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425 lines
14 KiB
C++
425 lines
14 KiB
C++
// Copyright (c) 2016, Monero Research Labs
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//
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// Author: Shen Noether <shen.noether@gmx.com>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "misc_log_ex.h"
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#include "rctOps.h"
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using namespace crypto;
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using namespace std;
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namespace rct {
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//Various key initialization functions
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//initializes a key matrix;
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//first parameter is rows,
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//second is columns
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keyM keyMInit(size_t rows, size_t cols) {
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keyM rv(cols);
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size_t i = 0;
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for (i = 0 ; i < cols ; i++) {
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rv[i] = keyV(rows);
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}
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return rv;
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}
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//Various key generation functions
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//generates a random scalar which can be used as a secret key or mask
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void skGen(key &sk) {
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sk = crypto::rand<key>();
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sc_reduce32(sk.bytes);
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}
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//generates a random scalar which can be used as a secret key or mask
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key skGen() {
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key sk = crypto::rand<key>();
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sc_reduce32(sk.bytes);
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return sk;
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}
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//Generates a vector of secret key
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//Mainly used in testing
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keyV skvGen(size_t rows ) {
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keyV rv(rows);
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size_t i = 0;
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crypto::rand(rows * sizeof(key), (uint8_t*)&rv[0]);
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for (i = 0 ; i < rows ; i++) {
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sc_reduce32(rv[i].bytes);
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}
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return rv;
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}
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//generates a random curve point (for testing)
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key pkGen() {
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key sk = skGen();
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key pk = scalarmultBase(sk);
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return pk;
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}
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//generates a random secret and corresponding public key
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void skpkGen(key &sk, key &pk) {
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skGen(sk);
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scalarmultBase(pk, sk);
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}
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//generates a random secret and corresponding public key
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tuple<key, key> skpkGen() {
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key sk = skGen();
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key pk = scalarmultBase(sk);
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return make_tuple(sk, pk);
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}
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//generates C =aG + bH from b, a is given..
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void genC(key & C, const key & a, xmr_amount amount) {
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key bH = scalarmultH(d2h(amount));
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addKeys1(C, a, bH);
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}
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//generates a <secret , public> / Pedersen commitment to the amount
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tuple<ctkey, ctkey> ctskpkGen(xmr_amount amount) {
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ctkey sk, pk;
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skpkGen(sk.dest, pk.dest);
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skpkGen(sk.mask, pk.mask);
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key am = d2h(amount);
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key bH = scalarmultH(am);
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addKeys(pk.mask, pk.mask, bH);
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return make_tuple(sk, pk);
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}
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//generates a <secret , public> / Pedersen commitment but takes bH as input
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tuple<ctkey, ctkey> ctskpkGen(const key &bH) {
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ctkey sk, pk;
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skpkGen(sk.dest, pk.dest);
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skpkGen(sk.mask, pk.mask);
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addKeys(pk.mask, pk.mask, bH);
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return make_tuple(sk, pk);
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}
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key zeroCommit(xmr_amount amount) {
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key mask = identity();
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mask = scalarmultBase(mask);
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key am = d2h(amount);
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key bH = scalarmultH(am);
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addKeys(mask, mask, bH);
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return mask;
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}
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key commit(xmr_amount amount, const key &mask) {
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key c = scalarmultBase(mask);
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key am = d2h(amount);
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key bH = scalarmultH(am);
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addKeys(c, c, bH);
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return c;
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}
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//generates a random uint long long (for testing)
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xmr_amount randXmrAmount(xmr_amount upperlimit) {
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return h2d(skGen()) % (upperlimit);
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}
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//Scalar multiplications of curve points
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//does a * G where a is a scalar and G is the curve basepoint
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void scalarmultBase(key &aG,const key &a) {
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ge_p3 point;
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sc_reduce32copy(aG.bytes, a.bytes); //do this beforehand!
