Elliptic curve private-to-public incorrect result on Linux 32 bit #9
Description
Reproducer:
#include <cstdint>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <boost/multiprecision/cpp_int.hpp>
#include <symcrypt.h>
#define CF_CHECK_EQ(expr, res) if ( (expr) != (res) ) { goto end; }
#define CF_CHECK_NE(expr, res) if ( (expr) == (res) ) { goto end; }
extern "C" {
void SymCryptFatal(UINT32 fatalCode) {
(void)fatalCode;
abort();
}
void SymCryptInjectError( PBYTE pbData, SIZE_T cbData ) {
(void)pbData;
(void)cbData;
}
PVOID SymCryptCallbackAlloc( SIZE_T nBytes ) {
return malloc(nBytes);
}
VOID SymCryptCallbackFree( VOID * pMem ) {
free(pMem);
}
SYMCRYPT_ERROR SymCryptCallbackRandom(PBYTE pbBuffer, SIZE_T cbBuffer ) {
abort();
}
SYMCRYPT_CPU_FEATURES
SymCryptCpuFeaturesNeverPresent(void) {
return 0;
}
}
namespace SymCrypt_detail {
static bool EncodeBignum(const std::string s, uint8_t* out, const size_t outSize) {
std::vector<uint8_t> v;
boost::multiprecision::cpp_int c(s);
boost::multiprecision::export_bits(c, std::back_inserter(v), 8);
if ( v.size() > outSize ) {
return false;
}
const auto diff = outSize - v.size();
memset(out, 0, outSize);
memcpy(out + diff, v.data(), v.size());
return true;
}
static std::string toString(const boost::multiprecision::cpp_int& i) {
std::stringstream ss;
ss << i;
if ( ss.str().empty() ) {
return "0";
} else {
return ss.str();
}
}
}
int main(void)
{
SYMCRYPT_ECURVE* curve = nullptr;
SYMCRYPT_ECKEY* key = nullptr;
const SYMCRYPT_ECURVE_PARAMS* curveParams = SymCryptEcurveParamsNistP384;
CF_CHECK_NE(curve = SymCryptEcurveAllocate(curveParams, 0), nullptr);
CF_CHECK_NE(key = SymCryptEckeyAllocate(curve), nullptr);
{
const auto priv_size = SymCryptEckeySizeofPrivateKey(key);
std::vector<uint8_t> priv_bytes(priv_size);
CF_CHECK_EQ(SymCrypt_detail::EncodeBignum(
"15",
priv_bytes.data(),
priv_size), true);
CF_CHECK_EQ(SymCryptEckeySetValue(
priv_bytes.data(), priv_size,
NULL, 0,
SYMCRYPT_NUMBER_FORMAT_MSB_FIRST, SYMCRYPT_ECPOINT_FORMAT_XY,
0, key), SYMCRYPT_NO_ERROR);
}
{
const auto pub_size = SymCryptEckeySizeofPublicKey(key, SYMCRYPT_ECPOINT_FORMAT_XY);
if ( (pub_size % 2) != 0 ) {
abort();
}
std::vector<uint8_t> pub_bytes(pub_size);
CF_CHECK_EQ(SymCryptEckeyGetValue(
key,
NULL, 0,
pub_bytes.data(), pub_size,
SYMCRYPT_NUMBER_FORMAT_MSB_FIRST, SYMCRYPT_ECPOINT_FORMAT_XY,
0), SYMCRYPT_NO_ERROR);
{
boost::multiprecision::cpp_int x, y;
boost::multiprecision::import_bits(x, pub_bytes.begin(), pub_bytes.begin() + (pub_size/2));
boost::multiprecision::import_bits(y, pub_bytes.begin() + (pub_size/2), pub_bytes.end());
std::cout << SymCrypt_detail::toString(x) << std::endl;
std::cout << SymCrypt_detail::toString(y) << std::endl;
}
}
end:
if ( key ) {
/* noret */ SymCryptEckeyFree(key);
}
if ( curve ) {
/* noret */ SymCryptEcurveFree(curve);
}
return 0;
}First, compile SymCrypt like this:
export CC=clang
export CXX=clang++
export CFLAGS="-m32"
export CXXFLAGS="-m32"
git clone --depth 1 https://github.com/microsoft/SymCrypt.git
cd SymCrypt/
# Unittests don't build with clang and are not needed anyway
sed -i "s/^add_subdirectory(unittest)$//g" CMakeLists.txt
mkdir b/
cd b/
setarch i386 cmake ../
make -j$(nproc)Then compile and run the reproducer:
$ $CXX $CXXFLAGS -DSYMCRYPT_IGNORE_PLATFORM -I SymCrypt/inc/ p.cpp SymCrypt/b/lib/i686/Generic/libsymcrypt_common.a
$ ./a.out
3371410058567038036102658371067750911905410377350295952202630426945666718973957844373613366326295398452393
6490343607037185220769843464241451023660093550735871349269711288852702861970840804993910898129495774144414But it should print:
27676427741886189792545170648212433086611990497738896912065553637549098719435212229527415490501936487430563654174219
3256906964515830166357393887851908050144111374947447699655351073133031632026642053647058697111201931251927081270626