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hw_crypto.c
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// Copyright 2018 The Beam Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <assert.h>
#include "multimac.h"
#include "oracle.h"
#include "noncegen.h"
#include "coinid.h"
#include "kdf.h"
#include "rangeproof.h"
#include "sign.h"
#include "keykeeper.h"
#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wunused-function"
#else
# pragma warning (push, 0) // suppress warnings from secp256k1
# pragma warning (disable: 4706 4701) // assignment within conditional expression
#endif
#include "secp256k1-zkp/src/group_impl.h"
#include "secp256k1-zkp/src/scalar_impl.h"
#include "secp256k1-zkp/src/field_impl.h"
#include "secp256k1-zkp/src/hash_impl.h"
#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
# pragma GCC diagnostic pop
#else
# pragma warning (default: 4706 4701)
# pragma warning (pop)
#endif
#define SECURE_ERASE_OBJ(x) memset(&x, 0, sizeof(x))
#define s_WNaf_HiBit 0x80
static_assert(BeamCrypto_MultiMac_Fast_nCount < s_WNaf_HiBit, "");
#ifdef USE_SCALAR_4X64
typedef uint64_t secp256k1_scalar_uint;
#else // USE_SCALAR_4X64
typedef uint32_t secp256k1_scalar_uint;
#endif // USE_SCALAR_4X64
#ifndef _countof
# define _countof(arr) sizeof(arr) / sizeof((arr)[0])
#endif
#define secp256k1_scalar_WordBits (sizeof(secp256k1_scalar_uint) * 8)
//////////////////////////////
// MultiMac
typedef struct
{
int m_Word;
secp256k1_scalar_uint m_Msk;
} BitWalker;
inline static void BitWalker_SetPos(BitWalker* p, uint8_t iBit)
{
p->m_Word = iBit / secp256k1_scalar_WordBits;
p->m_Msk = ((secp256k1_scalar_uint) 1) << (iBit & (secp256k1_scalar_WordBits - 1));
}
inline static void BitWalker_MoveUp(BitWalker* p)
{
if (!(p->m_Msk <<= 1))
{
p->m_Msk = 1;
p->m_Word++;
}
}
inline static void BitWalker_MoveDown(BitWalker* p)
{
if (!(p->m_Msk >>= 1))
{
p->m_Msk = ((secp256k1_scalar_uint) 1) << (secp256k1_scalar_WordBits - 1);
p->m_Word--;
}
}
inline static secp256k1_scalar_uint BitWalker_get(const BitWalker* p, const secp256k1_scalar* pK)
{
return pK->d[p->m_Word] & p->m_Msk;
}
inline static void BitWalker_xor(const BitWalker* p, secp256k1_scalar* pK)
{
pK->d[p->m_Word] ^= p->m_Msk;
}
static void WNaf_Cursor_MoveNext(BeamCrypto_MultiMac_WNaf_Cursor* p, const secp256k1_scalar* pK)
{
BitWalker bw;
BitWalker_SetPos(&bw, --p->m_iBit);
// find next nnz bit
for (; ; p->m_iBit--, BitWalker_MoveDown(&bw))
{
if (BitWalker_get(&bw, pK))
break;
if (!p->m_iBit)
{
// end
p->m_iBit = 1;
p->m_iElement = s_WNaf_HiBit;
return;
}
}
uint8_t nOdd = 1;
uint8_t nWndBits = BeamCrypto_MultiMac_Fast_nBits - 1;
if (nWndBits > p->m_iBit)
nWndBits = p->m_iBit;
for (uint8_t i = 0; i < nWndBits; i++, p->m_iBit--)
{
BitWalker_MoveDown(&bw);
nOdd = (nOdd << 1) | (BitWalker_get(&bw, pK) != 0);
}
for (; !(1 & nOdd); p->m_iBit++)
nOdd >>= 1;
p->m_iElement = nOdd >> 1;
}
static int Scalar_SplitPosNeg(BeamCrypto_MultiMac_Scalar* p)
{
#if BeamCrypto_MultiMac_Directions != 2
static_assert(BeamCrypto_MultiMac_Directions == 1, "");
#else // BeamCrypto_MultiMac_Directions
memset(p->m_pK[1].d, 0, sizeof(p->m_pK[1].d));
uint8_t iBit = 0;
BitWalker bw;
bw.m_Word = 0;
bw.m_Msk = 1;
while (1)
{
// find nnz bit
while (1)
