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Merge #486: Add pippenger_wnaf for multi-multiplication

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d2f9c6b Use more precise pippenger bucket windows (Jonas Nick)
4c950bb Save some additions per window in _pippenger_wnaf (Peter Dettman)
a58f543 Add flags for choosing algorithm in ecmult_multi benchmark (Jonas Nick)
36b22c9 Use scratch space dependent batching in ecmult_multi (Jonas Nick)
355a38f Add pippenger_wnaf ecmult_multi (Jonas Nick)
bc65aa7 Add bench_ecmult (Pieter Wuille)
dba5471 Add ecmult_multi tests (Andrew Poelstra)
8c1c831 Generalize Strauss to support multiple points (Pieter Wuille)
548de42 add resizeable scratch space API (Andrew Poelstra)

Pull request description:

  This PR is based on #473 and adds a variant of "Pippengers algorithm" (see [Bernstein et al., Faster batch forgery identification](https://eprint.iacr.org/2012/549.pdf), page 15 and https://github.com/scipr-lab/libff/pull/10) for point multi-multiplication that performs better with a large number of points than Strauss' algorithm.

  ![aggsig](https://user-images.githubusercontent.com/2582071/32731185-12c0f108-c881-11e7-83c7-c2432b5fadf5.png)

  Thanks to @sipa for providing `wnaf_fixed`, benchmarking, and the crucial suggestion to use affine addition.

  The PR also makes `ecmult_multi` decide which algorithm to use, based on the number of points and the available scratch space.
  For restricted scratch spaces this can be further optimized in the future (f.e. a 35kB scratch space allows batches of 11 points with strauss or 95 points with pippenger; choosing pippenger would be 5% faster).

  As soon as this PR has received some feedback I'll repeat the benchmarks to determine the optimal `pippenger_bucket_window` with the new benchmarking code in #473.

Tree-SHA512: 8e155107a00d35f412300275803f912b1d228b7adff578bc4754c5b29641100b51b9d37f989316b636f7144e6b199febe7de302a44f498bbfd8d463bdbe31a5c
This commit is contained in:
Pieter Wuille 2017-12-07 16:46:30 -08:00
commit c77fc08597
No known key found for this signature in database
GPG Key ID: A636E97631F767E0
16 changed files with 1600 additions and 82 deletions
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8
Makefile.am
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@ -42,6 +42,8 @@ noinst_HEADERS += src/field_5x52_asm_impl.h
noinst_HEADERS += src/java/org_bitcoin_NativeSecp256k1.h noinst_HEADERS += src/java/org_bitcoin_NativeSecp256k1.h
noinst_HEADERS += src/java/org_bitcoin_Secp256k1Context.h noinst_HEADERS += src/java/org_bitcoin_Secp256k1Context.h
noinst_HEADERS += src/util.h noinst_HEADERS += src/util.h
noinst_HEADERS += src/scratch.h
noinst_HEADERS += src/scratch_impl.h
noinst_HEADERS += src/testrand.h noinst_HEADERS += src/testrand.h
noinst_HEADERS += src/testrand_impl.h noinst_HEADERS += src/testrand_impl.h
noinst_HEADERS += src/hash.h noinst_HEADERS += src/hash.h
@ -79,7 +81,7 @@ libsecp256k1_jni_la_CPPFLAGS = -DSECP256K1_BUILD $(JNI_INCLUDES)
noinst_PROGRAMS = noinst_PROGRAMS =
if USE_BENCHMARK if USE_BENCHMARK
noinst_PROGRAMS += bench_verify bench_sign bench_internal noinst_PROGRAMS += bench_verify bench_sign bench_internal bench_ecmult
bench_verify_SOURCES = src/bench_verify.c bench_verify_SOURCES = src/bench_verify.c
bench_verify_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB) bench_verify_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
bench_sign_SOURCES = src/bench_sign.c bench_sign_SOURCES = src/bench_sign.c
@ -87,6 +89,9 @@ bench_sign_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
bench_internal_SOURCES = src/bench_internal.c bench_internal_SOURCES = src/bench_internal.c
bench_internal_LDADD = $(SECP_LIBS) $(COMMON_LIB) bench_internal_LDADD = $(SECP_LIBS) $(COMMON_LIB)
bench_internal_CPPFLAGS = -DSECP256K1_BUILD $(SECP_INCLUDES) bench_internal_CPPFLAGS = -DSECP256K1_BUILD $(SECP_INCLUDES)
bench_ecmult_SOURCES = src/bench_ecmult.c
bench_ecmult_LDADD = $(SECP_LIBS) $(COMMON_LIB)
bench_ecmult_CPPFLAGS = -DSECP256K1_BUILD $(SECP_INCLUDES)
endif endif
TESTS = TESTS =
@ -159,6 +164,7 @@ $(gen_context_BIN): $(gen_context_OBJECTS)
$(libsecp256k1_la_OBJECTS): src/ecmult_static_context.h $(libsecp256k1_la_OBJECTS): src/ecmult_static_context.h
$(tests_OBJECTS): src/ecmult_static_context.h $(tests_OBJECTS): src/ecmult_static_context.h
$(bench_internal_OBJECTS): src/ecmult_static_context.h $(bench_internal_OBJECTS): src/ecmult_static_context.h
$(bench_ecmult_OBJECTS): src/ecmult_static_context.h
src/ecmult_static_context.h: $(gen_context_BIN) src/ecmult_static_context.h: $(gen_context_BIN)
./$(gen_context_BIN) ./$(gen_context_BIN)

35
include/secp256k1.h
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@ -42,6 +42,19 @@ extern "C" {
*/ */
typedef struct secp256k1_context_struct secp256k1_context; typedef struct secp256k1_context_struct secp256k1_context;
/** Opaque data structure that holds rewriteable "scratch space"
*
* The purpose of this structure is to replace dynamic memory allocations,
* because we target architectures where this may not be available. It is
* essentially a resizable (within specified parameters) block of bytes,
* which is initially created either by memory allocation or TODO as a pointer
* into some fixed rewritable space.
*
* Unlike the context object, this cannot safely be shared between threads
* without additional synchronization logic.
*/
typedef struct secp256k1_scratch_space_struct secp256k1_scratch_space;
/** Opaque data structure that holds a parsed and valid public key. /** Opaque data structure that holds a parsed and valid public key.
* *
* The exact representation of data inside is implementation defined and not * The exact representation of data inside is implementation defined and not
@ -243,6 +256,28 @@ SECP256K1_API void secp256k1_context_set_error_callback(
const void* data const void* data
) SECP256K1_ARG_NONNULL(1); ) SECP256K1_ARG_NONNULL(1);
/** Create a secp256k1 scratch space object.
*
* Returns: a newly created scratch space.
* Args: ctx: an existing context object (cannot be NULL)
* In: init_size: initial amount of memory to allocate
* max_size: maximum amount of memory to allocate
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space* secp256k1_scratch_space_create(
const secp256k1_context* ctx,
size_t init_size,
size_t max_size
) SECP256K1_ARG_NONNULL(1);
/** Destroy a secp256k1 scratch space.
*
* The pointer may not be used afterwards.
* Args: scratch: space to destroy
*/
SECP256K1_API void secp256k1_scratch_space_destroy(
secp256k1_scratch_space* scratch
);
/** Parse a variable-length public key into the pubkey object. /** Parse a variable-length public key into the pubkey object.
* *
* Returns: 1 if the public key was fully valid. * Returns: 1 if the public key was fully valid.

16
src/bench.h
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@ -8,6 +8,7 @@
#define SECP256K1_BENCH_H #define SECP256K1_BENCH_H
#include <stdio.h> #include <stdio.h>
#include <string.h>
#include <math.h> #include <math.h>
#include "sys/time.h" #include "sys/time.h"
@ -63,4 +64,19 @@ void run_benchmark(char *name, void (*benchmark)(void*), void (*setup)(void*), v
printf("us\n"); printf("us\n");
} }
int have_flag(int argc, char** argv, char *flag) {
char** argm = argv + argc;
argv++;
if (argv == argm) {
return 1;
}
while (argv != NULL && argv != argm) {
if (strcmp(*argv, flag) == 0) {
return 1;
}
argv++;
}
return 0;
}
#endif /* SECP256K1_BENCH_H */ #endif /* SECP256K1_BENCH_H */

