pp_unlock.cpp

#include <fstream>
#include <boost/filesystem.hpp>
#include <boost/lexical_cast.hpp>
#include <bitcoin/bitcoin.hpp>
#include "aes256.h"
using namespace bc;
namespace fs = boost::filesystem;

typedef std::vector<ec_point> ec_point_list;

payment_address bidding_address(const ec_point& pubkey)
{
    data_chunk data(pubkey.begin(), pubkey.end());
    payment_address payaddr;
    set_public_key(payaddr, data);
    return payaddr;
}
hash_digest derive_seed(const ec_point& pubkey)
{
    data_chunk data(pubkey.begin(), pubkey.end());
    return bitcoin_hash(data);
}

int main(int argc, char** argv)
{
    if (argc != 4)
    {
        std::cerr << "Usage: pp_unlock CHUNKFILE BLOCK_HASH PUBKEY"
            << std::endl;
        return -1;
    }
    const std::string chunk_filename = argv[1];
    const data_chunk hash = decode_hex(argv[2]);
    if (hash.empty() || hash.size() != hash_size)
    {
        std::cerr << "pp_unlock: not a valid BLOCK_HASH." << std::endl;
        return -1;
    }
    const ec_point pubkey = decode_hex(argv[3]);
    if (pubkey.empty() || pubkey.size() != ec_compressed_size)
    {
        std::cerr << "pp_unlock: not a valid PUBKEY." << std::endl;
        return -1;
    }
    std::ifstream infile(chunk_filename, std::ifstream::binary);
    infile.seekg(0, std::ifstream::end);
    size_t file_size = infile.tellg();
    BITCOIN_ASSERT(file_size % 16 == 0);
    infile.seekg(0, std::ifstream::beg);
    // Read entire file in.
    data_chunk cipher(file_size);
    // Copy chunk to public chunk file.
    char* data = reinterpret_cast<char*>(cipher.data());
    infile.read(data, file_size);
    infile.close();
    // Get seed.
    payment_address bid_addr = bidding_address(pubkey);
    hash_digest seed = derive_seed(pubkey);
    // Decrypt chunk.
    aes256_context ctx; 
    BITCOIN_ASSERT(seed.size() == 32);
    aes256_init(&ctx, seed.data());
    BITCOIN_ASSERT(cipher.size() % 16 == 0);
    for (size_t i = 0; i < cipher.size(); i += 16)
        aes256_decrypt_ecb(&ctx, cipher.data() + i);
    aes256_done(&ctx);
    // Write out.
    const fs::path new_chunk_filename = (chunk_filename + ".decrypted");
    std::ofstream outfile(new_chunk_filename.native(), std::ifstream::binary);
    char* dec_data = reinterpret_cast<char*>(cipher.data());
    outfile.write(dec_data, cipher.size());
    return 0;
}