diff --git a/scripts/ecp_comb_table.py b/scripts/ecp_comb_table.py new file mode 100755 index 0000000000..bc11431189 --- /dev/null +++ b/scripts/ecp_comb_table.py @@ -0,0 +1,249 @@ +#!/usr/bin/env python3 +""" +Purpose + +This script dumps comb table of ec curve. When you add a new ec curve, you +can use this script to generate codes to define `_T` in ecp_curves.c +""" + +# Copyright The Mbed TLS Contributors +# SPDX-License-Identifier: Apache-2.0 +# +# 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. + +import os +import subprocess +import sys +import tempfile + +HOW_TO_ADD_NEW_CURVE = """ +If you are trying to add new curve, you can follow these steps: + +1. Define curve parameters (_p, _gx, etc...) in ecp_curves.c. +2. Add a macro to define _T to NULL following these parameters. +3. Build mbedcrypto +4. Run this script with an argument of new curve +5. Copy the output of this script into ecp_curves.c and replace the macro added + in Step 2 +6. Rebuild and test if everything is ok + +Replace the in the above with the name of the curve you want to add.""" + +CC = os.getenv('CC', 'cc') +MBEDTLS_LIBRARY_PATH = os.getenv('MBEDTLS_LIBRARY_PATH', "library") + +SRC_DUMP_COMB_TABLE = r''' +#include +#include +#include "mbedtls/ecp.h" +#include "mbedtls/error.h" + +static void dump_mpi_initialize( const char *name, const mbedtls_mpi *d ) +{ + uint8_t buf[128] = {0}; + size_t olen; + uint8_t *p; + + olen = mbedtls_mpi_size( d ); + mbedtls_mpi_write_binary_le( d, buf, olen ); + printf("static const mbedtls_mpi_uint %s[] = {\n", name); + for (p = buf; p < buf + olen; p += 8) { + printf( " BYTES_TO_T_UINT_8( 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X ),\n", + p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7] ); + } + printf("};\n"); +} + +static void dump_T( const mbedtls_ecp_group *grp ) +{ + char name[128]; + + printf( "#if MBEDTLS_ECP_FIXED_POINT_OPTIM == 1\n" ); + + for (size_t i = 0; i < grp->T_size; ++i) { + snprintf( name, sizeof(name), "%s_T_%zu_X", CURVE_NAME, i ); + dump_mpi_initialize( name, &grp->T[i].X ); + + snprintf( name, sizeof(name), "%s_T_%zu_Y", CURVE_NAME, i ); + dump_mpi_initialize( name, &grp->T[i].Y ); + } + printf( "static const mbedtls_ecp_point %s_T[%zu] = {\n", CURVE_NAME, grp->T_size ); + size_t olen; + for (size_t i = 0; i < grp->T_size; ++i) { + int z; + if ( mbedtls_mpi_cmp_int(&grp->T[i].Z, 0) == 0 ) { + z = 0; + } else if ( mbedtls_mpi_cmp_int(&grp->T[i].Z, 1) == 0 ) { + z = 1; + } else { + fprintf( stderr, "Unexpected value of Z (i = %d)\n", (int)i ); + exit( 1 ); + } + printf( " ECP_POINT_INIT_XY_Z%d(%s_T_%zu_X, %s_T_%zu_Y),\n", + z, + CURVE_NAME, i, + CURVE_NAME, i + ); + } + printf("};\n#endif\n\n"); +} + +int main() +{ + int rc; + mbedtls_mpi m; + mbedtls_ecp_point R; + mbedtls_ecp_group grp; + + mbedtls_ecp_group_init( &grp ); + rc = mbedtls_ecp_group_load( &grp, CURVE_ID ); + if (rc != 0) { + char buf[100]; + mbedtls_strerror( rc, buf, sizeof(buf) ); + fprintf( stderr, "mbedtls_ecp_group_load: %s (-0x%x)\n", buf, -rc ); + return 1; + } + grp.T = NULL; + mbedtls_ecp_point_init( &R ); + mbedtls_mpi_init( &m); + mbedtls_mpi_lset( &m, 1 ); + rc = mbedtls_ecp_mul( &grp, &R, &m, &grp.G, NULL, NULL ); + if ( rc != 0 ) { + char