Decrypting text encrypted using CBC Blowish in perl using Crypto++

[Troy]

Hello,

I have been trying to figure out how to get decrypting of text in perl working in crypto++ (and possibly the reverse).

#!/usr/bin/perl

use Crypt::CBC;

$iv = "12345678";

$cipher = Crypt::CBC->new( -literal_iv => 1, -literal_key => 1, -key => "wowsers ", -iv => $iv, -header => "none");

$plaintext = "my message";

$ciphertext = $cipher->encrypt_hex($plaintext);

$hex_iv = unpack('H*', $iv);

print "$hex_iv$ciphertext\n";

$plaintext = $cipher->decrypt_hex($ciphertext);

print "$plaintext\n";

As per the options enabled in perl, I have disabled all of the default features and am trying to get it working with a literal key and literal iv (which is being prepended to the output.

I am then failing to decrypt the message using the following crypto++ code:

    void prepare_key(std::string& key)

    {

      ssize_t len = static_cast<ssize_t>(key.length());

      if (len < Blowfish::MIN_KEYLENGTH)

        key.append(Blowfish::MIN_KEYLENGTH - len, ' ');

      else

      if (len > Blowfish::MAX_KEYLENGTH)

        key.erase(Blowfish::MIN_KEYLENGTH);

      else

      {

        size_t remainder = len % Blowfish::BLOCKSIZE;

        if (remainder) key.append(Blowfish::BLOCKSIZE - remainder, ' ');

      }

    }

  

    bool encrypt(const std::string& source,

                 std::string& dest,

                 std::string key)

    {

      prepare_key(key);

      

      AutoSeededRandomPool prng;

      byte iv[Blowfish::BLOCKSIZE];

      prng.GenerateBlock(iv, sizeof(iv));

      dest.clear();

      try

      {

        CBC_Mode<Blowfish>::Encryption e;

        e.SetKeyWithIV(reinterpret_cast<const byte*>(key.c_str()), key.length(), iv);

        

        StringSource(source, true,

            new StreamTransformationFilter(e,

                new StringSink(dest)

            )

        );

      }

      catch (const Exception& e)

      {

        return false;

      }

      dest.insert(dest.begin(), std::begin(iv), std::end(iv));

      

      return true;

    }

  

    bool decrypt(std::string source, std::string& dest, std::string key)

    {

      prepare_key(key);

      

      AutoSeededRandomPool prng;

      byte iv[Blowfish::BLOCKSIZE];

      std::memcpy(iv, &source[0], sizeof(iv));

      source.erase(0, sizeof(iv));

      

      dest.clear();

      try

      {

        CBC_Mode<Blowfish>::Decryption d;

        d.SetKeyWithIV(reinterpret_cast<const byte*>(key.c_str()), key.length(), iv);

        

        StringSource(source, true,

            new StreamTransformationFilter(d,

                new StringSink(dest)

            )

        );

      }

      catch (const Exception& e)

      {

        return false;

      }

       

      return true;

    }  

The crypto++ based encrypt / decrypt functions work fine with eachother. If I attempt to encrypt the same message as in the perl script with the same key and iv, the result is different.

Any help much appreciated!

Troy

[Troy]

Please disregard this, I've made a glaring error in the perl script omitting the -cipher option, no idea what it uses for default.