196
src/bench_ecmult.c Normal file
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@ -0,0 +1,196 @@
/**********************************************************************
* Copyright (c) 2017 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#include <stdio.h>
#include "include/secp256k1.h"
#include "util.h"
#include "hash_impl.h"
#include "num_impl.h"
#include "field_impl.h"
#include "group_impl.h"
#include "scalar_impl.h"
#include "ecmult_impl.h"
#include "bench.h"
#include "secp256k1.c"
#define POINTS 32768
#define ITERS 10000
typedef struct {
/* Setup once in advance */
secp256k1_context* ctx;
secp256k1_scratch_space* scratch;
secp256k1_scalar* scalars;
secp256k1_ge* pubkeys;
secp256k1_scalar* seckeys;
secp256k1_gej* expected_output;
secp256k1_ecmult_multi_func ecmult_multi;
/* Changes per test */
size_t count;
int includes_g;
/* Changes per test iteration */
size_t offset1;
size_t offset2;
/* Test output. */
secp256k1_gej* output;
} bench_data;
static int bench_callback(secp256k1_scalar* sc, secp256k1_ge* ge, size_t idx, void* arg) {
bench_data* data = (bench_data*)arg;
if (data->includes_g) ++idx;
if (idx == 0) {
*sc = data->scalars[data->offset1];
*ge = secp256k1_ge_const_g;
} else {
*sc = data->scalars[(data->offset1 + idx) % POINTS];
*ge = data->pubkeys[(data->offset2 + idx - 1) % POINTS];
}
return 1;
}
static void bench_ecmult(void* arg) {
bench_data* data = (bench_data*)arg;
size_t count = data->count;
int includes_g = data->includes_g;
size_t iters = 1 + ITERS / count;
size_t iter;
for (iter = 0; iter < iters; ++iter) {
data->ecmult_multi(&data->ctx->ecmult_ctx, data->scratch, &data->output[iter], data->includes_g ? &data->scalars[data->offset1] : NULL, bench_callback, arg, count - includes_g);
data->offset1 = (data->offset1 + count) % POINTS;
data->offset2 = (data->offset2 + count - 1) % POINTS;
}
}
static void bench_ecmult_setup(void* arg) {
bench_data* data = (bench_data*)arg;
data->offset1 = (data->count * 0x537b7f6f + 0x8f66a481) % POINTS;
data->offset2 = (data->count * 0x7f6f537b + 0x6a1a8f49) % POINTS;
}
static void bench_ecmult_teardown(void* arg) {
bench_data* data = (bench_data*)arg;
size_t iters = 1 + ITERS / data->count;
size_t iter;
/* Verify the results in teardown, to avoid doing comparisons while benchmarking. */
for (iter = 0; iter < iters; ++iter) {
secp256k1_gej tmp;
secp256k1_gej_add_var(&tmp, &data->output[iter], &data->expected_output[iter], NULL);
CHECK(secp256k1_gej_is_infinity(&tmp));
}
}
static void generate_scalar(uint32_t num, secp256k1_scalar* scalar) {
secp256k1_sha256 sha256;
unsigned char c[11] = {'e', 'c', 'm', 'u', 'l', 't', 0, 0, 0, 0};
unsigned char buf[32];
int overflow = 0;
c[6] = num;
c[7] = num >> 8;
c[8] = num >> 16;
c[9] = num >> 24;
secp256k1_sha256_initialize(&sha256);
secp256k1_sha256_write(&sha256, c, sizeof(c));
secp256k1_sha256_finalize(&sha256, buf);
secp256k1_scalar_set_b32(scalar, buf, &overflow);
CHECK(!overflow);
}
static void run_test(bench_data* data, size_t count, int includes_g) {
char str[32];
static const secp256k1_scalar zero = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 0);
size_t iters = 1 + ITERS / count;
size_t iter;
data->count = count;
data->includes_g = includes_g;
/* Compute (the negation of) the expected results directly. */
data->offset1 = (data->count * 0x537b7f6f + 0x8f66a481) % POINTS;
data->offset2 = (data->count * 0x7f6f537b + 0x6a1a8f49) % POINTS;
for (iter = 0; iter < iters; ++iter) {
secp256k1_scalar tmp;
secp256k1_scalar total = data->scalars[(data->offset1++) % POINTS];
size_t i = 0;
for (i = 0; i + 1 < count; ++i) {
secp256k1_scalar_mul(&tmp, &data->seckeys[(data->offset2++) % POINTS], &data->scalars[(data->offset1++) % POINTS]);
secp256k1_scalar_add(&total, &total, &tmp);
}
secp256k1_scalar_negate(&total, &total);
secp256k1_ecmult(&data->ctx->ecmult_ctx, &data->expected_output[iter], NULL, &zero, &total);
}
/* Run the benchmark. */
sprintf(str, includes_g ? "ecmult_%ig" : "ecmult_%i", (int)count);
run_benchmark(str, bench_ecmult, bench_ecmult_setup, bench_ecmult_teardown, data, 10, count * (1 + ITERS / count));
}
int main(int argc, char **argv) {
bench_data data;
int i, p;
secp256k1_gej* pubkeys_gej;
size_t scratch_size;
if (argc > 1) {
if(have_flag(argc, argv, "pippenger_wnaf")) {
printf("Using pippenger_wnaf:\n");
data.ecmult_multi = secp256k1_ecmult_pippenger_batch_single;
} else if(have_flag(argc, argv, "strauss_wnaf")) {
printf("Using strauss_wnaf:\n");
data.ecmult_multi = secp256k1_ecmult_strauss_batch_single;
}
} else {
data.ecmult_multi = secp256k1_ecmult_multi_var;
}
/* Allocate stuff */
data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
scratch_size = secp256k1_strauss_scratch_size(POINTS) + STRAUSS_SCRATCH_OBJECTS*16;
data.scratch = secp256k1_scratch_space_create(data.ctx, scratch_size, scratch_size);
data.scalars = malloc(sizeof(secp256k1_scalar) * POINTS);
data.seckeys = malloc(sizeof(secp256k1_scalar) * POINTS);
data.pubkeys = malloc(sizeof(secp256k1_ge) * POINTS);
data.expected_output = malloc(sizeof(secp256k1_gej) * (ITERS + 1));
data.output = malloc(sizeof(secp256k1_gej) * (ITERS + 1));
/* Generate a set of scalars, and private/public keypairs. */
pubkeys_gej = malloc(sizeof(secp256k1_gej) * POINTS);
secp256k1_gej_set_ge(&pubkeys_gej[0], &secp256k1_ge_const_g);
secp256k1_scalar_set_int(&data.seckeys[0], 1);
for (i = 0; i < POINTS; ++i) {
generate_scalar(i, &data.scalars[i]);
if (i) {
secp256k1_gej_double_var(&pubkeys_gej[i], &pubkeys_gej[i - 1], NULL);
secp256k1_scalar_add(&data.seckeys[i], &data.seckeys[i - 1], &data.seckeys[i - 1]);
}
}
secp256k1_ge_set_all_gej_var(data.pubkeys, pubkeys_gej, POINTS, &data.ctx->error_callback);
free(pubkeys_gej);
for (i = 1; i <= 8; ++i) {
run_test(&data, i, 1);
}
for (p = 0; p <= 11; ++p) {
for (i = 9; i <= 16; ++i) {
run_test(&data, i << p, 1);
}
}
secp256k1_context_destroy(data.ctx);
secp256k1_scratch_space_destroy(data.scratch);
free(data.scalars);
free(data.pubkeys);
free(data.seckeys);
free(data.output);
free(data.expected_output);
return(0);
}

15
src/bench_internal.c
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@ -324,21 +324,6 @@ void bench_num_jacobi(void* arg) {
} }
#endif #endif
int have_flag(int argc, char** argv, char *flag) {
char** argm = argv + argc;
argv++;
if (argv == argm) {
return 1;
}
while (argv != NULL && argv != argm) {
if (strcmp(*argv, flag) == 0) {
return 1;
}
argv++;
}
return 0;
}
int main(int argc, char **argv) { int main(int argc, char **argv) {
bench_inv data; bench_inv data;
if (have_flag(argc, argv, "scalar") || have_flag(argc, argv, "add")) run_benchmark("scalar_add", bench_scalar_add, bench_setup, NULL, &data, 10, 2000000); if (have_flag(argc, argv, "scalar") || have_flag(argc, argv, "add")) run_benchmark("scalar_add", bench_scalar_add, bench_setup, NULL, &data, 10, 2000000);

18
src/ecmult.h
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@ -1,5 +1,5 @@
/********************************************************************** /**********************************************************************
* Copyright (c) 2013, 2014 Pieter Wuille * * Copyright (c) 2013, 2014, 2017 Pieter Wuille, Andrew Poelstra *
* Distributed under the MIT software license, see the accompanying * * Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.* * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/ **********************************************************************/
@ -9,6 +9,8 @@
#include "num.h" #include "num.h"
#include "group.h" #include "group.h"
#include "scalar.h"
#include "scratch.h"
typedef struct { typedef struct {
/* For accelerating the computation of a*P + b*G: */ /* For accelerating the computation of a*P + b*G: */
@ -28,4 +30,18 @@ static int secp256k1_ecmult_context_is_built(const secp256k1_ecmult_context *ctx
/** Double multiply: R = na*A + ng*G */ /** Double multiply: R = na*A + ng*G */
static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng); static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng);
typedef int (secp256k1_ecmult_multi_callback)(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data);
/**
* Multi-multiply: R = inp_g_sc * G + sum_i ni * Ai.
* Chooses the right algorithm for a given number of points and scratch space
* size. Resets and overwrites the given scratch space. If the points do not
* fit in the scratch space the algorithm is repeatedly run with batches of
* points.
* Returns: 1 on success (including when inp_g_sc is NULL and n is 0)
* 0 if there is not enough scratch space for a single point or
* callback returns 0
*/
static int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
#endif /* SECP256K1_ECMULT_H */ #endif /* SECP256K1_ECMULT_H */

7
src/ecmult_const_impl.h
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@ -12,13 +12,6 @@
#include "ecmult_const.h" #include "ecmult_const.h"
#include "ecmult_impl.h" #include "ecmult_impl.h"
#ifdef USE_ENDOMORPHISM
#define WNAF_BITS 128
#else
#define WNAF_BITS 256
#endif
#define WNAF_SIZE(w) ((WNAF_BITS + (w) - 1) / (w))
/* This is like `ECMULT_TABLE_GET_GE` but is constant time */ /* This is like `ECMULT_TABLE_GET_GE` but is constant time */
#define ECMULT_CONST_TABLE_GET_GE(r,pre,n,w) do { \ #define ECMULT_CONST_TABLE_GET_GE(r,pre,n,w) do { \
int m; \ int m; \

