grimreaper, We can probably help you on this list, but you'll need to provide more information than this. The code that was provided ought to work equally well for text and binary, so let's try to figure out what's wrong with your example.
In what way does decryption fail? Does it throw an exception? What exception? Does it produce a corrupt file? In what way is the file corrupt? (That is, in what way is it different from the original file?) Does it have its CR's replaced with CRLF's? Does it have null bytes removed? Is it the same size or a different size? Does it have random junk at the beginning or end? Does it fail in the same way every time, or does it depend on the random "IV" block? Does the output file just have the wrong extension (.txt) for your OS to open it? What OS are you running (Windows, right? What version?), and what version of Crypto++? Cheers, Mike On Fri, 2010-09-10 at 00:45 -0700, grimreaper wrote: > > > Mouse-2 wrote: > > > > > > > > > > #include <iostream> > > > > #include <cryptopp/aes.h> > > #include <cryptopp/modes.h> > > #include <cryptopp/sha.h> > > #include <cryptopp/osrng.h> > > #include <cryptopp/files.h> > > #include <cryptopp/filters.h> > > > > USING_NAMESPACE(CryptoPP); > > USING_NAMESPACE(std); > > > > /**************************************************************/ > > /* Code to illustrate usage of cryptographic primitives */ > > /* provided by Crypto++ library v5.5.1 of Wei Dai. */ > > /* */ > > /* In particular, the program provides two functions: */ > > /* */ > > /* 1. Encrypt a file (key based on password) with random IV;*/ > > /* */ > > /* 2. Decrypt previously encrypted file. */ > > /* */ > > /* Issue with the original code: */ > > /* - set IV in the encryptor but also used it as random */ > > /* prefix, so garbage was the 1st encrypted block; */ > > /* - did not "fast-forward" the encrypted file past the */ > > /* first block (which was encrypted random garbage). */ > > /* */ > > /* Corrections performed: */ > > /* - fixed encryptor by leaving random block prefixed, */ > > /* but removing redundancy (having it in encryptor); */ > > /* - fixed decryptor (see the source code). */ > > /* */ > > /*==========================================================*/ > > /* Written by: */ > > /* Rash <[email protected]> */ > > /* */ > > /* Modified by: */ > > /* Mouse <[email protected]> */ > > /* Sun Sep 2, 12:25:00 2007 */ > > /* */ > > /************************************************************/ > > /* */ > > /* Copyright (C) 2007 Rash <[email protected]> */ > > /* Copyright (C) 2007 Mouse <[email protected]> */ > > /* */ > > /************************************************************/ > > > > void encryptFile(const char* password, const char* inputFileName, > > const char* outputFileName) > > { > > byte pass[AES::BLOCKSIZE]; // digest of password > > byte iv[16]; // Initial Vector (IV), misused > > // by original author > > byte true_iv[16]; // real IV used - set to zero > > > > AutoSeededRandomPool rng; > > > > // digest password > > StringSource(password, true, > > new HashFilter(*(new SHA256), > > new ArraySink(pass, AES::BLOCKSIZE))); > > > > // random Initial Vector > > rng.GenerateBlock(iv, 16); > > memset(true_iv, 0, 16); > > > > // create object for encrypting > > AES::Encryption aesEncryption(pass, > > CryptoPP::AES::DEFAULT_KEYLENGTH); > > CBC_Mode_ExternalCipher::Encryption cbcEncryption(aesEncryption, > > true_iv); > > > > StreamTransformationFilter *encryptor; > > encryptor = new StreamTransformationFilter(cbcEncryption, > > new FileSink(outputFileName) ); > > > > encryptor->Put(iv, 16); // this prefixes the file with random block (not > > IV) > > // Cryptographically it is equivalent to IV, so just as > > good > > > > // "bind" a file and encrypt one > > FileSource(inputFileName, true, encryptor); > > } > > > > > > void decryptFile(const char* password, const char*inputFileName, > > const char* outputFileName) > > { > > byte pass[AES::BLOCKSIZE]; > > byte iv[16]; // here's 1st problem: AES IV is 16 bytes > > byte head_file[16]; // so must skip 16 bytes, not 8. > > > > memset(iv, 0, 16); // very correct - in fact the encryptor prefixes file > > // with a random block, so no need to pass the IV explicitly. > > > > try { > > StringSource(password, true, new HashFilter(*(new SHA256), new > > > > ArraySink(pass,AES::BLOCKSIZE))); > > > > CryptoPP::AES::Decryption aesDecryption(pass, > > CryptoPP::AES::DEFAULT_KEYLENGTH); > > CryptoPP::CBC_Mode_ExternalCipher::Decryption > > cbcDecryption(aesDecryption, iv); > > > > StreamTransformationFilter *decryptor; > > decryptor = new > > StreamTransformationFilter(cbcDecryption, new > > FileSink(outputFileName)); > > > > > > // decryptor->Get(head_file, 16); // does not do anything useful, > > wrong here > > // We must somehow decrypt 1st block of the input file, without > > sending the > > // result into the output file. > > char garbage[16], iv_garbage[16]; // place for IV stuff > > ifstream inf; > > inf.open(inputFileName); inf.read(iv_garbage, 16); // absorb random > > prefix > > > > // Decrypt random prefix (with zero IV) to some dummy buffer to get > > // (a) decryptor state adjusted to IV, and > > // (b) file position pointer advanced to the past-IV spot. > > cbcDecryption.ProcessData((byte *)garbage, (const byte *)iv_garbage, > > 16); > > > > // NOW can run the decryption engine in "automatic" mode > > FileSource(inf, true, decryptor); > > > > inf.close(); // to be nice > > } > > catch(CryptoPP::Exception &e) > > { > > cerr << "Caught exception during decryption!" << endl; > > return; > > } > > } > > > > int main(int argc, char *argv[]) > > { > > const char *pwd = "not-so-complicated parole"; > > const char *pfn = "plain.txt"; > > const char *cfn = "cipher.dat"; > > const char *ofn = "plain2.txt"; > > > > // Create test plaintext file "plain.txt" > > ofstream plain; > > plain.open(pfn); > > plain << "An excellent test of file encryption techniques.\n"; > > plain << "This test will not demonstrate many tricks though.\n"; > > plain.close(); > > > > // Invoke encryptor to encrypt into "cipher.dat" > > encryptFile(pwd, pfn, cfn); > > > > // Invoke decryptor to decrypt into "plain2.txt" > > decryptFile(pwd, cfn, ofn); > > > > exit(0); > > } > > > > > > > your code is working on text but when i used a binary file like an image it > failed > please help > what changes should i make > please reply > thanks in advance > -- > View this message in context: > http://old.nabble.com/Decrypt-file-using-AES%3A%3ACBC-tp12446523p29674413.html > Sent from the Crypto++ Users mailing list archive at Nabble.com. > -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. 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