mirror of
https://github.com/AGWA/git-crypt.git
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82 lines
2.7 KiB
C++
82 lines
2.7 KiB
C++
/*
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* Copyright 2012, 2014 Andrew Ayer
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*
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* This file is part of git-crypt.
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*
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* git-crypt is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* git-crypt is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with git-crypt. If not, see <http://www.gnu.org/licenses/>.
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*
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* Additional permission under GNU GPL version 3 section 7:
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*
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* If you modify the Program, or any covered work, by linking or
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* combining it with the OpenSSL project's OpenSSL library (or a
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* modified version of that library), containing parts covered by the
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* terms of the OpenSSL or SSLeay licenses, the licensors of the Program
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* grant you additional permission to convey the resulting work.
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* Corresponding Source for a non-source form of such a combination
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* shall include the source code for the parts of OpenSSL used as well
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* as that of the covered work.
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*/
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#include "crypto.hpp"
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#include "util.hpp"
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#include <cstring>
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Aes_ctr_encryptor::Aes_ctr_encryptor (const unsigned char* raw_key, const unsigned char* nonce)
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: ecb(raw_key)
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{
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// Set first 12 bytes of the CTR value to the nonce.
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// This stays the same for the entirety of this object's lifetime.
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std::memcpy(ctr_value, nonce, NONCE_LEN);
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byte_counter = 0;
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}
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Aes_ctr_encryptor::~Aes_ctr_encryptor ()
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{
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explicit_memset(pad, '\0', BLOCK_LEN);
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}
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void Aes_ctr_encryptor::process (const unsigned char* in, unsigned char* out, size_t len)
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{
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for (size_t i = 0; i < len; ++i) {
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if (byte_counter % BLOCK_LEN == 0) {
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// Set last 4 bytes of CTR to the (big-endian) block number (sequentially increasing with each block)
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store_be32(ctr_value + NONCE_LEN, byte_counter / BLOCK_LEN);
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// Generate a new pad
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ecb.encrypt(ctr_value, pad);
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}
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// encrypt one byte
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out[i] = in[i] ^ pad[byte_counter++ % BLOCK_LEN];
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if (byte_counter == 0) {
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throw Crypto_error("Aes_ctr_encryptor::process", "Too much data to encrypt securely");
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}
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}
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}
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// Encrypt/decrypt an entire input stream, writing to the given output stream
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void Aes_ctr_encryptor::process_stream (std::istream& in, std::ostream& out, const unsigned char* key, const unsigned char* nonce)
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{
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Aes_ctr_encryptor aes(key, nonce);
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unsigned char buffer[1024];
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while (in) {
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in.read(reinterpret_cast<char*>(buffer), sizeof(buffer));
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aes.process(buffer, buffer, in.gcount());
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out.write(reinterpret_cast<char*>(buffer), in.gcount());
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}
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}
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