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ge_scalarmult_base(&point, aG.bytes);
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ge_p3_tobytes(aG.bytes, &point);
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}
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//does a * G where a is a scalar and G is the curve basepoint
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key scalarmultBase(const key & a) {
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ge_p3 point;
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key aG;
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sc_reduce32copy(aG.bytes, a.bytes); //do this beforehand
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ge_scalarmult_base(&point, aG.bytes);
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ge_p3_tobytes(aG.bytes, &point);
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return aG;
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}
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//does a * P where a is a scalar and P is an arbitrary point
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void scalarmultKey(key & aP, const key &P, const key &a) {
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ge_p3 A;
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ge_p2 R;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A, P.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_scalarmult(&R, a.bytes, &A);
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ge_tobytes(aP.bytes, &R);
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}
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//does a * P where a is a scalar and P is an arbitrary point
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key scalarmultKey(const key & P, const key & a) {
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ge_p3 A;
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ge_p2 R;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A, P.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_scalarmult(&R, a.bytes, &A);
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key aP;
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ge_tobytes(aP.bytes, &R);
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return aP;
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}
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//Computes aH where H= toPoint(cn_fast_hash(G)), G the basepoint
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key scalarmultH(const key & a) {
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ge_p3 A;
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ge_p2 R;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A, H.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_scalarmult(&R, a.bytes, &A);
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key aP;
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ge_tobytes(aP.bytes, &R);
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return aP;
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}
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//Curve addition / subtractions
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//for curve points: AB = A + B
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void addKeys(key &AB, const key &A, const key &B) {
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ge_p3 B2, A2;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&B2, B.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A2, A.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_cached tmp2;
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ge_p3_to_cached(&tmp2, &B2);
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ge_p1p1 tmp3;
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ge_add(&tmp3, &A2, &tmp2);
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ge_p1p1_to_p3(&A2, &tmp3);
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ge_p3_tobytes(AB.bytes, &A2);
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}
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//addKeys1
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//aGB = aG + B where a is a scalar, G is the basepoint, and B is a point
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void addKeys1(key &aGB, const key &a, const key & B) {
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key aG = scalarmultBase(a);
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addKeys(aGB, aG, B);
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}
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//addKeys2
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//aGbB = aG + bB where a, b are scalars, G is the basepoint and B is a point
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void addKeys2(key &aGbB, const key &a, const key &b, const key & B) {
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ge_p2 rv;
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ge_p3 B2;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&B2, B.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_double_scalarmult_base_vartime(&rv, b.bytes, &B2, a.bytes);
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ge_tobytes(aGbB.bytes, &rv);
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}
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//Does some precomputation to make addKeys3 more efficient
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// input B a curve point and output a ge_dsmp which has precomputation applied
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void precomp(ge_dsmp rv, const key & B) {
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ge_p3 B2;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&B2, B.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_dsm_precomp(rv, &B2);
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}
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//addKeys3
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//aAbB = a*A + b*B where a, b are scalars, A, B are curve points
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//B must be input after applying "precomp"
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void addKeys3(key &aAbB, const key &a, const key &A, const key &b, const ge_dsmp B) {
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ge_p2 rv;
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ge_p3 A2;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A2, A.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_double_scalarmult_precomp_vartime(&rv, a.bytes, &A2, b.bytes, B);
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ge_tobytes(aAbB.bytes, &rv);
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}
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//subtract Keys (subtracts curve points)
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//AB = A - B where A, B are curve points
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void subKeys(key & AB, const key &A, const key &B) {
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ge_p3 B2, A2;
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&B2, B.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&A2, A.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_cached tmp2;
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ge_p3_to_cached(&tmp2, &B2);
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ge_p1p1 tmp3;
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ge_sub(&tmp3, &A2, &tmp2);
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ge_p1p1_to_p3(&A2, &tmp3);
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ge_p3_tobytes(AB.bytes, &A2);
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}
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//checks if A, B are equal as curve points
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//without doing curve operations
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bool equalKeys(const key & a, const key & b) {
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bool rv = true;
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for (int i = 0; i < 32; ++i) {
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if (a.bytes[i] != b.bytes[i]) {
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rv = false;
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}
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}
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return rv;
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}
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//Hashing - cn_fast_hash
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//be careful these are also in crypto namespace
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//cn_fast_hash for arbitrary multiples of 32 bytes
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void cn_fast_hash(key &hash, const void * data, const std::size_t l) {
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keccak((const uint8_t *)data, l, hash.bytes, 32);
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}
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void hash_to_scalar(key &hash, const void * data, const std::size_t l) {
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cn_fast_hash(hash, data, l);
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sc_reduce32(hash.bytes);
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}
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//cn_fast_hash for a 32 byte key
