mirror of
https://github.com/biergaizi/codecrypt
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476 lines
14 KiB
C++
476 lines
14 KiB
C++
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/*
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* This file is part of Codecrypt.
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*
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* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
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*
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* Codecrypt is free software: you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or (at
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* your option) any later version.
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*
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* Codecrypt is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Codecrypt. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "algos_enc.h"
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#include "mce_qcmdpc.h"
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#include "arcfour.h"
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#include "chacha.h"
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#include "xsynd.h"
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#if HAVE_CRYPTOPP==1
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#include "sha_hash.h"
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#include "rmd_hash.h"
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#endif
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#include "cube_hash.h"
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typedef arcfour<byte, 8, 4096> arcfour_fo_cipher;
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/*
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* keygen
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*/
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template<int bs, int bc, int wi, int t, int rounds, int delta>
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static int mceqcmdpc_create_keypair (sencode**pub, sencode**priv, prng&rng)
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{
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mce_qcmdpc::pubkey Pub;
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mce_qcmdpc::privkey Priv;
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if (mce_qcmdpc::generate (Pub, Priv, rng, bs, bc, wi, t, rounds, delta))
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return 1;
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*pub = Pub.serialize();
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*priv = Priv.serialize();
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return 0;
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}
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/*
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* Padding. Ha-ha.
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*
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* This wouldn't be necessary, but the ciphertext length would then very easily
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* leak information about plaintext length (= len(c) - len(McE block) ).
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* Moreover we need to somehow convert bvector bits to actual bytes.
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*
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* First, the bvector is converted to vector of bytes so it's easy to work with
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* it. Result is in the form
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*
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* bits [randombits] nrbits
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*
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* where
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* bits = message bits
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* randombits = randomness that pads the message bits to whole byte.
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* nrbits = 1 byte with number of random bits applied
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*
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* Then we are padding stuff with a padding of length at most 255 blocks, from
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* both sides:
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*
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* 1bytesize [randomrandom] messagemessage [randomrandomrandom] 1bytesize
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*
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* where
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* message = "tail" of the message that has overflown to the last block
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* random = random bytes
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* 1bytesize = how many bytes do corresponding random data have.
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*
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* Note that:
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* - the last block is _always present_
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* (even if there are no message bytes in it, there still must be the zero
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* 1byte number that is telling us.)
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* - stuff in bytes is always thought about as big-endian
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*
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* 1bytesize is determined from message and message length in bits, as:
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*
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* size_start = h1(msg) + h2(|msg|)
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* size_start = h3(msg) + h4(|msg|)
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*
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* where h1 to h4 are hash functions to [0..127]
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*/
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#include <stdint.h>
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#include "hash.h"
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static void msg_pad_length (const std::vector<byte>& msg,
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byte&start, byte&end,
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hash_func&pad_hash)
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{
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uint64_t len = msg.size();
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std::vector<byte> lenbytes;
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lenbytes.resize (sizeof (uint64_t), 0);
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for (uint i = 0; i < sizeof (uint64_t); ++i) {
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lenbytes[i] = len & 0xff;
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len >>= 8;
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}
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std::vector<byte> tmp;
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tmp = pad_hash (lenbytes);
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start = tmp[0] & 0x7f;
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end = tmp[1] & 0x7f;
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tmp = pad_hash (msg);
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start += tmp[0] & 0x7f;
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end += tmp[1] & 0x7f;
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}
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static void message_pad (const bvector&in, std::vector<byte>&out,
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prng&rng, hash_func&pad_hash)
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{
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in.to_bytes (out);
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//make space for the bit stage
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out.resize (out.size() + 1, 0);
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//pad with random bits to whole byte
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unsigned char rtmp = rng.random (256);
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uint i;
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for (i = in.size(); i & 0x7; ++i)
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if (rtmp >> (i & 0x7))
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out[i >> 3] |= 1 << (i & 0x7);
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//append message overflow size
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out[i >> 3] = in.size() & 0x7;
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//byte stage
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byte padsize_begin, padsize_end;
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msg_pad_length (out, padsize_begin, padsize_end, pad_hash);
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//padding at the beginning
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out.insert (out.begin(), 1 + (uint) padsize_begin, 0);
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out[0] = padsize_begin;
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for (i = 1; i <= padsize_begin; ++i)