721
src/ecmult_impl.h
View File

@ -1,13 +1,14 @@
/********************************************************************** /*****************************************************************************
* Copyright (c) 2013, 2014 Pieter Wuille * * Copyright (c) 2013, 2014, 2017 Pieter Wuille, Andrew Poelstra, Jonas Nick *
* Distributed under the MIT software license, see the accompanying * * Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.* * file COPYING or http://www.opensource.org/licenses/mit-license.php. *
**********************************************************************/ *****************************************************************************/
#ifndef SECP256K1_ECMULT_IMPL_H #ifndef SECP256K1_ECMULT_IMPL_H
#define SECP256K1_ECMULT_IMPL_H #define SECP256K1_ECMULT_IMPL_H
#include <string.h> #include <string.h>
#include <stdint.h>
#include "group.h" #include "group.h"
#include "scalar.h" #include "scalar.h"
@ -41,9 +42,35 @@
#endif #endif
#endif #endif
#ifdef USE_ENDOMORPHISM
#define WNAF_BITS 128
#else
#define WNAF_BITS 256
#endif
#define WNAF_SIZE(w) ((WNAF_BITS + (w) - 1) / (w))
/** The number of entries a table with precomputed multiples needs to have. */ /** The number of entries a table with precomputed multiples needs to have. */
#define ECMULT_TABLE_SIZE(w) (1 << ((w)-2)) #define ECMULT_TABLE_SIZE(w) (1 << ((w)-2))
/* The number of objects allocated on the scratch space for ecmult_multi algorithms */
#define PIPPENGER_SCRATCH_OBJECTS 6
#define STRAUSS_SCRATCH_OBJECTS 6
#define PIPPENGER_MAX_BUCKET_WINDOW 12
/* Minimum number of points for which pippenger_wnaf is faster than strauss wnaf */
#ifdef USE_ENDOMORPHISM
#define ECMULT_PIPPENGER_THRESHOLD 88
#else
#define ECMULT_PIPPENGER_THRESHOLD 160
#endif
#ifdef USE_ENDOMORPHISM
#define ECMULT_MAX_POINTS_PER_BATCH 5000000
#else
#define ECMULT_MAX_POINTS_PER_BATCH 10000000
#endif
/** Fill a table 'prej' with precomputed odd multiples of a. Prej will contain /** Fill a table 'prej' with precomputed odd multiples of a. Prej will contain
* the values [1*a,3*a,...,(2*n-1)*a], so it space for n values. zr[0] will * the values [1*a,3*a,...,(2*n-1)*a], so it space for n values. zr[0] will
* contain prej[0].z / a.z. The other zr[i] values = prej[i].z / prej[i-1].z. * contain prej[0].z / a.z. The other zr[i] values = prej[i].z / prej[i-1].z.
@ -283,50 +310,78 @@ static int secp256k1_ecmult_wnaf(int *wnaf, int len, const secp256k1_scalar *a,
return last_set_bit + 1; return last_set_bit + 1;
} }
static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng) { struct secp256k1_strauss_point_state {
secp256k1_ge pre_a[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_ge tmpa;
secp256k1_fe Z;
#ifdef USE_ENDOMORPHISM #ifdef USE_ENDOMORPHISM
secp256k1_ge pre_a_lam[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_scalar na_1, na_lam; secp256k1_scalar na_1, na_lam;
/* Splitted G factors. */
secp256k1_scalar ng_1, ng_128;
int wnaf_na_1[130]; int wnaf_na_1[130];
int wnaf_na_lam[130]; int wnaf_na_lam[130];
int bits_na_1; int bits_na_1;
int bits_na_lam; int bits_na_lam;
int wnaf_ng_1[129];
int bits_ng_1;
int wnaf_ng_128[129];
int bits_ng_128;
#else #else
int wnaf_na[256]; int wnaf_na[256];
int bits_na; int bits_na;
#endif
size_t input_pos;
};
struct secp256k1_strauss_state {
secp256k1_gej* prej;
secp256k1_fe* zr;
secp256k1_ge* pre_a;
#ifdef USE_ENDOMORPHISM
secp256k1_ge* pre_a_lam;
#endif
struct secp256k1_strauss_point_state* ps;
};
static void secp256k1_ecmult_strauss_wnaf(const secp256k1_ecmult_context *ctx, const struct secp256k1_strauss_state *state, secp256k1_gej *r, int num, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng) {
secp256k1_ge tmpa;
secp256k1_fe Z;
#ifdef USE_ENDOMORPHISM
/* Splitted G factors. */
secp256k1_scalar ng_1, ng_128;
int wnaf_ng_1[129];
int bits_ng_1 = 0;
int wnaf_ng_128[129];
int bits_ng_128 = 0;
#else
int wnaf_ng[256]; int wnaf_ng[256];
int bits_ng; int bits_ng = 0;
#endif #endif
int i; int i;
int bits; int bits = 0;
int np;
int no = 0;
for (np = 0; np < num; ++np) {
if (secp256k1_scalar_is_zero(&na[np]) || secp256k1_gej_is_infinity(&a[np])) {
continue;
}
state->ps[no].input_pos = np;
#ifdef USE_ENDOMORPHISM #ifdef USE_ENDOMORPHISM
/* split na into na_1 and na_lam (where na = na_1 + na_lam*lambda, and na_1 and na_lam are ~128 bit) */ /* split na into na_1 and na_lam (where na = na_1 + na_lam*lambda, and na_1 and na_lam are ~128 bit) */
secp256k1_scalar_split_lambda(&na_1, &na_lam, na); secp256k1_scalar_split_lambda(&state->ps[no].na_1, &state->ps[no].na_lam, &na[np]);
/* build wnaf representation for na_1 and na_lam. */ /* build wnaf representation for na_1 and na_lam. */
bits_na_1 = secp256k1_ecmult_wnaf(wnaf_na_1, 130, &na_1, WINDOW_A); state->ps[no].bits_na_1 = secp256k1_ecmult_wnaf(state->ps[no].wnaf_na_1, 130, &state->ps[no].na_1, WINDOW_A);
bits_na_lam = secp256k1_ecmult_wnaf(wnaf_na_lam, 130, &na_lam, WINDOW_A); state->ps[no].bits_na_lam = secp256k1_ecmult_wnaf(state->ps[no].wnaf_na_lam, 130, &state->ps[no].na_lam, WINDOW_A);
VERIFY_CHECK(bits_na_1 <= 130); VERIFY_CHECK(state->ps[no].bits_na_1 <= 130);
VERIFY_CHECK(bits_na_lam <= 130); VERIFY_CHECK(state->ps[no].bits_na_lam <= 130);
bits = bits_na_1; if (state->ps[no].bits_na_1 > bits) {
if (bits_na_lam > bits) { bits = state->ps[no].bits_na_1;
bits = bits_na_lam; }
} if (state->ps[no].bits_na_lam > bits) {
bits = state->ps[no].bits_na_lam;
}
#else #else
/* build wnaf representation for na. */ /* build wnaf representation for na. */
bits_na = secp256k1_ecmult_wnaf(wnaf_na, 256, na, WINDOW_A); state->ps[no].bits_na = secp256k1_ecmult_wnaf(state->ps[no].wnaf_na, 256, &na[np], WINDOW_A);
bits = bits_na; if (state->ps[no].bits_na > bits) {
bits = state->ps[no].bits_na;
}
#endif #endif
++no;
}
/* Calculate odd multiples of a. /* Calculate odd multiples of a.
* All multiples are brought to the same Z 'denominator', which is stored * All multiples are brought to the same Z 'denominator', which is stored
@ -338,29 +393,51 @@ static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej
* of 1/Z, so we can use secp256k1_gej_add_zinv_var, which uses the same * of 1/Z, so we can use secp256k1_gej_add_zinv_var, which uses the same
* isomorphism to efficiently add with a known Z inverse. * isomorphism to efficiently add with a known Z inverse.
*/ */
secp256k1_ecmult_odd_multiples_table_globalz_windowa(pre_a, &Z, a); if (no > 0) {
/* Compute the odd multiples in Jacobian form. */
secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), state->prej, state->zr, &a[state->ps[0].input_pos]);
for (np = 1; np < no; ++np) {
secp256k1_gej tmp = a[state->ps[np].input_pos];
#ifdef VERIFY
secp256k1_fe_normalize_var(&(state->prej[(np - 1) * ECMULT_TABLE_SIZE(WINDOW_A) + ECMULT_TABLE_SIZE(WINDOW_A) - 1].z));
#endif
secp256k1_gej_rescale(&tmp, &(state->prej[(np - 1) * ECMULT_TABLE_SIZE(WINDOW_A) + ECMULT_TABLE_SIZE(WINDOW_A) - 1].z));
secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), state->prej + np * ECMULT_TABLE_SIZE(WINDOW_A), state->zr + np * ECMULT_TABLE_SIZE(WINDOW_A), &tmp);
secp256k1_fe_mul(state->zr + np * ECMULT_TABLE_SIZE(WINDOW_A), state->zr + np * ECMULT_TABLE_SIZE(WINDOW_A), &(a[state->ps[np].input_pos].z));
}
/* Bring them to the same Z denominator. */
secp256k1_ge_globalz_set_table_gej(ECMULT_TABLE_SIZE(WINDOW_A) * no, state->pre_a, &Z, state->prej, state->zr);
} else {
secp256k1_fe_set_int(&Z, 1);
}
#ifdef USE_ENDOMORPHISM #ifdef USE_ENDOMORPHISM
for (i = 0; i < ECMULT_TABLE_SIZE(WINDOW_A); i++) { for (np = 0; np < no; ++np) {
secp256k1_ge_mul_lambda(&pre_a_lam[i], &pre_a[i]); for (i = 0; i < ECMULT_TABLE_SIZE(WINDOW_A); i++) {
secp256k1_ge_mul_lambda(&state->pre_a_lam[np * ECMULT_TABLE_SIZE(WINDOW_A) + i], &state->pre_a[np * ECMULT_TABLE_SIZE(WINDOW_A) + i]);
}
} }
/* split ng into ng_1 and ng_128 (where gn = gn_1 + gn_128*2^128, and gn_1 and gn_128 are ~128 bit) */ if (ng) {
secp256k1_scalar_split_128(&ng_1, &ng_128, ng); /* split ng into ng_1 and ng_128 (where gn = gn_1 + gn_128*2^128, and gn_1 and gn_128 are ~128 bit) */
secp256k1_scalar_split_128(&ng_1, &ng_128, ng);
/* Build wnaf representation for ng_1 and ng_128 */ /* Build wnaf representation for ng_1 and ng_128 */
bits_ng_1 = secp256k1_ecmult_wnaf(wnaf_ng_1, 129, &ng_1, WINDOW_G); bits_ng_1 = secp256k1_ecmult_wnaf(wnaf_ng_1, 129, &ng_1, WINDOW_G);
bits_ng_128 = secp256k1_ecmult_wnaf(wnaf_ng_128, 129, &ng_128, WINDOW_G); bits_ng_128 = secp256k1_ecmult_wnaf(wnaf_ng_128, 129, &ng_128, WINDOW_G);
if (bits_ng_1 > bits) { if (bits_ng_1 > bits) {
bits = bits_ng_1; bits = bits_ng_1;
} }
if (bits_ng_128 > bits) { if (bits_ng_128 > bits) {
bits = bits_ng_128; bits = bits_ng_128;
}
} }
#else #else
bits_ng = secp256k1_ecmult_wnaf(wnaf_ng, 256, ng, WINDOW_G); if (ng) {
if (bits_ng > bits) { bits_ng = secp256k1_ecmult_wnaf(wnaf_ng, 256, ng, WINDOW_G);
bits = bits_ng; if (bits_ng > bits) {
bits = bits_ng;
}
} }
#endif #endif
@ -370,13 +447,15 @@ static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej
int n; int n;
