#
# format_test_vector.py
# -----------------------------------------
# Formats test vector for x25519_fpga_model
#
# Author: Pavel Shatov
# Copyright (c) 2017-2018, NORDUnet A/S
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
# - Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# - Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# - Neither the name of the NORDUnet nor the names of its contributors may
# be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
#
USAGE = "USAGE: format_test_vector.py [openssl_binary]"
#
#
# This script reads the test vector generated by regenerate_test_vector.py
# and writes nicely formatted C header file and Verilog include file.
#
#
# IMPORTANT: This will only work with OpenSSL 1.1.0, version 1.0.2 doesn't
# support the X25519 algoritm. If you system library is the older version,
# you can pass location of specific OpenSSL binary to use on the command line.
#
#
# imports
#
import sys
import subprocess
import pysodium
#
# variables
#
OPENSSL = ""
#
# format one test vector
#
def format_c_header( f,
da, qax,
db, qbx,
qabx):
# convert to integers
da_int = int(da.hex(), 16)
db_int = int(db.hex(), 16)
qax_int = int(qax.hex(), 16)
qbx_int = int(qbx.hex(), 16)
qabx_int = int(qabx.hex(), 16)
# write all numbers in vector
format_c_array(f, da_int, "#define X25519_DA" + " \\\n")
format_c_array(f, qax_int, "#define X25519_QA_X" + " \\\n")
format_c_array(f, db_int, "#define X25519_DB" + " \\\n")
format_c_array(f, qbx_int, "#define X25519_QB_X" + " \\\n")
format_c_array(f, qabx_int, "#define X25519_QAB_X" + " \\\n")
# #
# # format one test vector
# #
# def format_verilog_include( f, curve, n,
# da, qax, qay,
# db, qbx, qby,
# sx, sy,
# gx, gy,
# hx, hy,
# qa2x, qa2y,
# qb2x, qb2y):
# if curve == CURVE_P256:
# curve_str = "P_256"
# msb_index = "255"
# if curve == CURVE_P384:
# curve_str = "P_384"
# msb_index = "383"
# # write all numbers in vector
# format_verilog_concatenation(f, n, "localparam [" + msb_index + ":0] " + curve_str + "_N" + " =\n")
# format_verilog_concatenation(f, da, "localparam [" + msb_index + ":0] " + curve_str + "_DA" + " =\n")
# format_verilog_concatenation(f, qax, "localparam [" + msb_index + ":0] " + curve_str + "_QA_X" + " =\n")
# format_verilog_concatenation(f, qay, "localparam [" + msb_index + ":0] " + curve_str + "_QA_Y" + " =\n")
# format_verilog_concatenation(f, qa2x, "localparam [" + msb_index + ":0] " + curve_str + "_QA2_X" + " =\n")
# format_verilog_concatenation(f, qa2y, "localparam [" + msb_index + ":0] " + curve_str + "_QA2_Y" + " =\n")
# format_verilog_concatenation(f, db, "localparam [" + msb_index + ":0] " + curve_str + "_DB" + " =\n")
# format_verilog_concatenation(f, qbx, "localparam [" + msb_index + ":0] " + curve_str + "_QB_X" + " =\n")
# format_verilog_concatenation(f, qby, "localparam [" + msb_index + ":0] " + curve_str + "_QB_Y" + " =\n")
# format_verilog_concatenation(f, qb2x, "localparam [" + msb_index + ":0] " + curve_str + "_QB2_X" + " =\n")
# format_verilog_concatenation(f, qb2y, "localparam [" + msb_index + ":0] " + curve_str + "_QB2_Y" + " =\n")
# format_verilog_concatenation(f, sx, "localparam [" + msb_index + ":0] " + curve_str + "_S_X" + " =\n")
# format_verilog_concatenation(f, sy, "localparam [" + msb_index + ":0] " + curve_str + "_S_Y" + " =\n")
# format_verilog_concatenation(f, gx, "localparam [" + msb_index + ":0] " + curve_str + "_G_X" + " =\n")
# format_verilog_concatenation(f, gy, "localparam [" + msb_index + ":0] " + curve_str + "_G_Y" + " =\n")
# format_verilog_concatenation(f, hx, "localparam [" + msb_index + ":0] " + curve_str + "_H_X" + " =\n")
# format_verilog_concatenation(f, hy, "localparam [" + msb_index + ":0] " + curve_str + "_H_Y" + " =\n")
#
# nicely format multi-word integer into C array initializer
#
def format_c_array(f, n, s):
# print '#define XYZ \'
f.write(s)
# convert number to hex string and prepend it with zeroes if necessary
n_hex = hex(n).lstrip("0x").rstrip("L")
while (len(n_hex) % 8) > 0:
n_hex = "0" + n_hex
# get number of 32-bit words
num_words = len(n_hex) // 8
# print all words in n
w = 0
while w < num_words:
n_part = ""
# add tab for every new line
if w == 0:
n_part += "\t{"
elif (w % 4) == 0:
n_part += "\t "
# add current word
n_part += "0x" + n_hex[8 * w : 8 * (w + 1)]
