Android Question [Solved]Problem with AES

[stefanoxjx]

Hi, because I need to share data with another application, I'm trying to decode data in AES.
From another application I encryped this string:

Hello from Stefano that trying to encrypt in AES

with password:

12345678901234567890123456789012

and the result is:

0x74, 0x02, 0x35, 0x19, 0x2E, 0x0E, 0x40, 0x41, 0x27, 0x2F, 0xC4, 0x00,
0xF7, 0xC1, 0x76, 0x9D, 0xE6, 0xC6, 0x76, 0xBA, 0x10, 0xC1, 0x4C, 0xF0,
0xC1, 0x81, 0x98, 0x40, 0x7B, 0x09, 0x3D, 0x1D, 0xE9, 0xD5, 0x53, 0x9F,
0xD4, 0x16, 0xF6, 0x20, 0xDA, 0xEB, 0xC7, 0x9D, 0xE4, 0x5F, 0x7E, 0x74

Now, I can to decrypt this with another application, but not with B4A.
With B4A I receive this error:

Error occurred on line: 453 (BT_Service)
javax.crypto.IllegalBlockSizeException: error:1e00007b:Cipher functions:OPENSSL_internal:WRONG_FINAL_BLOCK_LENGTH
    at com.android.org.conscrypt.NativeCrypto.EVP_CipherFinal_ex(Native Method)
    at com.android.org.conscrypt.OpenSSLCipher$EVP_CIPHER.doFinalInternal(OpenSSLCipher.java:570)
    at com.android.org.conscrypt.OpenSSLCipher.engineDoFinal(OpenSSLCipher.java:351)
    at javax.crypto.Cipher.doFinal(Cipher.java:1736)
    at anywheresoftware.b4a.object.B4XEncryption.Decrypt(B4XEncryption.java:47)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:197)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:193)
    at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
    at android.view.View.performClick(View.java:6291)
    at android.view.View$PerformClick.run(View.java:24931)
    at android.os.Handler.handleCallback(Handler.java:808)
    at android.os.Handler.dispatchMessage(Handler.java:101)
    at android.os.Looper.loop(Looper.java:166)
    at android.app.ActivityThread.main(ActivityThread.java:7523)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

The code used to decrypt is:

Dim e() As Byte = Array As Byte(0x74, 0x02, 0x35, 0x19, 0x2E, 0x0E, 0x40, 0x41, 0x27, 0x2F, 0xC4, 0x00, _
                                    0xF7, 0xC1, 0x76, 0x9D, 0xE6, 0xC6, 0x76, 0xBA, 0x10, 0xC1, 0x4C, 0xF0, _
                                    0xC1, 0x81, 0x98, 0x40, 0x7B, 0x09, 0x3D, 0x1D, 0xE9, 0xD5, 0x53, 0x9F, _
                                    0xD4, 0x16, 0xF6, 0x20, 0xDA, 0xEB, 0xC7, 0x9D, 0xE4, 0x5F, 0x7E, 0x74)


Dim Cipher As B4XCipher
Dim Decrypted() As Byte
   
Decrypted=Cipher.Decrypt(e, "12345678901234567890123456789012")

Where am I doing wrong?

Thanks.

 

[stefanoxjx]

I forgot...
The data is encrypted with AES ECB

 

[agraham]

You probably need to use my encryption library and not B4XCipher for third party AES encryption. B4XCipher is unique to B4X and data encrypted with it will have a salt and IV prepended which decrypt would expect. That's why you are getting a block length error as you have only the encrypted data.

My library is here

Base64 and Encryption library

Here's a library that, for the moment, can perform Base64 encoding and decoding and symmetric algorithm encryption and decryption. Tested symmetric algorithms are DES, Triple DES and AES (Rijndael). As the Java encryption rountines are all byte array oriented you will need my ByteConverter...

www.b4x.com

 

[stefanoxjx]

Hi agraham,
Your library seems to works fine.
Tomorrow I implement in my app.

Many thanks for your help.