libcryfs/implementations/encrypted/ciphers/CFB_Cipher.h
2015-08-31 23:04:56 +02:00

64 lines
2.4 KiB
C++

#pragma once
#ifndef MESSMER_BLOCKSTORE_IMPLEMENTATIONS_ENCRYPTED_CIPHERS_AES256_CFB_H_
#define MESSMER_BLOCKSTORE_IMPLEMENTATIONS_ENCRYPTED_CIPHERS_AES256_CFB_H_
#include <messmer/cpp-utils/data/FixedSizeData.h>
#include <messmer/cpp-utils/data/Data.h>
#include <boost/optional.hpp>
#include <cryptopp/cryptopp/modes.h>
#include "Cipher.h"
namespace blockstore {
namespace encrypted {
template<typename BlockCipher, unsigned int KeySize>
class CFB_Cipher {
public:
BOOST_CONCEPT_ASSERT((CipherConcept<CFB_Cipher<BlockCipher, KeySize>>));
using EncryptionKey = cpputils::FixedSizeData<KeySize>;
static constexpr unsigned int ciphertextSize(unsigned int plaintextBlockSize) {
return plaintextBlockSize + IV_SIZE;
}
static constexpr unsigned int plaintextSize(unsigned int ciphertextBlockSize) {
return ciphertextBlockSize - IV_SIZE;
}
static cpputils::Data encrypt(const byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey);
static boost::optional<cpputils::Data> decrypt(const byte *ciphertext, unsigned int ciphertextSize, const EncryptionKey &encKey);
private:
static constexpr unsigned int IV_SIZE = BlockCipher::BLOCKSIZE;
};
template<typename BlockCipher, unsigned int KeySize>
cpputils::Data CFB_Cipher<BlockCipher, KeySize>::encrypt(const byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey) {
auto iv = cpputils::FixedSizeData<IV_SIZE>::CreatePseudoRandom();
auto encryption = typename CryptoPP::CFB_Mode<BlockCipher>::Encryption(encKey.data(), encKey.BINARY_LENGTH, iv.data());
cpputils::Data ciphertext(ciphertextSize(plaintextSize));
std::memcpy(ciphertext.data(), iv.data(), IV_SIZE);
encryption.ProcessData((byte*)ciphertext.data() + IV_SIZE, plaintext, plaintextSize);
return ciphertext;
}
template<typename BlockCipher, unsigned int KeySize>
boost::optional<cpputils::Data> CFB_Cipher<BlockCipher, KeySize>::decrypt(const byte *ciphertext, unsigned int ciphertextSize, const EncryptionKey &encKey) {
if (ciphertextSize < IV_SIZE) {
return boost::none;
}
const byte *ciphertextIV = ciphertext;
const byte *ciphertextData = ciphertext + IV_SIZE;
auto decryption = typename CryptoPP::CFB_Mode<BlockCipher>::Decryption((byte*)encKey.data(), encKey.BINARY_LENGTH, ciphertextIV);
cpputils::Data plaintext(plaintextSize(ciphertextSize));
decryption.ProcessData((byte*)plaintext.data(), ciphertextData, plaintext.size());
return std::move(plaintext);
}
}
}
#endif