertext); >> byte[] deCiphertext =d.doFinal(); >> >> Log.i("CE","decrypted text: "+ new String(deCiphertext,"UTF-8")); >> } catch .... >> >> Thanks a lot >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Android Security Discussions" group. >> To view this discussion on the web visit >> https://groups.google.com/d/msg/android-security-discuss/-/F_kpTctUnSIJ. >> To post to this group, send email to >> [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/android-security-discuss?hl=en. > > > -- > You received this message because you are subscribed to the Google Groups > "Android Security Discussions" group. > To post to this group, send email to > [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/android-security-discuss?hl=en. -- You received this message because you are subscribed to the Google Groups "Android Security Discussions" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/android-security-discuss?hl=en.
