我正在运行Crypto ++对加密算法进行速度测试。我试图计算加密，然后解密数据需要多长时间（最终有更多的文件大小和不同的算法）。我遇到了一个无法循环代码的问题。在下面的代码中，我使用的是Blowfish，但是当我到达加密部分时，它给了我错误：
HashVerificationFilter: message hash or MAC not valid
我该怎么做才能解决这个问题？我需要把它放在一个函数中吗？如果是这样，我该怎么做？
/**
* g++ encryption_tests.cpp -o encryption_tests -lcryptopp -lpthread -L.
*/
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
#include <ctime>
#include "cryptoplusplus/osrng.h"
using CryptoPP::AutoSeededRandomPool;
#include "cryptoplusplus/cryptlib.h"
using CryptoPP::Exception;
#include "cryptoplusplus/hex.h"
using CryptoPP::HexEncoder;
using CryptoPP::HexDecoder;
#include "cryptoplusplus/modes.h"
#include "cryptoplusplus/aes.h"
#include "cryptoplusplus/filters.h"
using CryptoPP::StringSink;
using CryptoPP::StringSource;
using CryptoPP::AuthenticatedEncryptionFilter;
using CryptoPP::AuthenticatedDecryptionFilter;
using namespace std;
#include "cryptoplusplus/filters.h"
using CryptoPP::StringSink;
using CryptoPP::StringSource;
using CryptoPP::AuthenticatedEncryptionFilter;
using CryptoPP::AuthenticatedDecryptionFilter;
#include "cryptoplusplus/blowfish.h"
using CryptoPP::Blowfish;
#include "crypto++/eax.h"
using CryptoPP::EAX;
#include "cryptoplusplus/secblock.h"
using CryptoPP::SecByteBlock;
int main( int argc, char* argv[] ) {
// Declaring variables
const int NUMBER_OF_RUNS = 3;
const int NUMBER_OF_TXT_FILES = 9;
const int NUMBER_OF_JPG_FILES = 6;
const int NUMBER_OF_PNG_FILES = 6;
const int NUMBER_OF_AVI_FILES = 2;
string file_names_txt[NUMBER_OF_TXT_FILES] = { "10B.txt", "100B.txt", "1KB.txt", "10KB.txt", "100KB.txt", "1MB.txt", "5MB.txt", "10MB.txt", "20MB.txt" };
string file_names_jpg[NUMBER_OF_JPG_FILES] = { "1KB.jpg", "10KB.jpg", "100KB.jpg", "1MB.jpg", "3MB.jpg", "5MB.jpg" };
string file_names_png[NUMBER_OF_PNG_FILES] = { "100B.png", "500B.png","1KB.png", "10KB.png","1MB.png", "5MB.png" };
string file_names_avi[NUMBER_OF_AVI_FILES] = { "4MB.avi", "10MB.avi" };
int time_data [NUMBER_OF_RUNS];
string plaintext, cipher, encoded, recovered, sample_files_path, data_file, line_contents;
string initial_cpp_time_data = "";
clock_t time_start, time_stop;
double run_time, time_difference, time_average = 0;
// This loop will run the test NUMBER_OF_RUNS times
for ( int i = 0 ; i < NUMBER_OF_RUNS ; i++ ) {
time_start = clock();
// This class seeds itself using an operating system provided RNG
AutoSeededRandomPool prng;
// Generate a random key
SecByteBlock key(Blowfish::DEFAULT_KEYLENGTH);
prng.GenerateBlock(key, key.size());
// Generate a random initialization vector
byte iv[Blowfish::BLOCKSIZE];
prng.GenerateBlock(iv, sizeof(iv));
// Set key width
EAX< Blowfish >::Encryption e;
e.SetKeyWithIV(key, key.size(), iv);
// Grab the data from the file we want to run the test on
sample_files_path = "sample_files/" + file_names_txt[8];
ifstream initial_file_contents ( sample_files_path.c_str() );
if (initial_file_contents.is_open()) {
while ( getline( initial_file_contents, line_contents ) ) {
plaintext = plaintext + line_contents;
plaintext.push_back('\n');
initial_file_contents.close();
}
} else {
cout << "Unable to open file" << endl;
}
// Encrypts the plaintext
try {
StringSource(plaintext, true, new AuthenticatedEncryptionFilter(e, new StringSink(cipher) ) );
} catch ( const CryptoPP::Exception& e ) {
cerr << e.what() << endl;
exit(1);
}
// Decrypts the test
try {
EAX< Blowfish >::Decryption d;