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out[i] = rng.random (256);
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//tail padding
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uint out_end = out.size();
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out.resize (out_end + padsize_end + 1, 0);
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for (i = 0; i < padsize_end; ++i)
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out[out_end + i] = rng.random (256);
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out[out_end + padsize_end] = padsize_end;
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}
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static bool message_unpad (std::vector<byte> in, bvector&out,
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hash_func&pad_hash)
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{
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//check byte padding sizes
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if (!in.size()) return false;
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//get rid of the byte padding
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uint padsize_begin, padsize_end;
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padsize_begin = in[0];
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padsize_end = in[in.size() - 1];
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//check if it really fits
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//(2 bytes padding + 1 byte min padded msg length)
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if ( (uint) padsize_begin + (uint) padsize_end + 3 > in.size())
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return false;
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//get rid of beginning padding
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in.erase (in.begin(), in.begin() + 1 + (uint) padsize_begin);
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uint in_end = in.size() - padsize_end - 1;
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in.resize (in_end);
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/* check if padding was really okay. Note that it is not necessary
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* since the padded message is "already checked" for mangling by F-O
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* padding. This is only a check that sender uses the same valid
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* padding method as we do. */
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byte check_begin, check_end;
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msg_pad_length (in, check_begin, check_end, pad_hash);
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if (padsize_begin != check_begin || padsize_end != check_end)
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return false;
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//get bit padding information (now it's the last byte)
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uint bit_overflow = in[in_end - 1];
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//there must not be more than one byte of overflown bits
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if (bit_overflow >= 8) return false;
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//check if there's byte with overflow bits
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if (bit_overflow && (in_end < 2)) return false;
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//convert to bvector
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uint msg_size = ( (in_end - (bit_overflow ? 2 : 1)) << 3)
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+ bit_overflow;
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out.from_bytes (in, msg_size);
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return true;
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}
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/*
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* Fujisaki-okamoto part
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*/
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#define MIN(a,b) ((a)<(b)?(a):(b))
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/*
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* Generic F-O functions. Note that ranksize must be equal to
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*
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* floor(log(comb(ciphersize,errorcount))/log(2))
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*
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* otherwise it probably fails. miserably.
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*/
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template < class pubkey_type,
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int plainsize,
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int ciphersize,
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int errorcount,
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class hash_type,
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class pad_hash_type,
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class scipher,
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int ranksize >
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static int fo_encrypt (const bvector&plain, bvector&cipher,
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sencode* pubkey, prng&rng)
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{
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uint i;
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//load the key
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pubkey_type Pub;
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if (!Pub.unserialize (pubkey)) return 1;
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//verify that key parameters match our scheme
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if (Pub.plain_size() != plainsize) return 2;
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if (Pub.cipher_size() != ciphersize) return 3;
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if (Pub.error_count() != errorcount) return 4;
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//create the unencrypted message part
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std::vector<byte> M;
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pad_hash_type phf;
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message_pad (plain, M, rng, phf);
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//create the symmetric key
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std::vector<byte> K;
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K.resize (plainsize >> 3);
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for (i = 0; i < K.size(); ++i) K[i] = rng.random (256);
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if (plainsize & 7) { //the byte overlap
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K.resize (1 + (plainsize >> 3), 0);
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K[plainsize >> 3] = rng.random (256) % (1 << (uint) (plainsize & 7));
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}
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//create the base for error vector
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std::vector<byte> H, M2;
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M2 = M;
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M2.insert (M2.end(), K.begin(), K.end());
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hash_type hf;
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H = hf (M2);
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//prepare the error vector (rotate the hash so we don't need ultralong hash functions)
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bvector ev_rank;
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ev_rank.resize (ranksize, 0);
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for (i = 0; i < ranksize; ++i)
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ev_rank[i] = 1 & (H[ (i >> 3) % H.size()] >> (i & 0x7));
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bvector ev;
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ev_rank.colex_unrank (ev, ciphersize, errorcount);
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//prepare plaintext
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bvector mce_plain;
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mce_plain.from_bytes (K);
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mce_plain.resize (plainsize, 0); //fit to exact size (there shouldn't be overflow)
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//run McEliece
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if (Pub.encrypt (mce_plain, cipher, ev)) return 5;
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//encrypt the message part
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scipher sc;
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sc.init ();
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//whole key must be tossed in, so split if when necessary
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sc.load_key_vector (K);
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//encrypt
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for (i = 0; i < M.size(); ++i) M[i] = M[i] ^ sc.gen();
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//append the message part to the key block.