{
if (iBit >= BeamCrypto_nBits - BeamCrypto_MultiMac_Fast_nBits)
return 0;
if (BitWalker_get(&bw, p->m_pK))
break;
iBit++;
BitWalker_MoveUp(&bw);
}
BitWalker bw0 = bw;
iBit += BeamCrypto_MultiMac_Fast_nBits;
for (uint32_t i = 0; i < BeamCrypto_MultiMac_Fast_nBits; i++)
BitWalker_MoveUp(&bw); // akward
if (!BitWalker_get(&bw, p->m_pK))
continue; // interleaving is not needed
// set negative bits
BitWalker_xor(&bw0, p->m_pK);
BitWalker_xor(&bw0, p->m_pK + 1);
for (uint8_t i = 1; i < BeamCrypto_MultiMac_Fast_nBits; i++)
{
BitWalker_MoveUp(&bw0);
secp256k1_scalar_uint val = BitWalker_get(&bw0, p->m_pK);
BitWalker_xor(&bw0, p->m_pK + !val);
}
// propagate carry
while (1)
{
BitWalker_xor(&bw, p->m_pK);
if (BitWalker_get(&bw, p->m_pK))
break;
if (! ++iBit)
return 1; // carry goes outside
BitWalker_MoveUp(&bw);
}
}
#endif // BeamCrypto_MultiMac_Directions
return 0;
}
void mem_cmov(unsigned int* pDst, const unsigned int* pSrc, int flag, unsigned int nWords)
{
const unsigned int mask0 = flag + ~((unsigned int) 0);
const unsigned int mask1 = ~mask0;
for (unsigned int n = 0; n < nWords; n++)
pDst[n] = (pDst[n] & mask0) | (pSrc[n] & mask1);
}
void BeamCrypto_MultiMac_Calculate(const BeamCrypto_MultiMac_Context* p)
{
secp256k1_gej_set_infinity(p->m_pRes);
for (unsigned int i = 0; i < p->m_Fast; i++)
{
BeamCrypto_MultiMac_WNaf* pWnaf = p->m_pWnaf + i;
BeamCrypto_MultiMac_Scalar* pS = p->m_pS + i;
pWnaf->m_pC[0].m_iBit = 0;
int carry = Scalar_SplitPosNeg(pS);
if (carry)
pWnaf->m_pC[0].m_iElement = s_WNaf_HiBit;
else
WNaf_Cursor_MoveNext(pWnaf->m_pC, pS->m_pK);
#if BeamCrypto_MultiMac_Directions == 2
pWnaf->m_pC[1].m_iBit = 0;
WNaf_Cursor_MoveNext(pWnaf->m_pC + 1, pS->m_pK + 1);
#endif // BeamCrypto_MultiMac_Directions
}
secp256k1_ge ge;
secp256k1_ge_storage ges;
for (uint16_t iBit = BeamCrypto_nBits + 1; iBit--; ) // extra bit may be necessary because of interleaving
{
secp256k1_gej_double_var(p->m_pRes, p->m_pRes, 0); // would be fast if zero, no need to check explicitly
if (!(iBit % BeamCrypto_MultiMac_Secure_nBits) && (iBit < BeamCrypto_nBits) && p->m_Secure)
{
static_assert(!(secp256k1_scalar_WordBits % BeamCrypto_MultiMac_Secure_nBits), "");
unsigned int iWord = iBit / secp256k1_scalar_WordBits;
unsigned int nShift = iBit % secp256k1_scalar_WordBits;
const secp256k1_scalar_uint nMsk = ((1U << BeamCrypto_MultiMac_Secure_nBits) - 1);
for (unsigned int i = 0; i < p->m_Secure; i++)
{
unsigned int iElement = (p->m_pSecureK[i].d[iWord] >> nShift) & nMsk;
const BeamCrypto_MultiMac_Secure* pGen = p->m_pGenSecure + i;
for (unsigned int j = 0; j < BeamCrypto_MultiMac_Secure_nCount; j++)
{
static_assert(sizeof(ges) == sizeof(pGen->m_pPt[j]), "");
static_assert(!(sizeof(ges) % sizeof(unsigned int)), "");
mem_cmov(
(unsigned int*) &ges,
(unsigned int*) (pGen->m_pPt + j),
iElement == j,
sizeof(ges) / sizeof(unsigned int));
}
secp256k1_ge_from_storage(&ge, &ges);
if (p->m_pZDenom)
secp256k1_gej_add_zinv_var(p->m_pRes, p->m_pRes, &ge, p->m_pZDenom);
else
secp256k1_gej_add_ge_var(p->m_pRes, p->m_pRes, &ge, 0);
}
}
for (unsigned int i = 0; i < p->m_Fast; i++)
{
BeamCrypto_MultiMac_WNaf* pWnaf = p->m_pWnaf + i;
for (unsigned int j = 0; j < BeamCrypto_MultiMac_Directions; j++)
{