d.SetKeyWithIV(key, key.size(), iv);
StringSource s(cipher, true, new AuthenticatedDecryptionFilter( d, new StringSink(recovered) ) );
} catch ( const CryptoPP::Exception& e ) {
cerr << e.what() << endl;
exit(1);
}
// Stop the clock, calculate the time difference, turn to milliseconds
time_stop = clock();
time_difference = time_stop - time_start;
run_time = time_difference / ( CLOCKS_PER_SEC / 1000 );
time_data[i] = run_time;
cout << "time_data[" << i << "]: " << time_data[i] << " milliseconds" << endl;
}
//Grab the data from the old file
ifstream initial_cpp_time_data_file ( "cpp_time_data.txt" );
if (initial_cpp_time_data_file.is_open()) {
while ( getline( initial_cpp_time_data_file, line_contents ) ) {
initial_cpp_time_data = initial_cpp_time_data + line_contents;
initial_cpp_time_data.push_back('\n');
}
initial_cpp_time_data_file.close();
} else {
initial_cpp_time_data = "";
}
// Created a new file
ofstream time_data_file;
time_data_file.open("cpp_time_data.txt");
// Insert old data first
time_data_file << initial_cpp_time_data << endl;
// Show the file the test ran on and insert the new data
time_data_file << sample_files_path << endl;
for ( int i = 0 ; i < NUMBER_OF_RUNS ; i++ ) {
time_data_file << "time_data[" << i << "]: " << time_data[i] << " milliseconds" << endl;
time_average = time_average + time_data[i];
}
time_average = time_average / NUMBER_OF_RUNS;
time_data_file << "The average time for this is " << time_average << " milliseconds" << endl;
cout << "The average time for this is " << time_average << " milliseconds" << endl;
time_data_file.close();
cout << "Done!\n";
return 0;
}
答案 0 :(得分：2)
在循环的每次迭代中，您必须调用：
cipher.clear() recovered.clear() 否则，StringSink只会继续添加到上一个值的末尾。你将在循环的第二次和后续迭代中失败（第一次应该没问题）。
此外，没有Resynchronize，因此您无法调用e.Resynchronize(iv)重新启动密码。你必须在循环的每次迭代中调用e.SetKeyWithIV(key, key.size(), iv)。
下面，我无法复制您的重用问题。加密对象被重用，而解密对象是为每次迭代创建的。运行程序的结果：
$ ./cryptopp-test.exe
plain text: String 1
recovered text: String 1
plain text: String 2
recovered text: String 2
plain text: String 3
recovered text: String 3
plain text: String 4
recovered text: String 4
plain text: String 5
recovered text: String 5
AutoSeededRandomPool prng;
SecByteBlock key(Blowfish::DEFAULT_KEYLENGTH);
prng.GenerateBlock( key, key.size() );
byte iv[ Blowfish::BLOCKSIZE ];
prng.GenerateBlock( iv, sizeof(iv) );
vector<string> vv;
vv.push_back("String 1");
vv.push_back("String 2");
vv.push_back("String 3");
vv.push_back("String 4");
vv.push_back("String 5");
string plain, cipher, recovered;
try {
EAX< Blowfish >::Encryption e1;
e1.SetKeyWithIV( key, key.size(), iv, sizeof(iv) );
for(unsigned i = 0; i < vv.size(); i++)
{
/*********************************\
\*********************************/
plain = vv[i];
cout << "plain text: " << plain << endl;
e1.SetKeyWithIV( key, key.size(), iv, sizeof(iv) );
cipher.clear();
StringSource ss1(plain, true,
new AuthenticatedEncryptionFilter( e1,
new StringSink( cipher )
) ); // StringSource
/*********************************\
\*********************************/
EAX< Blowfish >::Decryption d2;
d2.SetKeyWithIV( key, key.size(), iv, sizeof(iv) );
recovered.clear();
StringSource ss2(cipher, true,
new AuthenticatedDecryptionFilter( d2,
new StringSink( recovered ),
AuthenticatedDecryptionFilter::THROW_EXCEPTION
) ); // StringSource
cout << "recovered text: " << recovered << endl;
}
} catch (const Exception& ex) {
cerr << ex.what() << endl;
}