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bvector Mb;
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Mb.from_bytes (M);
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cipher.append (Mb);
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return 0;
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}
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template < class privkey_type,
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int plainsize,
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int ciphersize,
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int errorcount,
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class hash_type,
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class pad_hash_type,
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class scipher,
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int ranksize >
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static int fo_decrypt (const bvector&cipher, bvector&plain,
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sencode* privkey)
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{
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uint i;
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//load the key
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privkey_type Priv;
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if (!Priv.unserialize (privkey)) return 1;
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if (Priv.prepare()) return 100;
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//verify that key parameters match the scheme
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if (Priv.plain_size() != plainsize) return 2;
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if (Priv.cipher_size() != ciphersize) return 3;
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if (Priv.error_count() != errorcount) return 4;
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//get the McE part
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if (cipher.size() < ciphersize) return 5;
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bvector mce_cipher, mce_plain, ev;
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cipher.get_block (0, ciphersize, mce_cipher);
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//get and check the message size for later
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uint msize = cipher.size() - ciphersize;
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if (msize & 0x7) return 6;
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/*
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* There is an (easy) timing attack on McEliece variants' decryption
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* that determines whether McEliece decoding failed or CCA2 padding
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* verification failed and can be (pretty easily) used to recover all
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* errors in the error vector. To make it a (whole lot) harder, we make
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* sure that following computation runs the same in both cases, at
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* least to practical extent.
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*
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* Note that this doesn't cover potential attack on underlying
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* rootfinding algorithm (but that one is way harder to run correctly).
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*
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* bool failed is volatile because we need to force the compiler not to
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* optimize out the loop that constructs the dummy error vector.
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*/
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//decrypt the symmetric key
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volatile bool failed = Priv.decrypt (mce_cipher, mce_plain, ev);
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if (failed) { //prevent memory errors
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ev.resize (ciphersize, 0);
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mce_plain.resize (plainsize, 0);
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}
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/*
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* if decoding failed, ev contains something weird. We need to make it
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* to contain some dummy (but still valid) error vector that would work
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* with CCA2 verification and fail later.
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*
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* ev now contains the broken error vector; let's fix it up to
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*
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* 11111(errorcount of 1s)111100000000000
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*/
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for (i = 0; i < ev.size(); ++i)
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ev[i] = failed ? (i < errorcount) : ev[i];
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//convert stuff to byte vectors
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std::vector<byte> K, M;
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mce_plain.to_bytes (K);
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bvector Mb;
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cipher.get_block (ciphersize, msize, Mb);
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Mb.to_bytes (M);
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//prepare symmetric cipher
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scipher sc;
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sc.init ();
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//stuff in the whole key
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sc.load_key_vector (K);
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//decrypt the message part
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for (i = 0; i < M.size(); ++i) M[i] = M[i] ^ sc.gen();
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//compute the hash of K+M
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std::vector<byte>H, M2;
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M2 = M;
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M2.insert (M2.end(), K.begin(), K.end());
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hash_type hf;
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H = hf (M2);
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//colex rank the vector to hash (it is faster than unranking)
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bvector ev_rank;
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ev.colex_rank (ev_rank);
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ev_rank.resize (ranksize, 0);
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for (i = 0; i < ranksize; ++i) //cyclic hash repetition again
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if (ev_rank[i] != (1 & (H[ (i >> 3) % H.size()]
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>> (i & 0x7))))
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return 7;
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//if the message seems okay, unpad and return it.