BeamCrypto_MultiMac_WNaf_Cursor* pWc = pWnaf->m_pC + j;
if (((uint8_t) iBit) != pWc->m_iBit)
continue;
// special case: resolve 256-0 ambiguity
if ((pWc->m_iElement ^ ((uint8_t) (iBit >> 1))) & s_WNaf_HiBit)
continue;
secp256k1_ge_from_storage(&ge, p->m_pGenFast[i].m_pPt + (pWc->m_iElement & ~s_WNaf_HiBit));
if (j)
secp256k1_ge_neg(&ge, &ge);
secp256k1_gej_add_ge_var(p->m_pRes, p->m_pRes, &ge, 0);
if (iBit)
WNaf_Cursor_MoveNext(pWc, p->m_pS[i].m_pK + j);
}
}
}
SECURE_ERASE_OBJ(ges);
if (p->m_pZDenom)
// fix denominator
secp256k1_fe_mul(&p->m_pRes->z, &p->m_pRes->z, p->m_pZDenom);
for (unsigned int i = 0; i < p->m_Secure; i++)
{
secp256k1_ge_from_storage(&ge, p->m_pGenSecure[i].m_pPt + BeamCrypto_MultiMac_Secure_nCount);
secp256k1_gej_add_ge_var(p->m_pRes, p->m_pRes, &ge, 0);
}
}
//////////////////////////////
// Batch normalization
static void secp256k1_gej_rescale_XY(secp256k1_gej* pGej, const secp256k1_fe* pZ)
{
// equivalent of secp256k1_gej_rescale, but doesn't change z coordinate
// A bit more effective when the value of z is known in advance (such as when normalizing)
secp256k1_fe zz;
secp256k1_fe_sqr(&zz, pZ);
secp256k1_fe_mul(&pGej->x, &pGej->x, &zz);
secp256k1_fe_mul(&pGej->y, &pGej->y, &zz);
secp256k1_fe_mul(&pGej->y, &pGej->y, pZ);
}
static void BatchNormalize_Fwd(secp256k1_fe* pFe, unsigned int n, const secp256k1_gej* pGej, const secp256k1_fe* pFePrev)
{
if (n)
secp256k1_fe_mul(pFe, pFePrev, &pGej->z);
else
*pFe = pGej[0].z;
}
static void BatchNormalize_Apex(secp256k1_fe* pZDenom, secp256k1_fe* pFePrev, int nNormalize)
{
if (nNormalize)
secp256k1_fe_inv(pZDenom, pFePrev); // the only expensive call
else
secp256k1_fe_set_int(pZDenom, 1);
}
static void BatchNormalize_Bwd(secp256k1_fe* pFe, unsigned int n, secp256k1_gej* pGej, const secp256k1_fe* pFePrev, secp256k1_fe* pZDenom)
{
if (n)
secp256k1_fe_mul(pFe, pFePrev, pZDenom);
else
*pFe = *pZDenom;
secp256k1_gej_rescale_XY(pGej, pFe);
secp256k1_fe_mul(pZDenom, pZDenom, &pGej->z);
}
static void BeamCrypto_ToCommonDenominator(unsigned int nCount, secp256k1_gej* pGej, secp256k1_fe* pFe, secp256k1_fe* pZDenom, int nNormalize)
{
assert(nCount);
for (unsigned int i = 0; i < nCount; i++)
BatchNormalize_Fwd(pFe + i, i, pGej + i, pFe + i - 1);
BatchNormalize_Apex(pZDenom, pFe + nCount - 1, nNormalize);
for (unsigned int i = nCount; i--; )
BatchNormalize_Bwd(pFe + i, i, pGej + i, pFe + i - 1, pZDenom);
}
static void secp256k1_ge_set_gej_normalized(secp256k1_ge* pGe, const secp256k1_gej* pGej)
{
pGe->infinity = pGej->infinity;
pGe->x = pGej->x;
pGe->y = pGej->y;
}
static void BeamCrypto_MultiMac_SetCustom_Nnz(BeamCrypto_MultiMac_Context* p, BeamCrypto_FlexPoint* pFlex)
{
assert(p->m_Fast == 1);
assert(p->m_pZDenom);
BeamCrypto_FlexPoint_MakeGej(pFlex);
assert(BeamCrypto_FlexPoint_Gej & pFlex->m_Flags);
assert(!secp256k1_gej_is_infinity(&pFlex->m_Gej));
secp256k1_gej pOdds[BeamCrypto_MultiMac_Fast_nCount];
pOdds[0] = pFlex->m_Gej;
// calculate odd powers
secp256k1_gej x2;
secp256k1_gej_double_var(&x2, pOdds, 0);
for (unsigned int i = 1; i < BeamCrypto_MultiMac_Fast_nCount; i++)
{
secp256k1_gej_add_var(pOdds + i, pOdds + i - 1, &x2, 0);
assert(!secp256k1_gej_is_infinity(pOdds + i)); // odd powers of non-zero point must not be zero!
