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Add ability to use a statically generated ecmult context.

This vastly shrinks the size of the context required for signing on devices with
memory-mapped Flash.

Tables are generated by the new gen_context tool into a header.
master
Thomas Daede 8 years ago
parent
commit
fbecc38a89
  1. 2
      .gitignore
  2. 18
      Makefile.am
  3. 125
      build-aux/m4/ax_prog_cc_for_build.m4
  4. 11
      configure.ac
  5. 32
      src/basic-config.h
  6. 17
      src/ecmult_gen_impl.h
  7. 2
      src/field_10x26.h
  8. 63
      src/gen_context.c
  9. 2
      src/group.h

2
.gitignore vendored

@ -4,6 +4,7 @@ bench_verify @@ -4,6 +4,7 @@ bench_verify
bench_recover
bench_internal
tests
gen_context
*.exe
*.so
*.a
@ -28,6 +29,7 @@ build-aux/ @@ -28,6 +29,7 @@ build-aux/
*~
src/libsecp256k1-config.h
src/libsecp256k1-config.h.in
src/ecmult_static_context.h
m4/libtool.m4
m4/ltoptions.m4
m4/ltsugar.m4

18
Makefile.am

@ -74,4 +74,22 @@ tests_LDFLAGS = -static @@ -74,4 +74,22 @@ tests_LDFLAGS = -static
TESTS = tests
endif
if USE_ECMULT_STATIC_PRECOMPUTATION
CPPFLAGS_FOR_BUILD +=-I.
CFLAGS_FOR_BUILD += -Wall -Wextra -Wno-unused-function
gen_context_OBJECTS = gen_context.o
gen_%.o: src/gen_%.c
$(CC_FOR_BUILD) $(CPPFLAGS_FOR_BUILD) $(CFLAGS_FOR_BUILD) -c $< -o $@
gen_context$(BUILD_EXEEXT): $(gen_context_OBJECTS)
$(CC_FOR_BUILD) $^ -o $@
BUILT_SOURCES = src/ecmult_static_context.h
src/ecmult_static_context.h: gen_context
./gen_context
endif
EXTRA_DIST = autogen.sh