secp256k1_gej_double_var(r, r, NULL); secp256k1_gej_double_var(r, r, NULL);
#ifdef USE_ENDOMORPHISM #ifdef USE_ENDOMORPHISM
if (i < bits_na_1 && (n = wnaf_na_1[i])) { for (np = 0; np < no; ++np) {
ECMULT_TABLE_GET_GE(&tmpa, pre_a, n, WINDOW_A); if (i < state->ps[np].bits_na_1 && (n = state->ps[np].wnaf_na_1[i])) {
secp256k1_gej_add_ge_var(r, r, &tmpa, NULL); ECMULT_TABLE_GET_GE(&tmpa, state->pre_a + np * ECMULT_TABLE_SIZE(WINDOW_A), n, WINDOW_A);
} secp256k1_gej_add_ge_var(r, r, &tmpa, NULL);
if (i < bits_na_lam && (n = wnaf_na_lam[i])) { }
ECMULT_TABLE_GET_GE(&tmpa, pre_a_lam, n, WINDOW_A); if (i < state->ps[np].bits_na_lam && (n = state->ps[np].wnaf_na_lam[i])) {
secp256k1_gej_add_ge_var(r, r, &tmpa, NULL); ECMULT_TABLE_GET_GE(&tmpa, state->pre_a_lam + np * ECMULT_TABLE_SIZE(WINDOW_A), n, WINDOW_A);
secp256k1_gej_add_ge_var(r, r, &tmpa, NULL);
}
} }
if (i < bits_ng_1 && (n = wnaf_ng_1[i])) { if (i < bits_ng_1 && (n = wnaf_ng_1[i])) {
ECMULT_TABLE_GET_GE_STORAGE(&tmpa, *ctx->pre_g, n, WINDOW_G); ECMULT_TABLE_GET_GE_STORAGE(&tmpa, *ctx->pre_g, n, WINDOW_G);
@ -387,9 +466,11 @@ static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej
secp256k1_gej_add_zinv_var(r, r, &tmpa, &Z); secp256k1_gej_add_zinv_var(r, r, &tmpa, &Z);
} }
#else #else
if (i < bits_na && (n = wnaf_na[i])) { for (np = 0; np < no; ++np) {
ECMULT_TABLE_GET_GE(&tmpa, pre_a, n, WINDOW_A); if (i < state->ps[np].bits_na && (n = state->ps[np].wnaf_na[i])) {
secp256k1_gej_add_ge_var(r, r, &tmpa, NULL); ECMULT_TABLE_GET_GE(&tmpa, state->pre_a + np * ECMULT_TABLE_SIZE(WINDOW_A), n, WINDOW_A);
secp256k1_gej_add_ge_var(r, r, &tmpa, NULL);
}
} }
if (i < bits_ng && (n = wnaf_ng[i])) { if (i < bits_ng && (n = wnaf_ng[i])) {
ECMULT_TABLE_GET_GE_STORAGE(&tmpa, *ctx->pre_g, n, WINDOW_G); ECMULT_TABLE_GET_GE_STORAGE(&tmpa, *ctx->pre_g, n, WINDOW_G);
@ -403,4 +484,528 @@ static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej
} }
} }
static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_scalar *na, const secp256k1_scalar *ng) {
secp256k1_gej prej[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_fe zr[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_ge pre_a[ECMULT_TABLE_SIZE(WINDOW_A)];
struct secp256k1_strauss_point_state ps[1];
#ifdef USE_ENDOMORPHISM
secp256k1_ge pre_a_lam[ECMULT_TABLE_SIZE(WINDOW_A)];
#endif
struct secp256k1_strauss_state state;
state.prej = prej;
state.zr = zr;
state.pre_a = pre_a;
#ifdef USE_ENDOMORPHISM
state.pre_a_lam = pre_a_lam;
#endif
state.ps = ps;
secp256k1_ecmult_strauss_wnaf(ctx, &state, r, 1, a, na, ng);
}
static size_t secp256k1_strauss_scratch_size(size_t n_points) {
#ifdef USE_ENDOMORPHISM
static const size_t point_size = (2 * sizeof(secp256k1_ge) + sizeof(secp256k1_gej) + sizeof(secp256k1_fe)) * ECMULT_TABLE_SIZE(WINDOW_A) + sizeof(struct secp256k1_strauss_point_state) + sizeof(secp256k1_gej) + sizeof(secp256k1_scalar);
#else
static const size_t point_size = (sizeof(secp256k1_ge) + sizeof(secp256k1_gej) + sizeof(secp256k1_fe)) * ECMULT_TABLE_SIZE(WINDOW_A) + sizeof(struct secp256k1_strauss_point_state) + sizeof(secp256k1_gej) + sizeof(secp256k1_scalar);
#endif
return n_points*point_size;
}
static int secp256k1_ecmult_strauss_batch(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points, size_t cb_offset) {
secp256k1_gej* points;
secp256k1_scalar* scalars;
struct secp256k1_strauss_state state;
size_t i;
secp256k1_gej_set_infinity(r);
if (inp_g_sc == NULL && n_points == 0) {
return 1;
}
if (!secp256k1_scratch_resize(scratch, secp256k1_strauss_scratch_size(n_points), STRAUSS_SCRATCH_OBJECTS)) {
return 0;
}
secp256k1_scratch_reset(scratch);
points = (secp256k1_gej*)secp256k1_scratch_alloc(scratch, n_points * sizeof(secp256k1_gej));
scalars = (secp256k1_scalar*)secp256k1_scratch_alloc(scratch, n_points * sizeof(secp256k1_scalar));
state.prej = (secp256k1_gej*)secp256k1_scratch_alloc(scratch, n_points * ECMULT_TABLE_SIZE(WINDOW_A) * sizeof(secp256k1_gej));
state.zr = (secp256k1_fe*)secp256k1_scratch_alloc(scratch, n_points * ECMULT_TABLE_SIZE(WINDOW_A) * sizeof(secp256k1_fe));
#ifdef USE_ENDOMORPHISM
state.pre_a = (secp256k1_ge*)secp256k1_scratch_alloc(scratch, n_points * 2 * ECMULT_TABLE_SIZE(WINDOW_A) * sizeof(secp256k1_ge));
state.pre_a_lam = state.pre_a + n_points * ECMULT_TABLE_SIZE(WINDOW_A);
#else
state.pre_a = (secp256k1_ge*)secp256k1_scratch_alloc(scratch, n_points * ECMULT_TABLE_SIZE(WINDOW_A) * sizeof(secp256k1_ge));
#endif
state.ps = (struct secp256k1_strauss_point_state*)secp256k1_scratch_alloc(scratch, n_points * sizeof(struct secp256k1_strauss_point_state));
for (i = 0; i < n_points; i++) {
secp256k1_ge point;
if (!cb(&scalars[i], &point, i+cb_offset, cbdata)) return 0;
secp256k1_gej_set_ge(&points[i], &point);
}
secp256k1_ecmult_strauss_wnaf(ctx, &state, r, n_points, points, scalars, inp_g_sc);
return 1;
}
/* Wrapper for secp256k1_ecmult_multi_func interface */
static int secp256k1_ecmult_strauss_batch_single(const secp256k1_ecmult_context *actx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n) {
return secp256k1_ecmult_strauss_batch(actx, scratch, r, inp_g_sc, cb, cbdata, n, 0);
}
static size_t secp256k1_strauss_max_points(secp256k1_scratch *scratch) {
return secp256k1_scratch_max_allocation(scratch, STRAUSS_SCRATCH_OBJECTS) / secp256k1_strauss_scratch_size(1);
}
/** Convert a number to WNAF notation.
* The number becomes represented by sum(2^{wi} * wnaf[i], i=0..WNAF_SIZE(w)+1) - return_val.
* It has the following guarantees:
* - each wnaf[i] is either 0 or an odd integer between -(1 << w) and (1 << w)
* - the number of words set is always WNAF_SIZE(w)
* - the returned skew is 0 without endomorphism, or 0 or 1 with endomorphism
*/
static int secp256k1_wnaf_fixed(int *wnaf, const secp256k1_scalar *s, int w) {
int sign = 0;
int skew = 0;
int pos = 1;
#ifndef USE_ENDOMORPHISM
secp256k1_scalar neg_s;
#endif
const secp256k1_scalar *work = s;
if (secp256k1_scalar_is_zero(s)) {
while (pos * w < WNAF_BITS) {
wnaf[pos] = 0;
++pos;
}
return 0;
}
if (secp256k1_scalar_is_even(s)) {
#ifdef USE_ENDOMORPHISM
skew = 1;
#else
secp256k1_scalar_negate(&neg_s, s);
work = &neg_s;
sign = -1;
#endif
}
wnaf[0] = (secp256k1_scalar_get_bits_var(work, 0, w) + skew + sign) ^ sign;
while (pos * w < WNAF_BITS) {
int now = w;
int val;
if (now + pos * w > WNAF_BITS) {
now = WNAF_BITS - pos * w;
}
val = secp256k1_scalar_get_bits_var(work, pos * w, now);
if ((val & 1) == 0) {
wnaf[pos - 1] -= ((1 << w) + sign) ^ sign;
wnaf[pos] = (val + 1 + sign) ^ sign;
} else {
wnaf[pos] = (val + sign) ^ sign;
}
++pos;
}
VERIFY_CHECK(pos == WNAF_SIZE(w));
return skew;
}
struct secp256k1_pippenger_point_state {
int skew_na;
size_t input_pos;
};
struct secp256k1_pippenger_state {
int *wnaf_na;
struct secp256k1_pippenger_point_state* ps;
};
/*
* pippenger_wnaf computes the result of a multi-point multiplication as
* follows: The scalars are brought into wnaf with n_wnaf elements each. Then
* for every i < n_wnaf, first each point is added to a "bucket" corresponding
* to the point's wnaf[i]. Second, the buckets are added together such that
* r += 1*bucket[0] + 3*bucket[1] + 5*bucket[2] + ...
*/
static int secp256k1_ecmult_pippenger_wnaf(secp256k1_gej *buckets, int bucket_window, struct secp256k1_pippenger_state *state, secp256k1_gej *r, secp256k1_scalar *sc, secp256k1_ge *pt, size_t num) {
size_t n_wnaf = WNAF_SIZE(bucket_window+1);
size_t np;
size_t no = 0;
int i;
int j;
for (np = 0; np < num; ++np) {
if (secp256k1_scalar_is_zero(&sc[np]) || secp256k1_ge_is_infinity(&pt[np])) {
continue;
}
state->ps[no].input_pos = np;
state->ps[no].skew_na = secp256k1_wnaf_fixed(&state->wnaf_na[no*n_wnaf], &sc[np], bucket_window+1);
no++;
}
secp256k1_gej_set_infinity(r);
if (no == 0) {
return 1;
}
for (i = n_wnaf - 1; i >= 0; i--) {
secp256k1_gej running_sum;
for(j = 0; j < ECMULT_TABLE_SIZE(bucket_window+2); j++) {
secp256k1_gej_set_infinity(&buckets[j]);
}
for (np = 0; np < no; ++np) {
int n = state->wnaf_na[np*n_wnaf + i];
struct secp256k1_pippenger_point_state point_state = state->ps[np];
secp256k1_ge tmp;
int idx;
#ifdef USE_ENDOMORPHISM
if (i == 0) {
/* correct for wnaf skew */
int skew = point_state.skew_na;
if (skew) {
secp256k1_ge_neg(&tmp, &pt[point_state.input_pos]);
secp256k1_gej_add_ge_var(&buckets[0], &buckets[0], &tmp, NULL);
}
}
#endif
if (n > 0) {
idx = (n - 1)/2;
secp256k1_gej_add_ge_var(&buckets[idx], &buckets[idx], &pt[point_state.input_pos], NULL);
} else if (n < 0) {
idx = -(n + 1)/2;
secp256k1_ge_neg(&tmp, &pt[point_state.input_pos]);
secp256k1_gej_add_ge_var(&buckets[idx], &buckets[idx], &tmp, NULL);
}
}
for(j = 0; j < bucket_window; j++) {
secp256k1_gej_double_var(r, r, NULL);
}
secp256k1_gej_set_infinity(&running_sum);
/* Accumulate the sum: bucket[0] + 3*bucket[1] + 5*bucket[2] + 7*bucket[3] + ...
* = bucket[0] + bucket[1] + bucket[2] + bucket[3] + ...
* + 2 * (bucket[1] + 2*bucket[2] + 3*bucket[3] + ...)
* using an intermediate running sum:
* running_sum = bucket[0] + bucket[1] + bucket[2] + ...
*
* The doubling is done implicitly by deferring the final window doubling (of 'r').