}
secp256k1_fe pFe[BeamCrypto_MultiMac_Fast_nCount];
BeamCrypto_ToCommonDenominator(BeamCrypto_MultiMac_Fast_nCount, pOdds, pFe, p->m_pZDenom, 0);
for (unsigned int i = 0; i < BeamCrypto_MultiMac_Fast_nCount; i++)
{
secp256k1_ge ge;
secp256k1_ge_set_gej_normalized(&ge, pOdds + i);
secp256k1_ge_to_storage((secp256k1_ge_storage*)p->m_pGenFast[0].m_pPt + i, &ge);
}
}
//////////////////////////////
// NonceGenerator
void BeamCrypto_NonceGenerator_InitBegin(BeamCrypto_NonceGenerator* p, secp256k1_hmac_sha256_t* pHMac, const char* szSalt, size_t nSalt)
{
p->m_Counter = 0;
p->m_FirstTime = 1;
p->m_pContext = 0;
p->m_nContext = 0;
secp256k1_hmac_sha256_initialize(pHMac, (uint8_t*) szSalt, nSalt);
}
void BeamCrypto_NonceGenerator_InitEnd(BeamCrypto_NonceGenerator* p, secp256k1_hmac_sha256_t* pHMac)
{
secp256k1_hmac_sha256_finalize(pHMac, p->m_Prk.m_pVal);
}
void BeamCrypto_NonceGenerator_Init(BeamCrypto_NonceGenerator* p, const char* szSalt, size_t nSalt, const BeamCrypto_UintBig* pSeed)
{
secp256k1_hmac_sha256_t hmac;
BeamCrypto_NonceGenerator_InitBegin(p, &hmac, szSalt, nSalt);
secp256k1_hmac_sha256_write(&hmac, pSeed->m_pVal, sizeof(pSeed->m_pVal));
BeamCrypto_NonceGenerator_InitEnd(p, &hmac);
}
void BeamCrypto_NonceGenerator_NextOkm(BeamCrypto_NonceGenerator* p)
{
// Expand
secp256k1_hmac_sha256_t hmac;
secp256k1_hmac_sha256_initialize(&hmac, p->m_Prk.m_pVal, sizeof(p->m_Prk.m_pVal));
if (p->m_FirstTime)
p->m_FirstTime = 0;
else
secp256k1_hmac_sha256_write(&hmac, p->m_Okm.m_pVal, sizeof(p->m_Okm.m_pVal));
secp256k1_hmac_sha256_write(&hmac, p->m_pContext, p->m_nContext);
p->m_Counter++;
secp256k1_hmac_sha256_write(&hmac, &p->m_Counter, sizeof(p->m_Counter));
secp256k1_hmac_sha256_finalize(&hmac, p->m_Okm.m_pVal);
}
static int ScalarImportNnz(secp256k1_scalar* pS, const uint8_t* p)
{
int overflow;
secp256k1_scalar_set_b32(pS, p, &overflow);
return !(overflow || secp256k1_scalar_is_zero(pS));
}
void BeamCrypto_NonceGenerator_NextScalar(BeamCrypto_NonceGenerator* p, secp256k1_scalar* pS)
{
while (1)
{
BeamCrypto_NonceGenerator_NextOkm(p);
if (ScalarImportNnz(pS, p->m_Okm.m_pVal))
break;
}
}
static int IsUintBigZero(const BeamCrypto_UintBig* p)
{
// const-time isn't required
for (unsigned int i = 0; i < _countof(p->m_pVal); i++)
if (p->m_pVal[i])
return 0;
return 1;
}
//////////////////////////////
// Point
void BeamCrypto_FlexPoint_MakeCompact(BeamCrypto_FlexPoint* pFlex)
{
if ((BeamCrypto_FlexPoint_Compact & pFlex->m_Flags) || !pFlex->m_Flags)
return;
BeamCrypto_FlexPoint_MakeGe(pFlex);
assert(BeamCrypto_FlexPoint_Ge & pFlex->m_Flags);
if (secp256k1_ge_is_infinity(&pFlex->m_Ge))
memset(&pFlex->m_Compact, 0, sizeof(pFlex->m_Compact));
else
{
secp256k1_fe_normalize(&pFlex->m_Ge.x);
secp256k1_fe_normalize(&pFlex->m_Ge.y);
secp256k1_fe_get_b32(pFlex->m_Compact.m_X.m_pVal, &pFlex->m_Ge.x);
pFlex->m_Compact.m_Y = (secp256k1_fe_is_odd(&pFlex->m_Ge.y) != 0);
}
pFlex->m_Flags |= BeamCrypto_FlexPoint_Compact;
}
void BeamCrypto_FlexPoint_MakeGej(BeamCrypto_FlexPoint* pFlex)
{
if (BeamCrypto_FlexPoint_Gej & pFlex->m_Flags)