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void cn_fast_hash(key & hash, const key & in) {
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keccak((const uint8_t *)in.bytes, 32, hash.bytes, 32);
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}
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void hash_to_scalar(key & hash, const key & in) {
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cn_fast_hash(hash, in);
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sc_reduce32(hash.bytes);
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}
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//cn_fast_hash for a 32 byte key
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key cn_fast_hash(const key & in) {
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key hash;
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keccak((const uint8_t *)in.bytes, 32, hash.bytes, 32);
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return hash;
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}
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key hash_to_scalar(const key & in) {
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key hash = cn_fast_hash(in);
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sc_reduce32(hash.bytes);
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return hash;
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}
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//cn_fast_hash for a 128 byte unsigned char
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key cn_fast_hash128(const void * in) {
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key hash;
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keccak((const uint8_t *)in, 128, hash.bytes, 32);
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return hash;
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}
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key hash_to_scalar128(const void * in) {
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key hash = cn_fast_hash128(in);
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sc_reduce32(hash.bytes);
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return hash;
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}
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//cn_fast_hash for multisig purpose
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//This takes the outputs and commitments
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//and hashes them into a 32 byte sized key
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key cn_fast_hash(const ctkeyV &PC) {
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key rv;
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cn_fast_hash(rv, &PC[0], 64*PC.size());
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return rv;
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}
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key hash_to_scalar(const ctkeyV &PC) {
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key rv = cn_fast_hash(PC);
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sc_reduce32(rv.bytes);
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return rv;
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}
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//cn_fast_hash for a key-vector of arbitrary length
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//this is useful since you take a number of keys
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//put them in the key vector and it concatenates them
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//and then hashes them
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key cn_fast_hash(const keyV &keys) {
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key rv;
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cn_fast_hash(rv, &keys[0], keys.size() * sizeof(keys[0]));
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//dp(rv);
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return rv;
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}
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key hash_to_scalar(const keyV &keys) {
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key rv = cn_fast_hash(keys);
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sc_reduce32(rv.bytes);
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return rv;
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}
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key hashToPointSimple(const key & hh) {
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key pointk;
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ge_p1p1 point2;
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ge_p2 point;
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ge_p3 res;
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key h = cn_fast_hash(hh);
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CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&res, h.bytes) == 0, "ge_frombytes_vartime failed at "+boost::lexical_cast<std::string>(__LINE__));
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ge_p3_to_p2(&point, &res);
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ge_mul8(&point2, &point);
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ge_p1p1_to_p3(&res, &point2);
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ge_p3_tobytes(pointk.bytes, &res);
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return pointk;
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}
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key hashToPoint(const key & hh) {
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key pointk;
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ge_p2 point;
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ge_p1p1 point2;
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ge_p3 res;
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key h = cn_fast_hash(hh);
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ge_fromfe_frombytes_vartime(&point, h.bytes);
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ge_mul8(&point2, &point);
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ge_p1p1_to_p3(&res, &point2);
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ge_p3_tobytes(pointk.bytes, &res);
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return pointk;
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}
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void hashToPoint(key & pointk, const key & hh) {
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ge_p2 point;
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ge_p1p1 point2;
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ge_p3 res;
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key h = cn_fast_hash(hh);
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ge_fromfe_frombytes_vartime(&point, h.bytes);
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ge_mul8(&point2, &point);
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ge_p1p1_to_p3(&res, &point2);
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ge_p3_tobytes(pointk.bytes, &res);
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}
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//sums a vector of curve points (for scalars use sc_add)
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void sumKeys(key & Csum, const keyV & Cis) {
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identity(Csum);
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size_t i = 0;
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for (i = 0; i < Cis.size(); i++) {
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addKeys(Csum, Csum, Cis[i]);
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}
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}
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//Elliptic Curve Diffie Helman: encodes and decodes the amount b and mask a
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// where C= aG + bH
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void ecdhEncode(ecdhTuple & unmasked, const key & sharedSec) {
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key sharedSec1 = hash_to_scalar(sharedSec);
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key sharedSec2 = hash_to_scalar(sharedSec1);
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//encode
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sc_add(unmasked.mask.bytes, unmasked.mask.bytes, sharedSec1.bytes);
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sc_add(unmasked.amount.bytes, unmasked.amount.bytes, sharedSec2.bytes);
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}
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void ecdhDecode(ecdhTuple & masked, const key & sharedSec) {
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key sharedSec1 = hash_to_scalar(sharedSec);
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key sharedSec2 = hash_to_scalar(sharedSec1);
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//decode
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sc_sub(masked.mask.bytes, masked.mask.bytes, sharedSec1.bytes);
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sc_sub(masked.amount.bytes, masked.amount.bytes, sharedSec2.bytes);
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}
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}
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