RE: Gzip & Gunzip code: Correct or rubbish

[Walton, Jeffrey]

Hi Stephen,

> Is this right? So far I believe it does not because what I get in 
> 'unzip_text' is rubbish.
Probably not if you are getting rubbish.

Here's a non-elegant sample (I'm almost embarrassed to post it). Notice how
all the objects basically act the same. You can drop in a base64
(en/de)coder in place of the hex. That's one of the great benefits of using
this library. Sadly, I don't take advantage of chaining...

Jeff

BTW, sample code that we could compile would be nice next time.

#include "gzip.h"
#include "hex.h"

#include <iostream>
#include <string>

#pragma comment( lib, "cryptlibd" )

using std::string;
using std::cout;
using std::endl;

int main(int argc, char* argv[]) {

    string original("B  o  o     H  o  o     I     a  m     s  o     s  c  a
r  e  d");

    cout << "Original String:" << endl << original << endl << endl;

    ///////////////////////////
    //
    // Compress
    //
    CryptoPP::Gzip compressor;

    compressor.PutMessageEnd( (const byte*)original.c_str(), original.size()
);

    // Alternately
    //   compressor.Put( (const byte*)original.c_str(), original.size() );
    //   compressor.MessageEnd();

    byte* zip = NULL;
    int size = compressor.MaxRetrievable();

    zip = new byte[ size ];

    compressor.Get( zip, size );    
    
    ///////////////////////////
    //
    // Encode
    //
    CryptoPP::HexEncoder encoder;
    encoder.PutMessageEnd( zip, size );

    byte* hex = NULL;
    hex = new byte[ encoder.MaxRetrievable() + 1 ];
    hex[ encoder.MaxRetrievable() ] = '\0';
    
    encoder.Get( hex, encoder.MaxRetrievable() );
    
    cout << "Compressed String:" << endl << hex << endl << endl;

    ///////////////////////////
    //
    // Decode
    //

    // Would look like the rest of it.

    ///////////////////////////
    //
    // Decompress
    //
    CryptoPP::Gunzip decompressor;
    decompressor.PutMessageEnd( zip, size );

    string decompressed;
    decompressed.resize( decompressor.MaxRetrievable() + 1 );
    decompressed[ decompressor.MaxRetrievable() ] = '\0';

    decompressor.Get( (byte*)decompressed.c_str(),
decompressor.MaxRetrievable() );

    cout << "Decompressed String:" << endl << decompressed << endl << endl;

    if( NULL != zip ) {

        delete[] zip;
    }

    if( NULL != zip ) {

        delete[] hex;
    }

        return 0;
} 

> -----Original Message-----
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Stephen torri
> Sent: Tuesday, November 18, 2003 7:38 PM
> To: cryptopp
> Subject: Gzip & Gunzip code: Correct or rubbish
> 
> 
> I decided to work on get my encrypt and decrypt methods in 
> stages. The first stage is to get the plain text string 
> compressed and decompressed correctly.
> 
> Gcc:3.2.3
> Crypto:5.1
> 
> Compress:
> 
> string gzip_text;
> Gzip aes_compressor2 (new StringSink (gzip_text)); 
> StringStore(plaintext).TransferTo(aes_compressor2);
> 
> string unzip_text;
> Gunzip aes_decompressor2 (new StringSink (unzip_text)); 
> StringStore(gzip_text).TransferTo(aes_decompressor2);
> 
> I got this from searching the archive of the mailing list. 
> Shame we do not have a directory of example programs. Is this 
> right? So far I believe it does not because what I get in 
> 'unzip_text' is rubbish.
> 
> Plaintext char:  B  o  o     H  o  o     I     a  m     s  o     s  c 
> a  r  e  d
> Plaintext hex:  0x42  0x6f  0x6f  0x20  0x48  0x6f  0x6f  0x20  0x49 
> 0x20  0x61  0x6d  0x20  0x73  0x6f  0x20  0x73  0x63  0x61  
> 0x72  0x65 
> 0x64
> 
> <OUTPUT: Compress plain text>
> Compressed text2:  0x1f  0xffffff8b  0x8  0  0  0  0  0  0  0
> 
> <OUTPUT: Decompressed plain text>
> Decompressed text2:
> 
> Stephen
>