*/
for(j = ECMULT_TABLE_SIZE(bucket_window+2) - 1; j > 0; j--) {
secp256k1_gej_add_var(&running_sum, &running_sum, &buckets[j], NULL);
secp256k1_gej_add_var(r, r, &running_sum, NULL);
}
secp256k1_gej_add_var(&running_sum, &running_sum, &buckets[0], NULL);
secp256k1_gej_double_var(r, r, NULL);
secp256k1_gej_add_var(r, r, &running_sum, NULL);
}
return 1;
}
/**
* Returns optimal bucket_window (number of bits of a scalar represented by a
* set of buckets) for a given number of points.
*/
static int secp256k1_pippenger_bucket_window(size_t n) {
#ifdef USE_ENDOMORPHISM
if (n <= 1) {
return 1;
} else if (n <= 4) {
return 2;
} else if (n <= 20) {
return 3;
} else if (n <= 57) {
return 4;
} else if (n <= 136) {
return 5;
} else if (n <= 235) {
return 6;
} else if (n <= 1260) {
return 7;
} else if (n <= 4420) {
return 9;
} else if (n <= 7880) {
return 10;
} else if (n <= 16050) {
return 11;
} else {
return PIPPENGER_MAX_BUCKET_WINDOW;
}
#else
if (n <= 1) {
return 1;
} else if (n <= 11) {
return 2;
} else if (n <= 45) {
return 3;
} else if (n <= 100) {
return 4;
} else if (n <= 275) {
return 5;
} else if (n <= 625) {
return 6;
} else if (n <= 1850) {
return 7;
} else if (n <= 3400) {
return 8;
} else if (n <= 9630) {
return 9;
} else if (n <= 17900) {
return 10;
} else if (n <= 32800) {
return 11;
} else {
return PIPPENGER_MAX_BUCKET_WINDOW;
}
#endif
}
/**
* Returns the maximum optimal number of points for a bucket_window.
*/
static size_t secp256k1_pippenger_bucket_window_inv(int bucket_window) {
switch(bucket_window) {
#ifdef USE_ENDOMORPHISM
case 1: return 1;
case 2: return 4;
case 3: return 20;
case 4: return 57;
case 5: return 136;
case 6: return 235;
case 7: return 1260;
case 8: return 1260;
case 9: return 4420;
case 10: return 7880;
case 11: return 16050;
case PIPPENGER_MAX_BUCKET_WINDOW: return SIZE_MAX;
#else
case 1: return 1;
case 2: return 11;
case 3: return 45;
case 4: return 100;
case 5: return 275;
case 6: return 625;
case 7: return 1850;
case 8: return 3400;
case 9: return 9630;
case 10: return 17900;
case 11: return 32800;
case PIPPENGER_MAX_BUCKET_WINDOW: return SIZE_MAX;
#endif
}
return 0;
}
#ifdef USE_ENDOMORPHISM
SECP256K1_INLINE static void secp256k1_ecmult_endo_split(secp256k1_scalar *s1, secp256k1_scalar *s2, secp256k1_ge *p1, secp256k1_ge *p2) {
secp256k1_scalar tmp = *s1;
secp256k1_scalar_split_lambda(s1, s2, &tmp);
secp256k1_ge_mul_lambda(p2, p1);
if (secp256k1_scalar_is_high(s1)) {
secp256k1_scalar_negate(s1, s1);
secp256k1_ge_neg(p1, p1);
}
if (secp256k1_scalar_is_high(s2)) {
secp256k1_scalar_negate(s2, s2);
secp256k1_ge_neg(p2, p2);
}
}
#endif
/**
* Returns the scratch size required for a given number of points (excluding
* base point G) without considering alignment.
*/
static size_t secp256k1_pippenger_scratch_size(size_t n_points, int bucket_window) {
#ifdef USE_ENDOMORPHISM
size_t entries = 2*n_points + 2;
#else
size_t entries = n_points + 1;
#endif
size_t entry_size = sizeof(secp256k1_ge) + sizeof(secp256k1_scalar) + sizeof(struct secp256k1_pippenger_point_state) + (WNAF_SIZE(bucket_window+1)+1)*sizeof(int);
return ((1<<bucket_window) * sizeof(secp256k1_gej) + sizeof(struct secp256k1_pippenger_state) + entries * entry_size);
}
static int secp256k1_ecmult_pippenger_batch(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n_points, size_t cb_offset) {
/* Use 2(n+1) with the endomorphism, n+1 without, when calculating batch
* sizes. The reason for +1 is that we add the G scalar to the list of
* other scalars. */
#ifdef USE_ENDOMORPHISM
size_t entries = 2*n_points + 2;
#else
size_t entries = n_points + 1;
#endif
secp256k1_ge *points;
secp256k1_scalar *scalars;
secp256k1_gej *buckets;
struct secp256k1_pippenger_state *state_space;
size_t idx = 0;
size_t point_idx = 0;
int i, j;
int bucket_window;
(void)ctx;
secp256k1_gej_set_infinity(r);
if (inp_g_sc == NULL && n_points == 0) {
return 1;
}
bucket_window = secp256k1_pippenger_bucket_window(n_points);
if (!secp256k1_scratch_resize(scratch, secp256k1_pippenger_scratch_size(n_points, bucket_window), PIPPENGER_SCRATCH_OBJECTS)) {
return 0;
}
secp256k1_scratch_reset(scratch);
points = (secp256k1_ge *) secp256k1_scratch_alloc(scratch, entries * sizeof(*points));
scalars = (secp256k1_scalar *) secp256k1_scratch_alloc(scratch, entries * sizeof(*scalars));
state_space = (struct secp256k1_pippenger_state *) secp256k1_scratch_alloc(scratch, sizeof(*state_space));
state_space->ps = (struct secp256k1_pippenger_point_state *) secp256k1_scratch_alloc(scratch, entries * sizeof(*state_space->ps));
state_space->wnaf_na = (int *) secp256k1_scratch_alloc(scratch, entries*(WNAF_SIZE(bucket_window+1)) * sizeof(int));
buckets = (secp256k1_gej *) secp256k1_scratch_alloc(scratch, (1<<bucket_window) * sizeof(*buckets));
if (inp_g_sc != NULL) {
scalars[0] = *inp_g_sc;
points[0] = secp256k1_ge_const_g;
idx++;
#ifdef USE_ENDOMORPHISM
secp256k1_ecmult_endo_split(&scalars[0], &scalars[1], &points[0], &points[1]);
idx++;
#endif
}
while (point_idx < n_points) {
if (!cb(&scalars[idx], &points[idx], point_idx + cb_offset, cbdata)) {
return 0;
}
idx++;
#ifdef USE_ENDOMORPHISM
secp256k1_ecmult_endo_split(&scalars[idx - 1], &scalars[idx], &points[idx - 1], &points[idx]);
idx++;
#endif
point_idx++;
}
secp256k1_ecmult_pippenger_wnaf(buckets, bucket_window, state_space, r, scalars, points, idx);
/* Clear data */
for(i = 0; (size_t)i < idx; i++) {
secp256k1_scalar_clear(&scalars[i]);
state_space->ps[i].skew_na = 0;
for(j = 0; j < WNAF_SIZE(bucket_window+1); j++) {
state_space->wnaf_na[i * WNAF_SIZE(bucket_window+1) + j] = 0;
}
}
for(i = 0; i < 1<<bucket_window; i++) {
secp256k1_gej_clear(&buckets[i]);
}
return 1;
}
/* Wrapper for secp256k1_ecmult_multi_func interface */
static int secp256k1_ecmult_pippenger_batch_single(const secp256k1_ecmult_context *actx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n) {
return secp256k1_ecmult_pippenger_batch(actx, scratch, r, inp_g_sc, cb, cbdata, n, 0);
}
/**
* Returns the maximum number of points in addition to G that can be used with
* a given scratch space. The function ensures that fewer points may also be
* used.
*/
static size_t secp256k1_pippenger_max_points(secp256k1_scratch *scratch) {
size_t max_alloc = secp256k1_scratch_max_allocation(scratch, PIPPENGER_SCRATCH_OBJECTS);
int bucket_window;
size_t res = 0;
for (bucket_window = 1; bucket_window <= PIPPENGER_MAX_BUCKET_WINDOW; bucket_window++) {
size_t n_points;
size_t max_points = secp256k1_pippenger_bucket_window_inv(bucket_window);
size_t space_for_points;
size_t space_overhead;
size_t entry_size = sizeof(secp256k1_ge) + sizeof(secp256k1_scalar) + sizeof(struct secp256k1_pippenger_point_state) + (WNAF_SIZE(bucket_window+1)+1)*sizeof(int);
#ifdef USE_ENDOMORPHISM
entry_size = 2*entry_size;
#endif
space_overhead = ((1<<bucket_window) * sizeof(secp256k1_gej) + entry_size + sizeof(struct secp256k1_pippenger_state));
if (space_overhead > max_alloc) {
break;
}
space_for_points = max_alloc - space_overhead;
n_points = space_for_points/entry_size;
n_points = n_points > max_points ? max_points : n_points;
if (n_points > res) {
res = n_points;
}
if (n_points < max_points) {
/* A larger bucket_window may support even more points. But if we
* would choose that then the caller couldn't safely use any number
* smaller than what this function returns */
break;
}
}
return res;
}
typedef int (*secp256k1_ecmult_multi_func)(const secp256k1_ecmult_context*, secp256k1_scratch*, secp256k1_gej*, const secp256k1_scalar*, secp256k1_ecmult_multi_callback cb, void*, size_t);
static int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n) {
size_t i;
int (*f)(const secp256k1_ecmult_context*, secp256k1_scratch*, secp256k1_gej*, const secp256k1_scalar*, secp256k1_ecmult_multi_callback cb, void*, size_t, size_t);
size_t max_points;
size_t n_batches;
size_t n_batch_points;
secp256k1_gej_set_infinity(r);
if (inp_g_sc == NULL && n == 0) {
return 1;
} else if (n == 0) {
secp256k1_scalar szero;
secp256k1_scalar_set_int(&szero, 0);
secp256k1_ecmult(ctx, r, r, &szero, inp_g_sc);
return 1;
}
max_points = secp256k1_pippenger_max_points(scratch);
if (max_points == 0) {
return 0;
} else if (max_points > ECMULT_MAX_POINTS_PER_BATCH) {
max_points = ECMULT_MAX_POINTS_PER_BATCH;
}
n_batches = (n+max_points-1)/max_points;
n_batch_points = (n+n_batches-1)/n_batches;
if (n_batch_points >= ECMULT_PIPPENGER_THRESHOLD) {
f = secp256k1_ecmult_pippenger_batch;
} else {
max_points = secp256k1_strauss_max_points(scratch);
if (max_points == 0) {
return 0;
}
n_batches = (n+max_points-1)/max_points;
n_batch_points = (n+n_batches-1)/n_batches;
f = secp256k1_ecmult_strauss_batch;
}
for(i = 0; i < n_batches; i++) {
size_t nbp = n < n_batch_points ? n : n_batch_points;
size_t offset = n_batch_points*i;
secp256k1_gej tmp;
if (!f(ctx, scratch, &tmp, i == 0 ? inp_g_sc : NULL, cb, cbdata, nbp, offset)) {
return 0;
}
secp256k1_gej_add_var(r, r, &tmp, NULL);
n -= nbp;
}
return 1;
}
#endif /* SECP256K1_ECMULT_IMPL_H */ #endif /* SECP256K1_ECMULT_IMPL_H */