return;
BeamCrypto_FlexPoint_MakeGe(pFlex);
if (!pFlex->m_Flags)
return;
assert(BeamCrypto_FlexPoint_Ge & pFlex->m_Flags);
secp256k1_gej_set_ge(&pFlex->m_Gej, &pFlex->m_Ge);
pFlex->m_Flags |= BeamCrypto_FlexPoint_Gej;
}
void BeamCrypto_FlexPoint_MakeGe(BeamCrypto_FlexPoint* pFlex)
{
if (BeamCrypto_FlexPoint_Ge & pFlex->m_Flags)
return;
if (BeamCrypto_FlexPoint_Gej & pFlex->m_Flags)
secp256k1_ge_set_gej_var(&pFlex->m_Ge, &pFlex->m_Gej); // expensive, better to a batch convertion
else
{
if (!(BeamCrypto_FlexPoint_Compact & pFlex->m_Flags))
return;
pFlex->m_Flags = 0; // will restore Compact flag iff import is successful
if (pFlex->m_Compact.m_Y > 1)
return; // not well-formed
secp256k1_fe nx;
if (!secp256k1_fe_set_b32(&nx, pFlex->m_Compact.m_X.m_pVal))
return; // not well-formed
if (!secp256k1_ge_set_xo_var(&pFlex->m_Ge, &nx, pFlex->m_Compact.m_Y))
{
// be convention zeroed Compact is a zero point
if (pFlex->m_Compact.m_Y || !IsUintBigZero(&pFlex->m_Compact.m_X))
return;
pFlex->m_Ge.infinity = 1; // no specific function like secp256k1_ge_set_infinity
}
pFlex->m_Flags = BeamCrypto_FlexPoint_Compact; // restored
}
pFlex->m_Flags |= BeamCrypto_FlexPoint_Ge;
}
void BeamCrypto_FlexPoint_MakeGe_Batch(BeamCrypto_FlexPoint* pFlex, unsigned int nCount)
{
assert(nCount);
static_assert(sizeof(pFlex->m_Ge) >= sizeof(secp256k1_fe), "Ge is used as a temp placeholder for Fe");
#define FLEX_POINT_TEMP_FE(pt) ((secp256k1_fe*) (&(pt).m_Ge))
for (unsigned int i = 0; i < nCount; i++)
{
assert(BeamCrypto_FlexPoint_Gej == pFlex[i].m_Flags);
BatchNormalize_Fwd(FLEX_POINT_TEMP_FE(pFlex[i]), i, &pFlex[i].m_Gej, FLEX_POINT_TEMP_FE(pFlex[i - 1]));
}
secp256k1_fe zDenom;
BatchNormalize_Apex(&zDenom, FLEX_POINT_TEMP_FE(pFlex[nCount - 1]), 1);
for (unsigned int i = nCount; i--; )
{
BatchNormalize_Bwd(FLEX_POINT_TEMP_FE(pFlex[i]), i, &pFlex[i].m_Gej, FLEX_POINT_TEMP_FE(pFlex[i - 1]), &zDenom);
secp256k1_ge_set_gej_normalized(&pFlex[i].m_Ge, &pFlex[i].m_Gej);
pFlex[i].m_Flags = BeamCrypto_FlexPoint_Ge;
}
assert(nCount);
}
void BeamCrypto_MulPoint(BeamCrypto_FlexPoint* pFlex, const BeamCrypto_MultiMac_Secure* pGen, const secp256k1_scalar* pK)
{
BeamCrypto_MultiMac_Context ctx;
ctx.m_pRes = &pFlex->m_Gej;
ctx.m_pZDenom = 0;
ctx.m_Fast = 0;
ctx.m_Secure = 1;
ctx.m_pGenSecure = pGen;
ctx.m_pSecureK = pK;
BeamCrypto_MultiMac_Calculate(&ctx);
pFlex->m_Flags = BeamCrypto_FlexPoint_Gej;
}
void BeamCrypto_MulG(BeamCrypto_FlexPoint* pFlex, const secp256k1_scalar* pK)
{
BeamCrypto_MulPoint(pFlex, &BeamCrypto_Context_get()->m_GenG, pK);
}
void BeamCrypto_Sk2Pk(BeamCrypto_UintBig* pRes, secp256k1_scalar* pK)
{
BeamCrypto_FlexPoint fp;
BeamCrypto_MulG(&fp, pK);
BeamCrypto_FlexPoint_MakeCompact(&fp);
assert(BeamCrypto_FlexPoint_Compact & fp.m_Flags);
*pRes = fp.m_Compact.m_X;
if (fp.m_Compact.m_Y)
secp256k1_scalar_negate(pK, pK);
}
//////////////////////////////
// Oracle
void BeamCrypto_Oracle_Init(BeamCrypto_Oracle* p)
{
secp256k1_sha256_initialize(&p->m_sha);
}
void BeamCrypto_Oracle_Expose(BeamCrypto_Oracle* p, const uint8_t* pPtr, size_t nSize)
{
