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我已经为Crypto++ v5.6.2实施了一个C++包装库，并且有一个关于对称算法（例如Blowfish）和块模式（例如GCM）组合的问题。加密++对称算法和经过身份验证的块模式组合
我能够通过Blowfish/EAX加密和解密数据，但我无法通过使用Blowfish/GCM来实现同样的效果。 AES/EAX和AES/GCM都可以工作。
下面这个简单的应用程序演示了我的问题：
#include <iostream>
#include <string>
#include "cryptopp/blowfish.h"
#include "cryptopp/filters.h"
#include "cryptopp/eax.h"
#include "cryptopp/gcm.h"
#include "cryptopp/osrng.h"
#include "cryptopp/hex.h"
std::string encrypt(
CryptoPP::AuthenticatedSymmetricCipher &encryption,
std::string const kPlainText,
CryptoPP::SecByteBlock const kKey,
unsigned const char * kIV) {
std::string cipher_text;
// TODO Is this the source of the problem?
// BlockSize always returns 0 which leads to an exception if GCM block mode is used!
std::cout << encryption.BlockSize() << " bytes" << std::endl;
encryption.SetKeyWithIV(
kKey,
kKey.size(),
kIV
);
CryptoPP::StringSink *string_sink = new CryptoPP::StringSink(cipher_text);
CryptoPP::BufferedTransformation *transformator = NULL;
// The AuthenticatedEncryptionFilter adds padding as required.
transformator = new CryptoPP::AuthenticatedEncryptionFilter(
encryption,
string_sink);
bool const kPumpAll = true;
CryptoPP::StringSource(
kPlainText,
kPumpAll,
transformator);
return cipher_text;
}
std::string decrypt(
CryptoPP::AuthenticatedSymmetricCipher &decryption,
std::string const kCipherText,
CryptoPP::SecByteBlock const kKey,
unsigned const char * kIV) {
std::string recovered_plain_text;
decryption.SetKeyWithIV(
kKey,
kKey.size(),
kIV);
CryptoPP::StringSink *string_sink = new CryptoPP::StringSink(
recovered_plain_text);
CryptoPP::BufferedTransformation *transformator = NULL;
CryptoPP::AuthenticatedDecryptionFilter *decryption_filter = NULL;
decryption_filter = new CryptoPP::AuthenticatedDecryptionFilter(
decryption,
string_sink);
transformator = new CryptoPP::Redirector(*decryption_filter);
bool const kPumpAll = true;
CryptoPP::StringSource(
kCipherText,
kPumpAll,
transformator);
return recovered_plain_text;
}
int main() {
CryptoPP::AutoSeededRandomPool prng;
CryptoPP::SecByteBlock key(CryptoPP::Blowfish::DEFAULT_KEYLENGTH);
prng.GenerateBlock(key, key.size());
byte iv[CryptoPP::Blowfish::BLOCKSIZE];
prng.GenerateBlock(iv, sizeof(iv));
// Creates templated mode objects of block ciphers.
// This works...
// CryptoPP::EAX<CryptoPP::Blowfish>::Encryption encryption;
// CryptoPP::EAX<CryptoPP::Blowfish>::Decryption decryption;
// This does NOT work...
CryptoPP::GCM<CryptoPP::Blowfish>::Encryption encryption;
CryptoPP::GCM<CryptoPP::Blowfish>::Decryption decryption;
std::string plain_text = "Block Mode Test";
std::string cipher_text = encrypt(encryption, plain_text, key, iv);
// terminate called after throwing an instance of 'CryptoPP::InvalidArgument'
// what(): Blowfish/GCM: block size of underlying block cipher is not 16
std::cout << "cipher text: " << std::hex << cipher_text << std::endl;
std::cout << "recovered plain text: " << decrypt(decryption, cipher_text, key, iv) << std::endl;
}
一个CryptoPP::InvalidArgument异常被抛出，如果运行上面下面的文本代码：
Blowfish/GCM: block size of underlying block cipher is not 16
但随着块运行代码的时候，而不是模式EAX，不会引发异常。所以我的问题是：
- 是否GCM只适用于AES？ GCM也可以与Blowfish或3DES一起使用吗？
- 是否有可用的矩阵列出了对称算法与块模式的所有可能组合？
- 或者这是Crypto ++中的错误吗？因为方法
BlockSize()总是返回0但是只有在使用Blowfish（或3DES）而不是AES时才会引发异常。这似乎引起了所提到的例外。