Decrypt file using AES::CBC

[Rash]

Hello All,
  Following are my specifications to encrypt/decrypt files using
AES::CBC mode

Encrypt process:
1) 8 bytes random IV ( Initialization Vector ).
   Insert the 8 bytes random IV to the beginning of the data stream.

2) Key length with 16 bytes ( digest using MD5 ).
3) padding method compatible with RFC 2898.
4) Encrypt the file.

Decrypt process:
1) Read the first 8 bytes block and ignore it.
2) Digest the key using MD5.
3) Use the same padding method used when encrypting the file.
4) Decrypt the file.

To encrypt the file here is my code
void encryptFile(const char* password, const char* inputFileName,
const
char* outputFileName)
{
    byte pass[ AES::BLOCKSIZE ];        // digest of password
    byte iv[ 8 ];               // Initial Vector (IV)

    AutoSeededRandomPool rng;           // random number generator
        try
        {
                // digest password
                StringSource( password, true,new HashFilter(*(new MD5), new
                                ArraySink(pass, AES::BLOCKSIZE)) );

                // random Initial Vector
                rng.GenerateBlock(iv, 8);

                // create object for encrypting
                AES::Encryption aesEncryption(pass,
CryptoPP::AES::DEFAULT_KEYLENGTH);
                CBC_Mode_ExternalCipher::Encryption cbcEncryption(aesEncryption,
iv);

                StreamTransformationFilter *encryptor;
                encryptor = new StreamTransformationFilter(cbcEncryption, new
FileSink(outputFileName) );

                encryptor->Put(iv, 8);

                // "bind" a file and encrypt one
                FileSource(inputFileName, true, encryptor);
        }
        catch(CryptoPP::Exception &e)
        {
                return;
        }
}
void decryptFile(const char* password, const char*inputFileName,const
char*outputFileName)
{
   //help me to write the decrypt functionality
}

How do I decrypt the file? I'm unable to read the first 8 bytes block
and ignore it.
Please help me to write the decrypt function satisfying the above
specifications.

Thanks in advance


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