secp256k1_sha256_write(&p->m_sha, pPtr, nSize);
}
void BeamCrypto_Oracle_NextHash(BeamCrypto_Oracle* p, BeamCrypto_UintBig* pHash)
{
secp256k1_sha256_t sha = p->m_sha; // copy
secp256k1_sha256_finalize(&sha, pHash->m_pVal);
secp256k1_sha256_write(&p->m_sha, pHash->m_pVal, BeamCrypto_nBytes);
}
void BeamCrypto_Oracle_NextScalar(BeamCrypto_Oracle* p, secp256k1_scalar* pS)
{
while (1)
{
BeamCrypto_UintBig hash;
BeamCrypto_Oracle_NextHash(p, &hash);
if (ScalarImportNnz(pS, hash.m_pVal))
break;
}
}
void BeamCrypto_Oracle_NextPoint(BeamCrypto_Oracle* p, BeamCrypto_FlexPoint* pFlex)
{
pFlex->m_Compact.m_Y = 0;
while (1)
{
BeamCrypto_Oracle_NextHash(p, &pFlex->m_Compact.m_X);
pFlex->m_Flags = BeamCrypto_FlexPoint_Compact;
BeamCrypto_FlexPoint_MakeGe(pFlex);
if ((BeamCrypto_FlexPoint_Ge & pFlex->m_Flags) && !secp256k1_ge_is_infinity(&pFlex->m_Ge))
break;
}
}
//////////////////////////////
// CoinID
#define BeamCrypto_CoinID_nSubkeyBits 24
int BeamCrypto_CoinID_getSchemeAndSubkey(const BeamCrypto_CoinID* p, uint8_t* pScheme, uint32_t* pSubkey)
{
*pScheme = (uint8_t) (p->m_SubIdx >> BeamCrypto_CoinID_nSubkeyBits);
*pSubkey = p->m_SubIdx & ((1U << BeamCrypto_CoinID_nSubkeyBits) - 1);
if (!*pSubkey)
return 0; // by convention: up to latest scheme, Subkey=0 - is a master key
if (BeamCrypto_CoinID_Scheme_BB21 == *pScheme)
return 0; // BB2.1 workaround
return 1;
}
#define HASH_WRITE_STR(hash, str) secp256k1_sha256_write(&hash, str, sizeof(str))
void secp256k1_sha256_write_Num(secp256k1_sha256_t* pSha, uint64_t val)
{
int nContinue;
do
{
uint8_t x = (uint8_t)val;
nContinue = (val >= 0x80);
if (nContinue)
{
x |= 0x80;
val >>= 7;
}
secp256k1_sha256_write(pSha, &x, sizeof(x));
} while (nContinue);
}
void secp256k1_sha256_write_CompactPoint(secp256k1_sha256_t* pSha, const BeamCrypto_CompactPoint* pCompact)
{
secp256k1_sha256_write(pSha, pCompact->m_X.m_pVal, sizeof(pCompact->m_X.m_pVal));
secp256k1_sha256_write(pSha, &pCompact->m_Y, sizeof(pCompact->m_Y));
}
void secp256k1_sha256_write_Point(secp256k1_sha256_t* pSha, BeamCrypto_FlexPoint* pFlex)
{
BeamCrypto_FlexPoint_MakeCompact(pFlex);
assert(BeamCrypto_FlexPoint_Compact & pFlex->m_Flags);
secp256k1_sha256_write_CompactPoint(pSha, &pFlex->m_Compact);
}
void BeamCrypto_CoinID_getHash(const BeamCrypto_CoinID* p, BeamCrypto_UintBig* pHash)
{
secp256k1_sha256_t sha;
secp256k1_sha256_initialize(&sha);
uint8_t nScheme;
uint32_t nSubkey;
BeamCrypto_CoinID_getSchemeAndSubkey(p, &nScheme, &nSubkey);
uint32_t nSubIdx = p->m_SubIdx;
switch (nScheme)
{
case BeamCrypto_CoinID_Scheme_BB21:
// this is actually V0, with a workaround
nSubIdx = nSubkey | (BeamCrypto_CoinID_Scheme_V0 << BeamCrypto_CoinID_nSubkeyBits);
nScheme = BeamCrypto_CoinID_Scheme_V0;
// no break;
case BeamCrypto_CoinID_Scheme_V0:
HASH_WRITE_STR(sha, "kid");
break;
default:
HASH_WRITE_STR(sha, "kidv-1");
}
secp256k1_sha256_write_Num(&sha, p->m_Idx);
secp256k1_sha256_write_Num(&sha, p->m_Type);
secp256k1_sha256_write_Num(&sha, nSubIdx);
if (nScheme >= BeamCrypto_CoinID_Scheme_V1)
{
// newer scheme - account for the Value and Asset.