125
build-aux/m4/ax_prog_cc_for_build.m4

@ -0,0 +1,125 @@ @@ -0,0 +1,125 @@
# ===========================================================================
# http://www.gnu.org/software/autoconf-archive/ax_prog_cc_for_build.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_PROG_CC_FOR_BUILD
#
# DESCRIPTION
#
# This macro searches for a C compiler that generates native executables,
# that is a C compiler that surely is not a cross-compiler. This can be
# useful if you have to generate source code at compile-time like for
# example GCC does.
#
# The macro sets the CC_FOR_BUILD and CPP_FOR_BUILD macros to anything
# needed to compile or link (CC_FOR_BUILD) and preprocess (CPP_FOR_BUILD).
# The value of these variables can be overridden by the user by specifying
# a compiler with an environment variable (like you do for standard CC).
#
# It also sets BUILD_EXEEXT and BUILD_OBJEXT to the executable and object
# file extensions for the build platform, and GCC_FOR_BUILD to `yes' if
# the compiler we found is GCC. All these variables but GCC_FOR_BUILD are
# substituted in the Makefile.
#
# LICENSE
#
# Copyright (c) 2008 Paolo Bonzini <bonzini@gnu.org>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 8
AU_ALIAS([AC_PROG_CC_FOR_BUILD], [AX_PROG_CC_FOR_BUILD])
AC_DEFUN([AX_PROG_CC_FOR_BUILD], [dnl
AC_REQUIRE([AC_PROG_CC])dnl
AC_REQUIRE([AC_PROG_CPP])dnl
AC_REQUIRE([AC_EXEEXT])dnl
AC_REQUIRE([AC_CANONICAL_HOST])dnl
dnl Use the standard macros, but make them use other variable names
dnl
pushdef([ac_cv_prog_CPP], ac_cv_build_prog_CPP)dnl
pushdef([ac_cv_prog_gcc], ac_cv_build_prog_gcc)dnl
pushdef([ac_cv_prog_cc_works], ac_cv_build_prog_cc_works)dnl
pushdef([ac_cv_prog_cc_cross], ac_cv_build_prog_cc_cross)dnl
pushdef([ac_cv_prog_cc_g], ac_cv_build_prog_cc_g)dnl
pushdef([ac_cv_exeext], ac_cv_build_exeext)dnl
pushdef([ac_cv_objext], ac_cv_build_objext)dnl
pushdef([ac_exeext], ac_build_exeext)dnl
pushdef([ac_objext], ac_build_objext)dnl
pushdef([CC], CC_FOR_BUILD)dnl
pushdef([CPP], CPP_FOR_BUILD)dnl
pushdef([CFLAGS], CFLAGS_FOR_BUILD)dnl
pushdef([CPPFLAGS], CPPFLAGS_FOR_BUILD)dnl
pushdef([LDFLAGS], LDFLAGS_FOR_BUILD)dnl
pushdef([host], build)dnl
pushdef([host_alias], build_alias)dnl
pushdef([host_cpu], build_cpu)dnl
pushdef([host_vendor], build_vendor)dnl
pushdef([host_os], build_os)dnl
pushdef([ac_cv_host], ac_cv_build)dnl
pushdef([ac_cv_host_alias], ac_cv_build_alias)dnl
pushdef([ac_cv_host_cpu], ac_cv_build_cpu)dnl
pushdef([ac_cv_host_vendor], ac_cv_build_vendor)dnl
pushdef([ac_cv_host_os], ac_cv_build_os)dnl
pushdef([ac_cpp], ac_build_cpp)dnl
pushdef([ac_compile], ac_build_compile)dnl
pushdef([ac_link], ac_build_link)dnl
save_cross_compiling=$cross_compiling
save_ac_tool_prefix=$ac_tool_prefix
cross_compiling=no
ac_tool_prefix=
AC_PROG_CC
AC_PROG_CPP
AC_EXEEXT
ac_tool_prefix=$save_ac_tool_prefix
cross_compiling=$save_cross_compiling
dnl Restore the old definitions
dnl
popdef([ac_link])dnl
popdef([ac_compile])dnl
popdef([ac_cpp])dnl
popdef([ac_cv_host_os])dnl
popdef([ac_cv_host_vendor])dnl
popdef([ac_cv_host_cpu])dnl
popdef([ac_cv_host_alias])dnl
popdef([ac_cv_host])dnl
popdef([host_os])dnl
popdef([host_vendor])dnl
popdef([host_cpu])dnl
popdef([host_alias])dnl
popdef([host])dnl
popdef([LDFLAGS])dnl
popdef([CPPFLAGS])dnl
popdef([CFLAGS])dnl
popdef([CPP])dnl
popdef([CC])dnl
popdef([ac_objext])dnl
popdef([ac_exeext])dnl
popdef([ac_cv_objext])dnl
popdef([ac_cv_exeext])dnl
popdef([ac_cv_prog_cc_g])dnl
popdef([ac_cv_prog_cc_cross])dnl
popdef([ac_cv_prog_cc_works])dnl
popdef([ac_cv_prog_gcc])dnl
popdef([ac_cv_prog_CPP])dnl
dnl Finally, set Makefile variables
dnl
BUILD_EXEEXT=$ac_build_exeext
BUILD_OBJEXT=$ac_build_objext
AC_SUBST(BUILD_EXEEXT)dnl
AC_SUBST(BUILD_OBJEXT)dnl
AC_SUBST([CFLAGS_FOR_BUILD])dnl
AC_SUBST([CPPFLAGS_FOR_BUILD])dnl
AC_SUBST([LDFLAGS_FOR_BUILD])dnl
])

