Thank you, I have now succesfully done some CMAC calculations.
I have one remaining problem: when the message is e.g. 6 byte,
according to the specification Padding bytes have to be added till the
correct block size is reached (eg 8 bytes). The first padding byte has
to be 0x80 the others 0x00. When I do this the output is not as
expected. In the next attempt I did not provide padding bytes and pass
the real length to the Updata function (eg. 6). This also did not give
the expected output.
The code I am using:
CMAC<AES> Cmac;
// Fill bKey; bTestdata with testdata : result in bTestDecr
Cmac.SetKey(bKey, sizeof(bKey));
Cmac.Update(bTestdata, sizeof(bTestdata));
Cmac.Final(bTestDecr);
Can anyone tell me what I do wrong ?
Regards,
Ger
On 20 okt, 02:25, "Wei Dai" <[email protected]> wrote:
> You're getting that error because CMAC doesn't need an IV. Call SetKey
> instead.
>
> --------------------------------------------------
> From: "Ger" <[email protected]>
> Sent: Thursday, October 15, 2009 2:07 AM
> To: "Crypto++ Users" <[email protected]>
> Subject: error on implementing CMAC in VS 2003
>
>
>
>
>
> > Hello,
>
> > I need to implement CMAC message authentication according to NIST
> > Special Publication 800-38B. I try to use the CMAC module from the
> > Crypto++ library (version 5.6), but until now I did not succeed.
> > I first wrote a short test program with some test data as input, so I
> > can verify the output.
> > I use Visual studio 2003 and the program is made in C++.
> > The program compile is okay, but when I run it, the program stops at
> > the “SetKeyWithIV” the message generated by Visual Studio is:
>
> > "Unhandled exception at <address> in <programName>: Microsoft C++
> > exception:
> > CryptoPP::AlgorithmParametersBase::ParameterNotUsed@<address>"
>
> > I have tried several version but this issue keeps coming up.
>
> > This is the code:
>
> > #include "cmac.h"
>
> > USING_NAMESPACE(CryptoPP)
>
> > USING_NAMESPACE(std)
>
> > BOOL TestCMAC()
> > {
> > byte iv[16];
> > byte bKey[16];
> > byte bTestdata[8];
> > byte bTestDecr[8];
> > CMAC<AES > Cmac;
>
> > // fill bKey with test data
> > // fill iv with test data
> > // fill bTestdata with test data
>
> > Cmac.SetKeyWithIV(bKey, sizeof(bKey), iv, sizeoff(iv)); // Here
> > the exception comes up
>
> > Cmac.Update(bTestdata, 8);
> > return (TRUE);
> > }
>
> > Does anyone have an idea what I am doing wrong?
>
> > Ger- Tekst uit oorspronkelijk bericht niet weergeven -
>
> - Tekst uit oorspronkelijk bericht weergeven -
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