secp256k1_sha256_write_Num(&sha, p->m_Amount);
if (p->m_AssetID)
{
HASH_WRITE_STR(sha, "asset");
secp256k1_sha256_write_Num(&sha, p->m_AssetID);
}
}
secp256k1_sha256_finalize(&sha, pHash->m_pVal);
}
//////////////////////////////
// Kdf
void BeamCrypto_Kdf_Init(BeamCrypto_Kdf* p, const BeamCrypto_UintBig* pSeed)
{
static const char szSalt[] = "beam-HKdf";
BeamCrypto_NonceGenerator ng1, ng2;
BeamCrypto_NonceGenerator_Init(&ng1, szSalt, sizeof(szSalt), pSeed);
ng2 = ng1;
static const char szCtx1[] = "gen";
static const char szCtx2[] = "coF";
ng1.m_pContext = szCtx1;
ng1.m_nContext = sizeof(szCtx1);
BeamCrypto_NonceGenerator_NextOkm(&ng1);
p->m_Secret = ng1.m_Okm;
ng2.m_pContext = szCtx2;
ng2.m_nContext = sizeof(szCtx2);
BeamCrypto_NonceGenerator_NextScalar(&ng2, &p->m_kCoFactor);
SECURE_ERASE_OBJ(ng1);
SECURE_ERASE_OBJ(ng2);
}
void BeamCrypto_Kdf_Derive_PKey(const BeamCrypto_Kdf* p, const BeamCrypto_UintBig* pHv, secp256k1_scalar* pK)
{
static const char szSalt[] = "beam-Key";
BeamCrypto_NonceGenerator ng;
secp256k1_hmac_sha256_t hmac;
BeamCrypto_NonceGenerator_InitBegin(&ng, &hmac, szSalt, sizeof(szSalt));
secp256k1_hmac_sha256_write(&hmac, p->m_Secret.m_pVal, sizeof(p->m_Secret.m_pVal));
secp256k1_hmac_sha256_write(&hmac, pHv->m_pVal, sizeof(pHv->m_pVal));
BeamCrypto_NonceGenerator_InitEnd(&ng, &hmac);
BeamCrypto_NonceGenerator_NextScalar(&ng, pK);
SECURE_ERASE_OBJ(ng);
}
void BeamCrypto_Kdf_Derive_SKey(const BeamCrypto_Kdf* p, const BeamCrypto_UintBig* pHv, secp256k1_scalar* pK)
{
BeamCrypto_Kdf_Derive_PKey(p, pHv, pK);
secp256k1_scalar_mul(pK, pK, &p->m_kCoFactor);
}
#define ARRAY_ELEMENT_SAFE(arr, index) ((arr)[(((index) < _countof(arr)) ? (index) : (_countof(arr) - 1))])
#define FOURCC_FROM_BYTES(a, b, c, d) (((((((uint32_t) a << 8) | (uint32_t) b) << 8) | (uint32_t) c) << 8) | (uint32_t) d)
#define FOURCC_FROM_STR(name) FOURCC_FROM_BYTES(ARRAY_ELEMENT_SAFE(#name,0), ARRAY_ELEMENT_SAFE(#name,1), ARRAY_ELEMENT_SAFE(#name,2), ARRAY_ELEMENT_SAFE(#name,3))
void BeamCrypto_Kdf_getChild(BeamCrypto_Kdf* p, uint32_t iChild, const BeamCrypto_Kdf* pParent)
{
secp256k1_sha256_t sha;
secp256k1_sha256_initialize(&sha);
HASH_WRITE_STR(sha, "kid");
const uint32_t nType = FOURCC_FROM_STR(SubK);
secp256k1_sha256_write_Num(&sha, iChild);
secp256k1_sha256_write_Num(&sha, nType);
secp256k1_sha256_write_Num(&sha, 0);
BeamCrypto_UintBig hv;
secp256k1_sha256_finalize(&sha, hv.m_pVal);
secp256k1_scalar sk;
BeamCrypto_Kdf_Derive_SKey(pParent, &hv, &sk);
secp256k1_scalar_get_b32(hv.m_pVal, &sk);
SECURE_ERASE_OBJ(sk);
BeamCrypto_Kdf_Init(p, &hv);
SECURE_ERASE_OBJ(hv);
}
//////////////////////////////
// Kdf - CoinID key derivation
void BeamCrypto_CoinID_getSk(const BeamCrypto_Kdf* pKdf, const BeamCrypto_CoinID* pCid, secp256k1_scalar* pK)
{
BeamCrypto_CoinID_getSkComm(pKdf, pCid, pK, 0);
}
void BeamCrypto_CoinID_getSkComm(const BeamCrypto_Kdf* pKdf, const BeamCrypto_CoinID* pCid, secp256k1_scalar* pK, BeamCrypto_FlexPoint* pComm)