3
src/group.h
View File

@ -79,6 +79,9 @@ static void secp256k1_ge_set_table_gej_var(secp256k1_ge *r, const secp256k1_gej
* stored in globalz. */ * stored in globalz. */
static void secp256k1_ge_globalz_set_table_gej(size_t len, secp256k1_ge *r, secp256k1_fe *globalz, const secp256k1_gej *a, const secp256k1_fe *zr); static void secp256k1_ge_globalz_set_table_gej(size_t len, secp256k1_ge *r, secp256k1_fe *globalz, const secp256k1_gej *a, const secp256k1_fe *zr);
/** Set a group element (affine) equal to the point at infinity. */
static void secp256k1_ge_set_infinity(secp256k1_ge *r);
/** Set a group element (jacobian) equal to the point at infinity. */ /** Set a group element (jacobian) equal to the point at infinity. */
static void secp256k1_gej_set_infinity(secp256k1_gej *r); static void secp256k1_gej_set_infinity(secp256k1_gej *r);

6
src/group_impl.h
View File

@ -200,6 +200,12 @@ static void secp256k1_gej_set_infinity(secp256k1_gej *r) {
secp256k1_fe_clear(&r->z); secp256k1_fe_clear(&r->z);
} }
static void secp256k1_ge_set_infinity(secp256k1_ge *r) {
r->infinity = 1;
secp256k1_fe_clear(&r->x);
secp256k1_fe_clear(&r->y);
}
static void secp256k1_gej_clear(secp256k1_gej *r) { static void secp256k1_gej_clear(secp256k1_gej *r) {
r->infinity = 0; r->infinity = 0;
secp256k1_fe_clear(&r->x); secp256k1_fe_clear(&r->x);

35
src/scratch.h Normal file
View File

@ -0,0 +1,35 @@
/**********************************************************************
* Copyright (c) 2017 Andrew Poelstra *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_SCRATCH_
#define _SECP256K1_SCRATCH_
/* The typedef is used internally; the struct name is used in the public API
* (where it is exposed as a different typedef) */
typedef struct secp256k1_scratch_space_struct {
void *data;
size_t offset;
size_t init_size;
size_t max_size;
const secp256k1_callback* error_callback;
} secp256k1_scratch;
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t init_size, size_t max_size);
static void secp256k1_scratch_destroy(secp256k1_scratch* scratch);
/** Returns the maximum allocation the scratch space will allow */
static size_t secp256k1_scratch_max_allocation(const secp256k1_scratch* scratch, size_t n_objects);
/** Attempts to allocate so that there are `n` available bytes. Returns 1 on success, 0 on failure */
static int secp256k1_scratch_resize(secp256k1_scratch* scratch, size_t n, size_t n_objects);
/** Returns a pointer into the scratch space or NULL if there is insufficient available space */
static void *secp256k1_scratch_alloc(secp256k1_scratch* scratch, size_t n);
/** Resets the returned pointer to the beginning of space */
static void secp256k1_scratch_reset(secp256k1_scratch* scratch);
#endif

77
src/scratch_impl.h Normal file
View File

@ -0,0 +1,77 @@
/**********************************************************************
* Copyright (c) 2017 Andrew Poelstra *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_SCRATCH_IMPL_H_
#define _SECP256K1_SCRATCH_IMPL_H_
#include "scratch.h"
/* Using 16 bytes alignment because common architectures never have alignment
* requirements above 8 for any of the types we care about. In addition we
* leave some room because currently we don't care about a few bytes.
* TODO: Determine this at configure time. */
#define ALIGNMENT 16
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t init_size, size_t max_size) {
secp256k1_scratch* ret = (secp256k1_scratch*)checked_malloc(error_callback, sizeof(*ret));
if (ret != NULL) {
ret->data = checked_malloc(error_callback, init_size);
if (ret->data == NULL) {
free (ret);
return NULL;
}
ret->offset = 0;
ret->init_size = init_size;
ret->max_size = max_size;
ret->error_callback = error_callback;
}
return ret;
}
static void secp256k1_scratch_destroy(secp256k1_scratch* scratch) {
if (scratch != NULL) {
free(scratch->data);
free(scratch);
}
}
static size_t secp256k1_scratch_max_allocation(const secp256k1_scratch* scratch, size_t objects) {
if (scratch->max_size <= objects * ALIGNMENT) {
return 0;
}
return scratch->max_size - objects * ALIGNMENT;
}
static int secp256k1_scratch_resize(secp256k1_scratch* scratch, size_t n, size_t objects) {
n += objects * ALIGNMENT;
if (n > scratch->init_size && n <= scratch->max_size) {
void *tmp = checked_realloc(scratch->error_callback, scratch->data, n);
if (tmp == NULL) {
return 0;
}
scratch->init_size = n;
scratch->data = tmp;
}
return n <= scratch->max_size;
}
static void *secp256k1_scratch_alloc(secp256k1_scratch* scratch, size_t size) {
void *ret;
size = ((size + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
if (size + scratch->offset > scratch->init_size) {
return NULL;
}
ret = (void *) ((unsigned char *) scratch->data + scratch->offset);
memset(ret, 0, size);
scratch->offset += size;
return ret;
}
static void secp256k1_scratch_reset(secp256k1_scratch* scratch) {
scratch->offset = 0;
}
#endif

12
src/secp256k1.c
View File

@ -17,6 +17,7 @@
#include "ecdsa_impl.h" #include "ecdsa_impl.h"
#include "eckey_impl.h" #include "eckey_impl.h"
#include "hash_impl.h" #include "hash_impl.h"
#include "scratch_impl.h"
#define ARG_CHECK(cond) do { \ #define ARG_CHECK(cond) do { \
if (EXPECT(!(cond), 0)) { \ if (EXPECT(!(cond), 0)) { \
@ -114,6 +115,17 @@ void secp256k1_context_set_error_callback(secp256k1_context* ctx, void (*fun)(co
ctx->error_callback.data = data; ctx->error_callback.data = data;
} }
secp256k1_scratch_space* secp256k1_scratch_space_create(const secp256k1_context* ctx, size_t init_size, size_t max_size) {
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(max_size >= init_size);
return secp256k1_scratch_create(&ctx->error_callback, init_size, max_size);
}
void secp256k1_scratch_space_destroy(secp256k1_scratch_space* scratch) {
secp256k1_scratch_destroy(scratch);
}
static int secp256k1_pubkey_load(const secp256k1_context* ctx, secp256k1_ge* ge, const secp256k1_pubkey* pubkey) { static int secp256k1_pubkey_load(const secp256k1_context* ctx, secp256k1_ge* ge, const secp256k1_pubkey* pubkey) {
if (sizeof(secp256k1_ge_storage) == 64) { if (sizeof(secp256k1_ge_storage) == 64) {
/* When the secp256k1_ge_storage type is exactly 64 byte, use its /* When the secp256k1_ge_storage type is exactly 64 byte, use its