11
configure.ac

@ -17,6 +17,7 @@ PKG_PROG_PKG_CONFIG @@ -17,6 +17,7 @@ PKG_PROG_PKG_CONFIG
AC_PATH_TOOL(AR, ar)
AC_PATH_TOOL(RANLIB, ranlib)
AC_PATH_TOOL(STRIP, strip)
AX_PROG_CC_FOR_BUILD
if test "x$CFLAGS" = "x"; then
CFLAGS="-O3 -g"
@ -95,6 +96,11 @@ AC_ARG_ENABLE(endomorphism, @@ -95,6 +96,11 @@ AC_ARG_ENABLE(endomorphism,
AS_HELP_STRING([--enable-endomorphism],[enable endomorphism (default is no)]),
[use_endomorphism=$enableval],
[use_endomorphism=no])
AC_ARG_ENABLE(ecmult_static_precomputation,
AS_HELP_STRING([--enable-ecmult-static-precomputation],[enable precomputed ecmult table for signing (default is no)]),
[use_ecmult_static_precomputation=$enableval],
[use_ecmult_static_precomputation=no])
AC_ARG_WITH([field], [AS_HELP_STRING([--with-field=64bit|32bit|auto],
[Specify Field Implementation. Default is auto])],[req_field=$withval], [req_field=auto])
@ -305,6 +311,10 @@ if test x"$use_endomorphism" = x"yes"; then @@ -305,6 +311,10 @@ if test x"$use_endomorphism" = x"yes"; then
AC_DEFINE(USE_ENDOMORPHISM, 1, [Define this symbol to use endomorphism optimization])
fi
if test x"$use_ecmult_static_precomputation" = x"yes"; then
AC_DEFINE(USE_ECMULT_STATIC_PRECOMPUTATION, 1, [Define this symbol to use a statically generated ecmult table])
fi
AC_C_BIGENDIAN()
AC_MSG_NOTICE([Using assembly optimizations: $set_asm])
@ -321,6 +331,7 @@ AC_SUBST(SECP_TEST_LIBS) @@ -321,6 +331,7 @@ AC_SUBST(SECP_TEST_LIBS)
AC_SUBST(SECP_TEST_INCLUDES)
AM_CONDITIONAL([USE_TESTS], [test x"$use_tests" != x"no"])
AM_CONDITIONAL([USE_BENCHMARK], [test x"$use_benchmark" = x"yes"])
AM_CONDITIONAL([USE_ECMULT_STATIC_PRECOMPUTATION], [test x"$use_ecmult_static_precomputation" = x"yes"])
dnl make sure nothing new is exported so that we don't break the cache
PKGCONFIG_PATH_TEMP="$PKG_CONFIG_PATH"

32
src/basic-config.h

@ -0,0 +1,32 @@ @@ -0,0 +1,32 @@
/**********************************************************************
* Copyright (c) 2013, 2014 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_BASIC_CONFIG_
#define _SECP256K1_BASIC_CONFIG_
#ifdef USE_BASIC_CONFIG
#undef USE_ASM_X86_64
#undef USE_ENDOMORPHISM
#undef USE_FIELD_10X26
#undef USE_FIELD_5X52
#undef USE_FIELD_INV_BUILTIN
#undef USE_FIELD_INV_NUM
#undef USE_NUM_GMP
#undef USE_NUM_NONE
#undef USE_SCALAR_4X64
#undef USE_SCALAR_8X32
#undef USE_SCALAR_INV_BUILTIN
#undef USE_SCALAR_INV_NUM
#define USE_NUM_NONE 1
#define USE_FIELD_INV_BUILTIN 1
#define USE_SCALAR_INV_BUILTIN 1
#define USE_FIELD_10X26 1
#define USE_SCALAR_8X32 1
#endif // USE_BASIC_CONFIG
#endif // _SECP256K1_BASIC_CONFIG_

17
src/ecmult_gen_impl.h

@ -11,21 +11,25 @@ @@ -11,21 +11,25 @@
#include "group.h"
#include "ecmult_gen.h"
#include "hash_impl.h"
#ifdef USE_ECMULT_STATIC_PRECOMPUTATION
#include "ecmult_static_context.h"
#endif
static void secp256k1_ecmult_gen_context_init(secp256k1_ecmult_gen_context_t *ctx) {
ctx->prec = NULL;
}
static void secp256k1_ecmult_gen_context_build(secp256k1_ecmult_gen_context_t *ctx) {
#ifndef USE_ECMULT_STATIC_PRECOMPUTATION
secp256k1_ge_t prec[1024];
secp256k1_gej_t gj;
secp256k1_gej_t nums_gej;
int i, j;
#endif
if (ctx->prec != NULL) {
return;
}
#ifndef USE_ECMULT_STATIC_PRECOMPUTATION
ctx->prec = (secp256k1_ge_storage_t (*)[64][16])checked_malloc(sizeof(*ctx->prec));
/* get the generator */
@ -75,6 +79,9 @@ static void secp256k1_ecmult_gen_context_build(secp256k1_ecmult_gen_context_t *c @@ -75,6 +79,9 @@ static void secp256k1_ecmult_gen_context_build(secp256k1_ecmult_gen_context_t *c
secp256k1_ge_to_storage(&(*ctx->prec)[j][i], &prec[j*16 + i]);
}
}
#else
ctx->prec = (secp256k1_ge_storage_t (*)[64][16])secp256k1_ecmult_static_context;
#endif
secp256k1_ecmult_gen_blind(ctx, NULL);
}
@ -87,15 +94,21 @@ static void secp256k1_ecmult_gen_context_clone(secp256k1_ecmult_gen_context_t *d @@ -87,15 +94,21 @@ static void secp256k1_ecmult_gen_context_clone(secp256k1_ecmult_gen_context_t *d
if (src->prec == NULL) {
dst->prec = NULL;
} else {
#ifndef USE_ECMULT_STATIC_PRECOMPUTATION
dst->prec = (secp256k1_ge_storage_t (*)[64][16])checked_malloc(sizeof(*dst->prec));
memcpy(dst->prec, src->prec, sizeof(*dst->prec));
#else
dst->prec = src->prec;
#endif
dst->initial = src->initial;
dst->blind = src->blind;
}
}
static void secp256k1_ecmult_gen_context_clear(secp256k1_ecmult_gen_context_t *ctx) {
#ifndef USE_ECMULT_STATIC_PRECOMPUTATION
free(ctx->prec);
#endif
secp256k1_scalar_clear(&ctx->blind);
secp256k1_gej_clear(&ctx->initial);
ctx->prec = NULL;