{
BeamCrypto_FlexPoint pFlex[2];
union
{
// save some space
struct
{
uint8_t nScheme;
uint32_t nSubkey;
BeamCrypto_UintBig hv;
BeamCrypto_Kdf kdfC;
} k;
struct
{
BeamCrypto_Oracle oracle;
secp256k1_scalar k1;
} o;
struct
{
BeamCrypto_MultiMac_Scalar s;
BeamCrypto_MultiMac_WNaf wnaf;
BeamCrypto_MultiMac_Fast genAsset;
secp256k1_fe zDenom;
} mm;
} u;
int nChild = BeamCrypto_CoinID_getSchemeAndSubkey(pCid, &u.k.nScheme, &u.k.nSubkey);
if (nChild)
{
BeamCrypto_Kdf_getChild(&u.k.kdfC, u.k.nSubkey, pKdf);
pKdf = &u.k.kdfC;
}
BeamCrypto_CoinID_getHash(pCid, &u.k.hv);
BeamCrypto_Kdf_Derive_SKey(pKdf, &u.k.hv, pK);
if (nChild)
SECURE_ERASE_OBJ(u.k.kdfC);
BeamCrypto_Context* pCtx = BeamCrypto_Context_get();
// sk*G + v*H
BeamCrypto_MultiMac_Context mmCtx;
mmCtx.m_pRes = &pFlex[0].m_Gej;
mmCtx.m_Secure = 1;
mmCtx.m_pSecureK = pK;
mmCtx.m_pGenSecure = &pCtx->m_GenG;
mmCtx.m_Fast = 1;
mmCtx.m_pS = &u.mm.s;
mmCtx.m_pWnaf = &u.mm.wnaf;
if (pCid->m_AssetID)
{
// derive asset gen
BeamCrypto_Oracle_Init(&u.o.oracle);
HASH_WRITE_STR(u.o.oracle.m_sha, "B.Asset.Gen.V1");
secp256k1_sha256_write_Num(&u.o.oracle.m_sha, pCid->m_AssetID);
BeamCrypto_FlexPoint fpAsset;
BeamCrypto_Oracle_NextPoint(&u.o.oracle, &fpAsset);
mmCtx.m_pGenFast = &u.mm.genAsset;
mmCtx.m_pZDenom = &u.mm.zDenom;
BeamCrypto_MultiMac_SetCustom_Nnz(&mmCtx, &fpAsset);
}
else
{
mmCtx.m_pGenFast = pCtx->m_pGenFast + BeamCrypto_MultiMac_Fast_Idx_H;
mmCtx.m_pZDenom = 0;
}
secp256k1_scalar_set_u64(u.mm.s.m_pK, pCid->m_Amount);
BeamCrypto_MultiMac_Calculate(&mmCtx);
pFlex[0].m_Flags = BeamCrypto_FlexPoint_Gej;
// sk * J
mmCtx.m_pRes = &pFlex[1].m_Gej;
mmCtx.m_pGenSecure = &pCtx->m_GenJ;
mmCtx.m_pZDenom = 0;
mmCtx.m_Fast = 0;
BeamCrypto_MultiMac_Calculate(&mmCtx);
pFlex[1].m_Flags = BeamCrypto_FlexPoint_Gej;
// adjust sk
BeamCrypto_FlexPoint_MakeGe_Batch(pFlex, _countof(pFlex));
BeamCrypto_Oracle_Init(&u.o.oracle);
for (unsigned int i = 0; i < _countof(pFlex); i++)
secp256k1_sha256_write_Point(&u.o.oracle.m_sha, pFlex + i);
BeamCrypto_Oracle_NextScalar(&u.o.oracle, &u.o.k1);
secp256k1_scalar_add(pK, pK, &u.o.k1);
if (pComm)
{
mmCtx.m_pGenSecure = &pCtx->m_GenG; // not really secure here, just no good reason to have additional non-secure J-gen
mmCtx.m_pSecureK = &u.o.k1;
BeamCrypto_MultiMac_Calculate(&mmCtx);
pFlex[1].m_Flags = BeamCrypto_FlexPoint_Gej;
assert(BeamCrypto_FlexPoint_Ge & pFlex[0].m_Flags);
secp256k1_gej_add_ge_var(&pComm->m_Gej, &pFlex[1].m_Gej, &pFlex[0].m_Ge, 0);
pComm->m_Flags = BeamCrypto_FlexPoint_Gej;
}
}
//////////////////////////////
// RangeProof
static void WriteInNetworkOrder(uint8_t** ppDst, uint64_t val, unsigned int nLen)
{
for (unsigned int i = 0; i < nLen; i++, val >>= 8)
{
--*ppDst;
**ppDst = (uint8_t) val;
}
}
typedef struct
{
BeamCrypto_RangeProof* m_pRangeProof;
BeamCrypto_NonceGenerator m_NonceGen; // 88 bytes