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pad_hash_type phf;
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if (!message_unpad (M, plain, phf)) return 8;
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return 0;
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}
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/*
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* Instances for MCE-QCMDPC algorithms
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*/
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#define mceqcmdpc_create_keypair_func(name,bs,bc,wi,t,rnd,delta) \
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int algo_mceqcmdpc##name::create_keypair (sencode**pub, sencode**priv, prng&rng) \
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{ \
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return mceqcmdpc_create_keypair<bs,bc,wi,t,rnd,delta> (pub, priv, rng); \
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}
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#if HAVE_CRYPTOPP==1
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mceqcmdpc_create_keypair_func (128, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256, 32771, 2, 137, 264, 40, 4)
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mceqcmdpc_create_keypair_func (128cha, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256cha, 32771, 2, 137, 264, 40, 4)
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mceqcmdpc_create_keypair_func (128xs, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256xs, 32771, 2, 137, 264, 40, 4)
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#endif //HAVE_CRYPTOPP==1
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mceqcmdpc_create_keypair_func (128cube, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256cube, 32771, 2, 137, 264, 40, 4)
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mceqcmdpc_create_keypair_func (128cubecha, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256cubecha, 32771, 2, 137, 264, 40, 4)
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mceqcmdpc_create_keypair_func (128cubexs, 9857, 2, 71, 134, 25, 4)
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mceqcmdpc_create_keypair_func (256cubexs, 32771, 2, 137, 264, 40, 4)
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#define mceqcmdpc_create_encdec_func(name,bs,bc,errcount,hash_type,pad_hash_type,scipher,ranksize) \
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int algo_mceqcmdpc##name::encrypt (const bvector&plain, bvector&cipher, \
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sencode* pubkey, prng&rng) \
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{ \
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return fo_encrypt \
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< mce_qcmdpc::pubkey, \
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bs*(bc-1), bs*bc, errcount, \
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hash_type, \
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pad_hash_type, \
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scipher, \
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ranksize > \
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(plain, cipher, pubkey, rng); \
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} \
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int algo_mceqcmdpc##name::decrypt (const bvector&cipher, bvector&plain, \
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sencode* privkey) \
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{ \
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return fo_decrypt \
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< mce_qcmdpc::privkey, \
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bs*(bc-1), bs*bc, errcount, \
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hash_type, \
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pad_hash_type, \
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scipher, \
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ranksize > \
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(cipher, plain, privkey); \
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}
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#if HAVE_CRYPTOPP==1
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mceqcmdpc_create_encdec_func (128, 9857, 2, 134, sha256hash, rmd128hash, arcfour_fo_cipher, 1152)
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mceqcmdpc_create_encdec_func (256, 32771, 2, 264, sha512hash, sha256hash, arcfour_fo_cipher, 2475)
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mceqcmdpc_create_encdec_func (128cha, 9857, 2, 134, sha256hash, rmd128hash, chacha20, 1152)
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mceqcmdpc_create_encdec_func (256cha, 32771, 2, 264, sha512hash, sha256hash, chacha20, 2475)
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mceqcmdpc_create_encdec_func (128xs, 9857, 2, 134, sha256hash, rmd128hash, xsynd, 1152)
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mceqcmdpc_create_encdec_func (256xs, 32771, 2, 264, sha512hash, sha256hash, xsynd, 2475)
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#endif //HAVE_CRYPTOPP==1
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mceqcmdpc_create_encdec_func (128cube, 9857, 2, 134, cube256hash, cube128hash, arcfour_fo_cipher, 1152)
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mceqcmdpc_create_encdec_func (256cube, 32771, 2, 264, cube512hash, cube256hash, arcfour_fo_cipher, 2475)
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mceqcmdpc_create_encdec_func (128cubecha, 9857, 2, 134, cube256hash, cube128hash, chacha20, 1152)
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mceqcmdpc_create_encdec_func (256cubecha, 32771, 2, 264, cube512hash, cube256hash, chacha20, 2475)
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mceqcmdpc_create_encdec_func (128cubexs, 9857, 2, 134, cube256hash, cube128hash, xsynd, 1152)
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mceqcmdpc_create_encdec_func (256cubexs, 32771, 2, 264, cube512hash, cube256hash, xsynd, 2475)
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