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#include <string>
#include <memory>
#include <sstream>
#include <iostream>
#include <stdexcept>
#include <botan/botan.h>
#include <botan/filters.h>
#include <botan/eax.h>
using namespace Botan;
/**
Encrypt and decrypt small rows
*/
class Row_Encryptor
{
public:
Row_Encryptor(const std::string& passphrase,
RandomNumberGenerator& rng);
Row_Encryptor(const std::string& passphrase,
const MemoryRegion<byte>& salt);
std::string encrypt(const std::string& input,
const MemoryRegion<byte>& salt);
std::string decrypt(const std::string& input,
const MemoryRegion<byte>& salt);
SecureVector<byte> get_s2k_salt() const { return s2k_salt; }
private:
void init(const std::string& passphrase);
Row_Encryptor(const Row_Encryptor&) {}
Row_Encryptor& operator=(const Row_Encryptor&) { return (*this); }
SecureVector<byte> s2k_salt;
Pipe enc_pipe, dec_pipe;
EAX_Encryption* eax_enc; // owned by enc_pipe
EAX_Decryption* eax_dec; // owned by dec_pipe;
};
Row_Encryptor::Row_Encryptor(const std::string& passphrase,
RandomNumberGenerator& rng)
{
s2k_salt.resize(10); // 80 bits
rng.randomize(&s2k_salt[0], s2k_salt.size());
init(passphrase);
}
Row_Encryptor::Row_Encryptor(const std::string& passphrase,
const MemoryRegion<byte>& salt)
{
s2k_salt = salt;
init(passphrase);
}
void Row_Encryptor::init(const std::string& passphrase)
{
std::auto_ptr<S2K> s2k(get_s2k("PBKDF2(SHA-160)"));
s2k->set_iterations(10000);
s2k->change_salt(&s2k_salt[0], s2k_salt.size());
SecureVector<byte> key = s2k->derive_key(32, passphrase).bits_of();
/*
Save pointers to the EAX objects so we can change the IV as needed
*/
Algorithm_Factory& af = global_state().algorithm_factory();
const BlockCipher* proto = af.prototype_block_cipher("Serpent");
if(!proto)
throw std::runtime_error("Could not get a Serpent proto object");
enc_pipe.append(eax_enc = new EAX_Encryption(proto->clone()));
dec_pipe.append(eax_dec = new EAX_Decryption(proto->clone()));
eax_enc->set_key(key);
eax_dec->set_key(key);
}
std::string Row_Encryptor::encrypt(const std::string& input,
const MemoryRegion<byte>& salt)
{
eax_enc->set_iv(salt);
enc_pipe.process_msg(input);
return enc_pipe.read_all_as_string(Pipe::LAST_MESSAGE);
}
std::string Row_Encryptor::decrypt(const std::string& input,
const MemoryRegion<byte>& salt)
{
eax_dec->set_iv(salt);
dec_pipe.process_msg(input);
return dec_pipe.read_all_as_string(Pipe::LAST_MESSAGE);
}
/*************************
Test code follows:
*/
int main()
{
Botan::LibraryInitializer init;
AutoSeeded_RNG rng;
const std::string secret_passphrase = "secret passphrase";
Row_Encryptor encryptor("secret passphrase", rng);
std::vector<std::string> original_inputs;
for(u32bit i = 0; i != 50000; ++i)
{
std::ostringstream out;
u32bit output_bytes = rng.next_byte();
for(u32bit j = 0; j != output_bytes; ++j)
out << std::hex << (int)rng.next_byte();
original_inputs.push_back(out.str());
}
std::vector<std::string> encrypted_values;
MemoryVector<byte> salt(4); // keep out of loop to avoid excessive dynamic allocation
for(u32bit i = 0; i != original_inputs.size(); ++i)
{
std::string input = original_inputs[i];
for(u32bit j = 0; j != 4; ++j)
salt[j] = (i >> 8) & 0xFF;
encrypted_values.push_back(encryptor.encrypt(input, salt));
}
for(u32bit i = 0; i != encrypted_values.size(); ++i)
{
std::string ciphertext = encrypted_values[i];
// NOTE: same salt value as previous loop (index value)
for(u32bit j = 0; j != 4; ++j)
salt[j] = (i >> 8) & 0xFF;
std::string output = encryptor.decrypt(ciphertext, salt);
if(output != original_inputs[i])
std::cout << "BOOM " << i << "\n";
}
Row_Encryptor test_s2k_salt_copy(secret_passphrase,
encryptor.get_s2k_salt());
salt.clear(); // all-0
std::string test = test_s2k_salt_copy.decrypt(encrypted_values[0], salt);
if(test != original_inputs[0])
std::cout << "S2K salt copy failed to decrypt properly\n";
return 0;
}
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