484
src/tests.c
View File

@ -248,6 +248,41 @@ void run_context_tests(void) {
secp256k1_context_destroy(NULL); secp256k1_context_destroy(NULL);
} }
void run_scratch_tests(void) {
int32_t ecount = 0;
secp256k1_context *none = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
secp256k1_scratch_space *scratch;
/* Test public API */
secp256k1_context_set_illegal_callback(none, counting_illegal_callback_fn, &ecount);
scratch = secp256k1_scratch_space_create(none, 100, 10);
CHECK(scratch == NULL);
CHECK(ecount == 1);
scratch = secp256k1_scratch_space_create(none, 100, 100);
CHECK(scratch != NULL);
CHECK(ecount == 1);
secp256k1_scratch_space_destroy(scratch);
scratch = secp256k1_scratch_space_create(none, 100, 1000);
CHECK(scratch != NULL);
CHECK(ecount == 1);
/* Test internal API */
CHECK(secp256k1_scratch_max_allocation(scratch, 0) == 1000);
CHECK(secp256k1_scratch_max_allocation(scratch, 1) < 1000);
CHECK(secp256k1_scratch_resize(scratch, 50, 1) == 1); /* no-op */
CHECK(secp256k1_scratch_resize(scratch, 200, 1) == 1);
CHECK(secp256k1_scratch_resize(scratch, 950, 1) == 1);
CHECK(secp256k1_scratch_resize(scratch, 1000, 1) == 0);
CHECK(secp256k1_scratch_resize(scratch, 2000, 1) == 0);
CHECK(secp256k1_scratch_max_allocation(scratch, 0) == 1000);
/* cleanup */
secp256k1_scratch_space_destroy(scratch);
secp256k1_context_destroy(none);
}
/***** HASH TESTS *****/ /***** HASH TESTS *****/
void run_sha256_tests(void) { void run_sha256_tests(void) {
@ -2487,6 +2522,395 @@ void run_ecmult_const_tests(void) {
ecmult_const_chain_multiply(); ecmult_const_chain_multiply();
} }
typedef struct {
secp256k1_scalar *sc;
secp256k1_ge *pt;
} ecmult_multi_data;
static int ecmult_multi_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *cbdata) {
ecmult_multi_data *data = (ecmult_multi_data*) cbdata;
*sc = data->sc[idx];
*pt = data->pt[idx];
return 1;
}
static int ecmult_multi_false_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *cbdata) {
(void)sc;
(void)pt;
(void)idx;
(void)cbdata;
return 0;
}
void test_ecmult_multi(secp256k1_scratch *scratch, secp256k1_ecmult_multi_func ecmult_multi) {
int ncount;
secp256k1_scalar szero;
secp256k1_scalar sc[32];
secp256k1_ge pt[32];
secp256k1_gej r;
secp256k1_gej r2;
ecmult_multi_data data;
secp256k1_scratch *scratch_empty;
data.sc = sc;
data.pt = pt;
secp256k1_scalar_set_int(&szero, 0);
secp256k1_scratch_reset(scratch);
/* No points to multiply */
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, NULL, ecmult_multi_callback, &data, 0));
/* Check 1- and 2-point multiplies against ecmult */
for (ncount = 0; ncount < count; ncount++) {
secp256k1_ge ptg;
secp256k1_gej ptgj;
random_scalar_order(&sc[0]);
random_scalar_order(&sc[1]);
random_group_element_test(&ptg);
secp256k1_gej_set_ge(&ptgj, &ptg);
pt[0] = ptg;
pt[1] = secp256k1_ge_const_g;
/* only G scalar */
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &ptgj, &szero, &sc[0]);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &sc[0], ecmult_multi_callback, &data, 0));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
/* 1-point */
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &ptgj, &sc[0], &szero);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 1));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
/* Try to multiply 1 point, but scratch space is empty */
scratch_empty = secp256k1_scratch_create(&ctx->error_callback, 0, 0);
CHECK(!ecmult_multi(&ctx->ecmult_ctx, scratch_empty, &r, &szero, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch_empty);
/* Try to multiply 1 point, but callback returns false */
CHECK(!ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_false_callback, &data, 1));
/* 2-point */
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &ptgj, &sc[0], &sc[1]);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 2));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
/* 2-point with G scalar */
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &ptgj, &sc[0], &sc[1]);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &sc[1], ecmult_multi_callback, &data, 1));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
}
/* Check infinite outputs of various forms */
for (ncount = 0; ncount < count; ncount++) {
secp256k1_ge ptg;
size_t i, j;
size_t sizes[] = { 2, 10, 32 };
for (j = 0; j < 3; j++) {
for (i = 0; i < 32; i++) {
random_scalar_order(&sc[i]);
secp256k1_ge_set_infinity(&pt[i]);
}
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, sizes[j]));
CHECK(secp256k1_gej_is_infinity(&r));
}
for (j = 0; j < 3; j++) {
for (i = 0; i < 32; i++) {
random_group_element_test(&ptg);
pt[i] = ptg;
secp256k1_scalar_set_int(&sc[i], 0);
}
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, sizes[j]));
CHECK(secp256k1_gej_is_infinity(&r));
}
for (j = 0; j < 3; j++) {
random_group_element_test(&ptg);
for (i = 0; i < 16; i++) {
random_scalar_order(&sc[2*i]);
secp256k1_scalar_negate(&sc[2*i + 1], &sc[2*i]);
pt[2 * i] = ptg;
pt[2 * i + 1] = ptg;
}
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, sizes[j]));
CHECK(secp256k1_gej_is_infinity(&r));
random_scalar_order(&sc[0]);
for (i = 0; i < 16; i++) {
random_group_element_test(&ptg);
sc[2*i] = sc[0];
sc[2*i+1] = sc[0];
pt[2 * i] = ptg;
secp256k1_ge_neg(&pt[2*i+1], &pt[2*i]);
}
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, sizes[j]));
CHECK(secp256k1_gej_is_infinity(&r));
}
random_group_element_test(&ptg);
secp256k1_scalar_set_int(&sc[0], 0);
pt[0] = ptg;
for (i = 1; i < 32; i++) {
pt[i] = ptg;
random_scalar_order(&sc[i]);
secp256k1_scalar_add(&sc[0], &sc[0], &sc[i]);
secp256k1_scalar_negate(&sc[i], &sc[i]);
}
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 32));
CHECK(secp256k1_gej_is_infinity(&r));
}
/* Check random points, constant scalar */
for (ncount = 0; ncount < count; ncount++) {
size_t i;
secp256k1_gej_set_infinity(&r);
random_scalar_order(&sc[0]);
for (i = 0; i < 20; i++) {
secp256k1_ge ptg;
sc[i] = sc[0];
random_group_element_test(&ptg);
pt[i] = ptg;
secp256k1_gej_add_ge_var(&r, &r, &pt[i], NULL);
}
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &r, &sc[0], &szero);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 20));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
}
/* Check random scalars, constant point */
for (ncount = 0; ncount < count; ncount++) {
size_t i;
secp256k1_ge ptg;
secp256k1_gej p0j;
secp256k1_scalar rs;
secp256k1_scalar_set_int(&rs, 0);
random_group_element_test(&ptg);
for (i = 0; i < 20; i++) {
random_scalar_order(&sc[i]);
pt[i] = ptg;
secp256k1_scalar_add(&rs, &rs, &sc[i]);
}
secp256k1_gej_set_ge(&p0j, &pt[0]);
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &p0j, &rs, &szero);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 20));
secp256k1_gej_neg(&r2, &r2);
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
}
/* Sanity check that zero scalars don't cause problems */
secp256k1_scalar_clear(&sc[0]);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 20));
secp256k1_scalar_clear(&sc[1]);
secp256k1_scalar_clear(&sc[2]);
secp256k1_scalar_clear(&sc[3]);
secp256k1_scalar_clear(&sc[4]);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 6));
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &r, &szero, ecmult_multi_callback, &data, 5));
CHECK(secp256k1_gej_is_infinity(&r));
/* Run through s0*(t0*P) + s1*(t1*P) exhaustively for many small values of s0, s1, t0, t1 */
{
const size_t TOP = 8;
size_t s0i, s1i;
size_t t0i, t1i;
secp256k1_ge ptg;
secp256k1_gej ptgj;
random_group_element_test(&ptg);
secp256k1_gej_set_ge(&ptgj, &ptg);
for(t0i = 0; t0i < TOP; t0i++) {
for(t1i = 0; t1i < TOP; t1i++) {
secp256k1_gej t0p, t1p;
secp256k1_scalar t0, t1;
secp256k1_scalar_set_int(&t0, (t0i + 1) / 2);
secp256k1_scalar_cond_negate(&t0, t0i & 1);
secp256k1_scalar_set_int(&t1, (t1i + 1) / 2);
secp256k1_scalar_cond_negate(&t1, t1i & 1);
secp256k1_ecmult(&ctx->ecmult_ctx, &t0p, &ptgj, &t0, &szero);
secp256k1_ecmult(&ctx->ecmult_ctx, &t1p, &ptgj, &t1, &szero);
for(s0i = 0; s0i < TOP; s0i++) {
for(s1i = 0; s1i < TOP; s1i++) {
secp256k1_scalar tmp1, tmp2;
secp256k1_gej expected, actual;
secp256k1_ge_set_gej(&pt[0], &t0p);
secp256k1_ge_set_gej(&pt[1], &t1p);
secp256k1_scalar_set_int(&sc[0], (s0i + 1) / 2);
secp256k1_scalar_cond_negate(&sc[0], s0i & 1);
secp256k1_scalar_set_int(&sc[1], (s1i + 1) / 2);
secp256k1_scalar_cond_negate(&sc[1], s1i & 1);
secp256k1_scalar_mul(&tmp1, &t0, &sc[0]);
secp256k1_scalar_mul(&tmp2, &t1, &sc[1]);
secp256k1_scalar_add(&tmp1, &tmp1, &tmp2);
secp256k1_ecmult(&ctx->ecmult_ctx, &expected, &ptgj, &tmp1, &szero);
CHECK(ecmult_multi(&ctx->ecmult_ctx, scratch, &actual, &szero, ecmult_multi_callback, &data, 2));
secp256k1_gej_neg(&expected, &expected);
secp256k1_gej_add_var(&actual, &actual, &expected, NULL);
CHECK(secp256k1_gej_is_infinity(&actual));
}
}
}
}
}
}
void test_secp256k1_pippenger_bucket_window_inv(void) {
int i;
CHECK(secp256k1_pippenger_bucket_window_inv(0) == 0);
for(i = 1; i <= PIPPENGER_MAX_BUCKET_WINDOW; i++) {
#ifdef USE_ENDOMORPHISM
/* Bucket_window of 8 is not used with endo */
if (i == 8) {
continue;
}
#endif
CHECK(secp256k1_pippenger_bucket_window(secp256k1_pippenger_bucket_window_inv(i)) == i);
if (i != PIPPENGER_MAX_BUCKET_WINDOW) {
CHECK(secp256k1_pippenger_bucket_window(secp256k1_pippenger_bucket_window_inv(i)+1) > i);
}
}
}
/**
* Probabilistically test the function returning the maximum number of possible points
* for a given scratch space.
*/
void test_ecmult_multi_pippenger_max_points(void) {
size_t scratch_size = secp256k1_rand_int(256);
size_t max_size = secp256k1_pippenger_scratch_size(secp256k1_pippenger_bucket_window_inv(PIPPENGER_MAX_BUCKET_WINDOW-1)+512, 12);
secp256k1_scratch *scratch;
size_t n_points_supported;
int bucket_window = 0;
for(; scratch_size < max_size; scratch_size+=256) {
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size);
CHECK(scratch != NULL);
n_points_supported = secp256k1_pippenger_max_points(scratch);
if (n_points_supported == 0) {
secp256k1_scratch_destroy(scratch);
continue;
}
bucket_window = secp256k1_pippenger_bucket_window(n_points_supported);
CHECK(secp256k1_scratch_resize(scratch, secp256k1_pippenger_scratch_size(n_points_supported, bucket_window), PIPPENGER_SCRATCH_OBJECTS));
secp256k1_scratch_destroy(scratch);
}
CHECK(bucket_window == PIPPENGER_MAX_BUCKET_WINDOW);
}
/**
* Run secp256k1_ecmult_multi_var with num points and a scratch space restricted to
* 1 <= i <= num points.
*/
void test_ecmult_multi_batching(void) {
static const int n_points = 2*ECMULT_PIPPENGER_THRESHOLD;
secp256k1_scalar scG;
secp256k1_scalar szero;
secp256k1_scalar *sc = (secp256k1_scalar *)checked_malloc(&ctx->error_callback, sizeof(secp256k1_scalar) * n_points);
secp256k1_ge *pt = (secp256k1_ge *)checked_malloc(&ctx->error_callback, sizeof(secp256k1_ge) * n_points);
secp256k1_gej r;
secp256k1_gej r2;
ecmult_multi_data data;
int i;
secp256k1_scratch *scratch;
secp256k1_gej_set_infinity(&r2);
secp256k1_scalar_set_int(&szero, 0);
/* Get random scalars and group elements and compute result */
random_scalar_order(&scG);
secp256k1_ecmult(&ctx->ecmult_ctx, &r2, &r2, &szero, &scG);
for(i = 0; i < n_points; i++) {
secp256k1_ge ptg;
secp256k1_gej ptgj;
random_group_element_test(&ptg);
secp256k1_gej_set_ge(&ptgj, &ptg);
pt[i] = ptg;
random_scalar_order(&sc[i]);
secp256k1_ecmult(&ctx->ecmult_ctx, &ptgj, &ptgj, &sc[i], NULL);
secp256k1_gej_add_var(&r2, &r2, &ptgj, NULL);
}
data.sc = sc;
data.pt = pt;
/* Test with empty scratch space */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, 0);
CHECK(!secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch);
/* Test with space for 1 point in pippenger. That's not enough because
* ecmult_multi selects strauss which requires more memory. */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, secp256k1_pippenger_scratch_size(1, 1) + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
CHECK(!secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, 1));
secp256k1_scratch_destroy(scratch);
secp256k1_gej_neg(&r2, &r2);
for(i = 1; i <= n_points; i++) {
if (i > ECMULT_PIPPENGER_THRESHOLD) {
int bucket_window = secp256k1_pippenger_bucket_window(i);
size_t scratch_size = secp256k1_pippenger_scratch_size(i, bucket_window);
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size + PIPPENGER_SCRATCH_OBJECTS*ALIGNMENT);
} else {
size_t scratch_size = secp256k1_strauss_scratch_size(i);
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, scratch_size + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
}
CHECK(secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &r, &scG, ecmult_multi_callback, &data, n_points));
secp256k1_gej_add_var(&r, &r, &r2, NULL);
CHECK(secp256k1_gej_is_infinity(&r));
secp256k1_scratch_destroy(scratch);
}
free(sc);
free(pt);
}
void run_ecmult_multi_tests(void) {
secp256k1_scratch *scratch;
test_secp256k1_pippenger_bucket_window_inv();
test_ecmult_multi_pippenger_max_points();
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, 819200);
test_ecmult_multi(scratch, secp256k1_ecmult_multi_var);
test_ecmult_multi(scratch, secp256k1_ecmult_pippenger_batch_single);
test_ecmult_multi(scratch, secp256k1_ecmult_strauss_batch_single);
secp256k1_scratch_destroy(scratch);
/* Run test_ecmult_multi with space for exactly one point */
scratch = secp256k1_scratch_create(&ctx->error_callback, 0, secp256k1_strauss_scratch_size(1) + STRAUSS_SCRATCH_OBJECTS*ALIGNMENT);
test_ecmult_multi(scratch, secp256k1_ecmult_multi_var);
secp256k1_scratch_destroy(scratch);
test_ecmult_multi_batching();
}
void test_wnaf(const secp256k1_scalar *number, int w) { void test_wnaf(const secp256k1_scalar *number, int w) {
secp256k1_scalar x, two, t; secp256k1_scalar x, two, t;
int wnaf[256]; int wnaf[256];
@ -2575,6 +2999,61 @@ void test_constant_wnaf(const secp256k1_scalar *number, int w) {
CHECK(secp256k1_scalar_eq(&x, &num)); CHECK(secp256k1_scalar_eq(&x, &num));
} }
void test_fixed_wnaf(const secp256k1_scalar *number, int w) {
secp256k1_scalar x, shift;
int wnaf[256] = {0};
int i;
int skew;
secp256k1_scalar num = *number;
secp256k1_scalar_set_int(&x, 0);
secp256k1_scalar_set_int(&shift, 1 << w);
/* With USE_ENDOMORPHISM on we only consider 128-bit numbers */
#ifdef USE_ENDOMORPHISM
for (i = 0; i < 16; ++i) {
secp256k1_scalar_shr_int(&num, 8);
}
#endif
skew = secp256k1_wnaf_fixed(wnaf, &num, w);
for (i = WNAF_SIZE(w)-1; i >= 0; --i) {
secp256k1_scalar t;
int v = wnaf[i];
CHECK(v != 0); /* check nonzero */
CHECK(v & 1); /* check parity */
CHECK(v > -(1 << w)); /* check range above */
CHECK(v < (1 << w)); /* check range below */
secp256k1_scalar_mul(&x, &x, &shift);
if (v >= 0) {
secp256k1_scalar_set_int(&t, v);
} else {
secp256k1_scalar_set_int(&t, -v);
secp256k1_scalar_negate(&t, &t);
}
secp256k1_scalar_add(&x, &x, &t);
}
/* If skew is 1 then add 1 to num */
secp256k1_scalar_cadd_bit(&num, 0, skew == 1);
CHECK(secp256k1_scalar_eq(&x, &num));
}
void test_fixed_wnaf_zero(int w) {
int wnaf[256] = {0};
int i;
int skew;
secp256k1_scalar num;
secp256k1_scalar_set_int(&num, 0);
skew = secp256k1_wnaf_fixed(wnaf, &num, w);
for (i = WNAF_SIZE(w)-1; i >= 0; --i) {
int v = wnaf[i];
CHECK(v == 0);
}
CHECK(skew == 0);
}
void run_wnaf(void) { void run_wnaf(void) {
int i; int i;
secp256k1_scalar n = {{0}}; secp256k1_scalar n = {{0}};
@ -2585,12 +3064,15 @@ void run_wnaf(void) {
test_constant_wnaf(&n, 4); test_constant_wnaf(&n, 4);
n.d[0] = 2; n.d[0] = 2;
test_constant_wnaf(&n, 4); test_constant_wnaf(&n, 4);
/* Test 0 */
test_fixed_wnaf_zero(4);
/* Random tests */ /* Random tests */
for (i = 0; i < count; i++) { for (i = 0; i < count; i++) {
random_scalar_order(&n); random_scalar_order(&n);
test_wnaf(&n, 4+(i%10)); test_wnaf(&n, 4+(i%10));
test_constant_wnaf_negate(&n); test_constant_wnaf_negate(&n);
test_constant_wnaf(&n, 4 + (i % 10)); test_constant_wnaf(&n, 4 + (i % 10));
test_fixed_wnaf(&n, 4 + (i % 10));
} }
secp256k1_scalar_set_int(&n, 0); secp256k1_scalar_set_int(&n, 0);
CHECK(secp256k1_scalar_cond_negate(&n, 1) == -1); CHECK(secp256k1_scalar_cond_negate(&n, 1) == -1);
@ -4451,6 +4933,7 @@ int main(int argc, char **argv) {
/* initialize */ /* initialize */
run_context_tests(); run_context_tests();
run_scratch_tests();
ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
if (secp256k1_rand_bits(1)) { if (secp256k1_rand_bits(1)) {
secp256k1_rand256(run32); secp256k1_rand256(run32);
@ -4492,6 +4975,7 @@ int main(int argc, char **argv) {
run_ecmult_constants(); run_ecmult_constants();
run_ecmult_gen_blind(); run_ecmult_gen_blind();
run_ecmult_const_tests(); run_ecmult_const_tests();
run_ecmult_multi_tests();
run_ec_combine(); run_ec_combine();
/* endomorphism tests */ /* endomorphism tests */

