/** @brief call the ECC power ladder point-scalar multiply */
msel_status msel_ecc_mul(ecc_ctx_t* ctx)
{
#ifdef USE_SW_ECC
// Get the scalar value
make_mp(scalar, ctx->scalar, ECC_SCALAR_LEN);
make_mp(compressed, ctx->point, ECC_POINT_LEN);
// The sign of y is the 7th bit of the first byte
int y_sign = ctx->point[0] & 0x01;
point_uncompress(&in, compressed, y_sign);
// Do the multiply
point_scalar(&out, &in, scalar);
// Compress the point -- this removes from mont. form
point_compress(compressed, &y_sign, &out);
ctx->point[0] &= 0xfe; ctx->point[0] |= y_sign;
// Load the new point into the buffer
from_mp(ctx->point, compressed, ECC_POINT_LEN);
return MSEL_OK;
#else /* USE_SW_ECC */
return arch_hw_ecc_mul(ctx);
#endif /* USE_SW_ECC */
}
void compress_to_string(char *buf, enum disp_format df,
const struct affine_point *P,
const struct curve_params *cp)
{
int outlen = (df == DF_COMPACT) ? cp->pk_len_compact : cp->pk_len_bin;
if (point_compress(P)) {
gcry_mpi_t x;
x = gcry_mpi_snew(0);
gcry_mpi_add(x, P->x, cp->dp.m);
serialize_mpi(buf, outlen, df, x);
gcry_mpi_release(x);
}
else
serialize_mpi(buf, outlen, df, P->x);
}