buf[100]; + mbedtls_strerror( rc, buf, sizeof(buf) ); + fprintf( stderr, "mbedtls_ecp_mul: %s (-0x%x)\n", buf, -rc ); + return 1; + } + if ( grp.T == NULL ) { + fprintf( stderr, "grp.T is not generated. Please make sure" + "MBEDTLS_ECP_FIXED_POINT_OPTIM is enabled in config.h\n" ); + return 1; + } + dump_T( &grp ); + return 0; +} +''' + +SRC_DUMP_KNOWN_CURVE = r''' +#include +#include +#include "mbedtls/ecp.h" + +int main() { + const mbedtls_ecp_curve_info *info = mbedtls_ecp_curve_list(); + mbedtls_ecp_group grp; + + mbedtls_ecp_group_init( &grp ); + while ( info->name != NULL ) { + mbedtls_ecp_group_load( &grp, info->grp_id ); + if ( mbedtls_ecp_get_type(&grp) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS ) { + printf( " %s", info->name ); + } + info++; + } + printf( "\n" ); + return 0; +} +''' + + +def join_src_path(*args): + return os.path.normpath(os.path.join(os.path.dirname(__file__), "..", *args)) + + +def run_c_source(src, cflags): + """ + Compile and run C source code + :param src: the c language code to run + :param cflags: additional cflags passing to compiler + :return: + """ + binname = tempfile.mktemp(prefix="mbedtls") + fd, srcname = tempfile.mkstemp(prefix="mbedtls", suffix=".c") + srcfile = os.fdopen(fd, mode="w") + srcfile.write(src) + srcfile.close() + args = [CC, + *cflags, + '-I' + join_src_path("include"), + "-o", binname, + '-L' + MBEDTLS_LIBRARY_PATH, + srcname, + '-lmbedcrypto'] + + p = subprocess.run(args=args, check=False) + if p.returncode != 0: + return False + p = subprocess.run(args=[binname], check=False, env={ + 'LD_LIBRARY_PATH': MBEDTLS_LIBRARY_PATH + }) + if p.returncode != 0: + return False + os.unlink(srcname) + os.unlink(binname) + return True + + +def compute_curve(curve): + """compute comb table for curve""" + r = run_c_source( + SRC_DUMP_COMB_TABLE, + [ + '-g', + '-DCURVE_ID=MBEDTLS_ECP_DP_%s' % curve.upper(), + '-DCURVE_NAME="%s"' % curve.lower(), + ]) + if not r: + print("""\ +Unable to compile and run utility.""", file=sys.stderr) + sys.exit(1) + + +def usage(): + print(""" +Usage: python %s ... + +Arguments: + curve Specify one or more curve names (e.g secp256r1) + +All possible curves: """ % sys.argv[0]) + run_c_source(SRC_DUMP_KNOWN_CURVE, []) + print(""" +Environment Variable: + CC Specify which c compile to use to compile utility. + MBEDTLS_LIBRARY_PATH + Specify the path to mbedcrypto library. (e.g. build/library/) + +How to add a new curve: %s""" % HOW_TO_ADD_NEW_CURVE) + + +def run_main(): + shared_lib_path = os.path.normpath(os.path.join(MBEDTLS_LIBRARY_PATH, "libmbedcrypto.so")) + static_lib_path = os.path.normpath(os.path.join(MBEDTLS_LIBRARY_PATH, "libmbedcrypto.a")) + if not os.path.exists(shared_lib_path) and not os.path.exists(static_lib_path): + print("Warning: both '%s' and '%s' are not exists. This script will use " + "the library from your system instead of the library compiled by " + "this source directory.\n" + "You can specify library path using environment variable " + "'MBEDTLS_LIBRARY_PATH'." % (shared_lib_path, static_lib_path), + file=sys.stderr) + + if len(sys.argv) <= 1: + usage() + else: + for curve in sys.argv[1:]: + compute_curve(curve) + + +if __name__ == '__main__': + run_main()