41
src/tests_exhaustive.c
View File

@ -182,6 +182,46 @@ void test_exhaustive_ecmult(const secp256k1_context *ctx, const secp256k1_ge *gr
} }
} }
typedef struct {
secp256k1_scalar sc[2];
secp256k1_ge pt[2];
} ecmult_multi_data;
static int ecmult_multi_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *cbdata) {
ecmult_multi_data *data = (ecmult_multi_data*) cbdata;
*sc = data->sc[idx];
*pt = data->pt[idx];
return 1;
}
void test_exhaustive_ecmult_multi(const secp256k1_context *ctx, const secp256k1_ge *group, int order) {
int i, j, k, x, y;
secp256k1_scratch *scratch = secp256k1_scratch_create(&ctx->error_callback, 1024, 4096);
for (i = 0; i < order; i++) {
for (j = 0; j < order; j++) {
for (k = 0; k < order; k++) {
for (x = 0; x < order; x++) {
for (y = 0; y < order; y++) {
secp256k1_gej tmp;
secp256k1_scalar g_sc;
ecmult_multi_data data;
secp256k1_scalar_set_int(&data.sc[0], i);
secp256k1_scalar_set_int(&data.sc[1], j);
secp256k1_scalar_set_int(&g_sc, k);
data.pt[0] = group[x];
data.pt[1] = group[y];
secp256k1_ecmult_multi_var(&ctx->ecmult_ctx, scratch, &tmp, &g_sc, ecmult_multi_callback, &data, 2);
ge_equals_gej(&group[(i * x + j * y + k) % order], &tmp);
}
}
}
}
}
secp256k1_scratch_destroy(scratch);
}
void r_from_k(secp256k1_scalar *r, const secp256k1_ge *group, int k) { void r_from_k(secp256k1_scalar *r, const secp256k1_ge *group, int k) {
secp256k1_fe x; secp256k1_fe x;
unsigned char x_bin[32]; unsigned char x_bin[32];
@ -456,6 +496,7 @@ int main(void) {
#endif #endif
test_exhaustive_addition(group, groupj, EXHAUSTIVE_TEST_ORDER); test_exhaustive_addition(group, groupj, EXHAUSTIVE_TEST_ORDER);
test_exhaustive_ecmult(ctx, group, groupj, EXHAUSTIVE_TEST_ORDER); test_exhaustive_ecmult(ctx, group, groupj, EXHAUSTIVE_TEST_ORDER);
test_exhaustive_ecmult_multi(ctx, group, EXHAUSTIVE_TEST_ORDER);
test_exhaustive_sign(ctx, group, EXHAUSTIVE_TEST_ORDER); test_exhaustive_sign(ctx, group, EXHAUSTIVE_TEST_ORDER);
test_exhaustive_verify(ctx, group, EXHAUSTIVE_TEST_ORDER); test_exhaustive_verify(ctx, group, EXHAUSTIVE_TEST_ORDER);

8
src/util.h
View File

@ -76,6 +76,14 @@ static SECP256K1_INLINE void *checked_malloc(const secp256k1_callback* cb, size_
return ret; return ret;
} }
static SECP256K1_INLINE void *checked_realloc(const secp256k1_callback* cb, void *ptr, size_t size) {
void *ret = realloc(ptr, size);
if (ret == NULL) {
secp256k1_callback_call(cb, "Out of memory");
}
return ret;
}
/* Macro for restrict, when available and not in a VERIFY build. */ /* Macro for restrict, when available and not in a VERIFY build. */
#if defined(SECP256K1_BUILD) && defined(VERIFY) #if defined(SECP256K1_BUILD) && defined(VERIFY)
# define SECP256K1_RESTRICT # define SECP256K1_RESTRICT