AES, ECB mode decrypt error

[Dwight Kulkarni]

Hello,

I had Crypto PP code that was previously working and recently stopped working. We moved to a new version of our BSP.

Error is:

terminate called after throwing an instance of 'CryptoPP::AlgorithmParametersBase::ParameterNotUsed'
  what():  AlgorithmParametersBase: parameter "IV" not used

Error is traced to this particular function below. 

I had it running with the Params in ECB mode still passing in the IV.

d.SetKey(key, key.size(),params);

Then I commented it out with:

d.SetKey(key, key.size());

Previously, it wasn't throwing an error even if IV is passed in ECB mode. 

Also, I don't know why it's falling through the catch statement and kills my program.

should I have a generic catch statement Exception e  to prevent this ?

std::string decrypt_aes(std::string cipherbytes, SecByteBlock key, SecByteBlock iv) {

try {

AlgorithmParameters params = MakeParameters(Name::FeedbackSize(), 1/*8-bits*/)

(Name::IV(), ConstByteArrayParameter(iv));

//CFB_Mode<AES>::Decryption d;

ECB_Mode<AES>::Decryption d;

std::string recovered;

//d.SetKey(key, key.size(),params);

d.SetKey(key, key.size());

StringSource s(cipherbytes, true, new StreamTransformationFilter(d, new StringSink(recovered), CryptoPP::BlockPaddingSchemeDef::PKCS_PADDING));

return recovered;

}

catch (CryptoPP::Exception e) {

std::cerr << e.what() << std::endl;

return "";

}

} 

[Dwight Kulkarni]

Hi,

It started working after I commented out the AlgorithmParameters params line.

I thought the d.SetKey(..) change would fix it, but it didn't seem to.

[Jeffrey Walton]

BlockPaddingSchemeDef::PKCS_PADDING is incorrect for ECB mode. ECB
mode does not use padding. The programmer is responsible for padding
to block size.

Jeff