[erlang-questions] Problem with legacy code when upgrading to R16B03

[Ryan Brown]

Thank you Felix. I did get that to work standalone. It appears that there
is something in the pad_binary method that I have not been able to
track-down.

In a crude attempt to trace the issue down, I added a bunch of io:formats
and ran in the shell.

pad_binary_128(Data) when bit_size(Data) > 128 ->
  io:format("Line ~p~n", [89]),
  {Kept, _Lost} = split_binary(Data, size(Data) - 1),
  io:format("Line ~p~n", [94]),
  pad_binary_128(Kept);
pad_binary_128(Data) when bit_size(Data) < 128 ->
  io:format("Line ~p~n", [97]),
  pad_binary_128(<<Data/binary,0:1>>);
pad_binary_128(Data) ->
  io:format("Line ~p~n", [100]),
  Data.

This is the output I get:

Line 97
** exception error: bad argument
     in function  omac1:pad_binary_128/1 (src/omac1.erl, line 97)
     in call from omac1:cmac_aes_cbc_128/6 (src/omac1.erl, line 78)

So, it almost seems like there may be a difference in the way that
bit_size/1 is handled in R1603. However, I do not see anything that
stands-out to me in the docs.

http://erldocs.com/R15B01/erts/erlang.html?i=0&search=erlang:bit#bit_size/1
http://erldocs.com/R16B03/erts/erlang.html?i=0&search=erlang:bit#bit_size/1

Thanks in advance.

Best,

Ryan

On Tue, Feb 17, 2015 at 5:21 PM, Felix Gallo <felixgallo@REDACTED> wrote:

> I made your same changes to the module, and also added the following
> function to the module:
>
> test() ->
>   Key = <<1:128>>,
>   Data = <<1:128>>,
>   generate_tag_aes_cbc_128(Key, Data).
>
> and when run in a shell:
>
> Eshell V6.1  (abort with ^G)
> 1> c(omac1),l(omac1),omac1:test().
> <<173,219,62,66,7,255,149,96,196,74,41,116,238,229,211,35>>
>
> this appears to work (at least, it doesn't crash with badarg.  I don't
> know whether the data is correct).  Are you sure your aes key is 128, 192,
> or 256 bits long?  It's possible the crypto module is throwing badarg when
> it detects an improper length key.
>
> On Tue, Feb 17, 2015 at 3:27 PM, Ryan Brown <ryankbrown@REDACTED> wrote:
>
>> Thank you Felix. It looks like the aes_cbc_128_encrypt method is gone so
>> I changed all to use crypto:block_encrypt(aes_cbc128, Key, IV,
>> ToBeEncrypted)
>>
>> But alas, I'm still seeing the same error.
>>
>> On Tue, Feb 17, 2015 at 3:10 PM, Felix Gallo <felixgallo@REDACTED>
>> wrote:
>>
>>> I'm not super familiar with the crypto library, but it looks like its
>>> function signatures changed significantly between 15B01 and 16B03.  In
>>> particular, it appears that some of the functions you are calling are no
>>> longer in the library, and have been replaced with equivalents.
>>>
>>> I suggest opening
>>>
>>> http://erldocs.com/R15B01/crypto/crypto.html
>>>
>>> and
>>>
>>> http://erldocs.com/R16B03/crypto/crypto.html
>>>
>>> and seeing if you can figure out where the changes occurred.  I suspect
>>> those are the cause of your badargs.
>>>
>>> F.
>>>
>>> On Tue, Feb 17, 2015 at 1:55 PM, Ryan Brown <ryankbrown@REDACTED>
>>> wrote:
>>>
>>>> Hello all,
>>>>
>>>> I am in the process of upgrading a legacy application from R15B01 to
>>>> R16B03 in order to get SHA 384 support. However, I am getting an error
>>>> creating my CMAC from the library located here:
>>>>
>>>> https://github.com/PearsonEducation/subpub/blob/master/src/omac1.erl
>>>>
>>>> For the life of me I cannot find the root cause. I am just receiving a
>>>> badarg error pointing to line 74.
>>>>
>>>> Any guidance would be greatly appreciated.
>>>>
>>>> Thank you.
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> erlang-questions mailing list
>>>> erlang-questions@REDACTED
>>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>>
>>>>
>>>
>>
>
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