# add separator or newline
if (w + 1) == num_words:
n_part += "}\n"
else:
n_part += ", "
if (w % 4) == 3:
n_part += "\\\n"
w += 1
# write current part
f.write(n_part)
# write final newline
f.write("\n")
# def format_verilog_concatenation(f, n, s):
# # print 'localparam ZZZ ='
# f.write(s)
# # convert number to hex string and prepend it with zeroes if necessary
# n_hex = hex(n).split("0x")[1]
# while (len(n_hex) % 8) > 0:
# n_hex = "0" + n_hex
# # get number of 32-bit words
# num_words = len(n_hex) // 8
# # print all words in n
# w = 0
# while w < num_words:
# n_part = ""
# if w == 0:
# n_part += "\t{"
# elif (w % 4) == 0:
# n_part += "\t "
# n_part += "32'h" + n_hex[8 * w : 8 * (w + 1)]
# if (w + 1) == num_words:
# n_part += "};\n"
# else:
# n_part += ", "
# if (w % 4) == 3:
# n_part += "\n"
# w += 1
# f.write(n_part)
# f.write("\n")
#
# returns d, qx where
# d is private key and qx is the corresponding public key
#
def get_key(openssl, party):
# generate private key filename
key_file = party + ".key"
# retrieve key components using openssl
openssl_command = [openssl, "pkey", "-in", key_file, "-noout", "-text"]
openssl_stdout = subprocess.check_output(openssl_command).decode("utf-8")
stdout_lines = openssl_stdout.splitlines()
key_priv = ""
key_pub = ""
found_priv = False
found_pub = False
# process lines looking for "priv:" and "pub:" markers
for line in stdout_lines:
# found private key marker?
if line == "priv:":
found_priv = True
found_pub = False
continue
# found public key marker?
if line == "pub:":
found_pub = True
found_priv = False
continue
# found part of private key?
if found_priv:
if not line.startswith(" "):
found_priv = False
continue
else:
key_priv += line.strip()
# found part of public key?
if found_pub:
if not line.startswith(" "):
found_pub = False
continue
else:
key_pub += line.strip()
# do some cleanup and sanity checking on private key
# * remove colons
# * check length (256 bits or 384 bits)
key_priv = key_priv.replace(":", "")
if len(key_priv) != (256 / 4): sys.exit()
# do some cleanup and sanity checking on public key
# * remove colons
# * check length (256 bits)
key_pub = key_pub.replace(":", "")
if len(key_pub) != (256 / 4): sys.exit()
# convert to byte arrays
key_priv_bytes = bytes.fromhex(key_priv)
key_pub_bytes = bytes.fromhex(key_pub)
# change byte order to msb...lsb
key_priv_bytes = key_priv_bytes[::-1]
key_pub_bytes = key_pub_bytes[::-1]
# convert to integers
key_priv_int = int(key_priv_bytes.hex(), 16)
key_pub_int = int(key_pub_bytes.hex(), 16)
# another sanity check (make sure, that key_pub is actually key_priv * G)
key_pub_calc_bytes = pysodium.crypto_scalarmult_curve25519_base(key_priv_bytes[::-1])[::-1]
key_pub_calc_int = int(key_pub_calc_bytes.hex(), 16)
if (key_pub_int != key_pub_calc_int): sys.exit()
# done
return key_priv_bytes, key_pub_bytes
#
# returns the shared secret key
#
def calc_shared_key(key_priv_bytes, key_pub_bytes):
key_shared_bytes = pysodium.crypto_scalarmult_curve25519(key_priv_bytes[::-1], key_pub_bytes[::-1])[::-1]
return key_shared_bytes
if __name__ == "__main__":
# detect whether user requested some specific binary
if len(sys.argv) == 1:
OPENSSL = "openssl"
print("Using system OpenSSL library.")
elif len(sys.argv) == 2:
OPENSSL = sys.argv[1]
print("Using OpenSSL binary '" + OPENSSL + "'...")
else:
print(USAGE)
if len(OPENSSL) > 0:
# open output files
file_h = open('x25519_test_vector.h', 'w')
#file_v = open('ecdh_test_vectors.v', 'w')
# write headers
file_h.write("/* Generated automatically, do not edit. */\n\n")
#file_v.write("/* Generated automatically, do not edit. */\n\n")
# load keys
da, qax = get_key(OPENSSL, "alice")
db, qbx = get_key(OPENSSL, "bob")
# we derive the shared secret two different ways (from Alice's and
# from Bob's perspective, they must be identical of course
qabx = calc_shared_key(da, qbx) # Alice's secret
qbax = calc_shared_key(db, qax) # Bob's secret
if (qabx != qbax): sys.exit()
print("Derived shared secret.");
# format numbers and write to file
format_c_header( file_h,
da, qax,
db, qbx,
qabx)
# format_verilog_include( file_v, next_curve, n,
# da, qax, qay,
# db, qbx, qby,
# QAB.x, QBA.y,
# G.x, G.y,
# H.x, H.y,
# QA2.x, QA2.y,
# QB2.x, QB2.y)
# done
file_h.close()
#file_v.close()
# everything went just fine
print("Test vector formatted.")
#
# End of file
#