2
src/field_10x26.h

@ -43,5 +43,5 @@ typedef struct { @@ -43,5 +43,5 @@ typedef struct {
} secp256k1_fe_storage_t;
#define SECP256K1_FE_STORAGE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {{ (d0), (d1), (d2), (d3), (d4), (d5), (d6), (d7) }}
#define SECP256K1_FE_STORAGE_CONST_GET(d) d.n[7], d.n[6], d.n[5], d.n[4],d.n[3], d.n[2], d.n[1], d.n[0]
#endif

63
src/gen_context.c

@ -0,0 +1,63 @@ @@ -0,0 +1,63 @@
/**********************************************************************
* Copyright (c) 2013, 2014, 2015 Thomas Daede, Cory Fields *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#define USE_BASIC_CONFIG 1
#include "basic-config.h"
#include "include/secp256k1.h"
#include "field_impl.h"
#include "scalar_impl.h"
#include "group_impl.h"
#include "ecmult_gen_impl.h"
int main(int argc, char **argv) {
secp256k1_ecmult_gen_context_t ctx;
int inner;
int outer;
FILE* fp;
(void)argc;
(void)argv;
fp = fopen("src/ecmult_static_context.h","w");
if (fp == NULL) {
fprintf(stderr, "Could not open src/ecmult_static_context.h for writing!\n");
return -1;
}
fprintf(fp, "#ifndef _SECP256K1_ECMULT_STATIC_CONTEXT_\n");
fprintf(fp, "#define _SECP256K1_ECMULT_STATIC_CONTEXT_\n");
fprintf(fp, "#include \"group.h\"\n");
fprintf(fp, "#define SC SECP256K1_GE_STORAGE_CONST\n");
fprintf(fp, "static const secp256k1_ge_storage_t secp256k1_ecmult_static_context[64][16] = {\n");
secp256k1_ecmult_gen_context_init(&ctx);
secp256k1_ecmult_gen_context_build(&ctx);
for(outer = 0; outer != 64; outer++) {
fprintf(fp,"{\n");
for(inner = 0; inner != 16; inner++) {
fprintf(fp," SC(%uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu)", SECP256K1_GE_STORAGE_CONST_GET((*ctx.prec)[outer][inner]));
if (inner != 15) {
fprintf(fp,",\n");
} else {
fprintf(fp,"\n");
}
}
if (outer != 63) {
fprintf(fp,"},\n");
} else {
fprintf(fp,"}\n");
}
}
fprintf(fp,"};\n");
secp256k1_ecmult_gen_context_clear(&ctx);
fprintf(fp, "#undef SC\n");
fprintf(fp, "#endif\n");
fclose(fp);
return 0;
}

2
src/group.h

@ -38,6 +38,8 @@ typedef struct { @@ -38,6 +38,8 @@ typedef struct {
#define SECP256K1_GE_STORAGE_CONST(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) {SECP256K1_FE_STORAGE_CONST((a),(b),(c),(d),(e),(f),(g),(h)), SECP256K1_FE_STORAGE_CONST((i),(j),(k),(l),(m),(n),(o),(p))}
#define SECP256K1_GE_STORAGE_CONST_GET(t) SECP256K1_FE_STORAGE_CONST_GET(t.x), SECP256K1_FE_STORAGE_CONST_GET(t.y)
/** Set a group element equal to the point at infinity */
static void secp256k1_ge_set_infinity(secp256k1_ge_t *r);

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