From fdfa5bfefdde316688a3c8021bd3528c5273b0f4 Mon Sep 17 00:00:00 2001 From: NIIBE Yutaka Date: Thu, 25 Feb 2016 12:01:10 +0900 Subject: mpi: Normalize EXPO for mpi_powm. * mpi/mpi-pow.c (gcry_mpi_powm): Normalize EP. -- Thanks to Dan Fandrich for the report with a reproducible test case. GnuPG-bug-id: 2256 Signed-off-by: NIIBE Yutaka --- mpi/mpi-pow.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mpi/mpi-pow.c b/mpi/mpi-pow.c index 0be153fe..a780ebd1 100644 --- a/mpi/mpi-pow.c +++ b/mpi/mpi-pow.c @@ -83,6 +83,7 @@ _gcry_mpi_powm (gcry_mpi_t res, rp = res->d; ep = expo->d; + MPN_NORMALIZE(ep, esize); if (!msize) _gcry_divide_by_zero(); @@ -429,6 +430,9 @@ _gcry_mpi_powm (gcry_mpi_t res, size = 2 * msize; msign = mod->sign; + ep = expo->d; + MPN_NORMALIZE(ep, esize); + if (esize * BITS_PER_MPI_LIMB > 512) W = 5; else if (esize * BITS_PER_MPI_LIMB > 256) @@ -445,7 +449,6 @@ _gcry_mpi_powm (gcry_mpi_t res, bsec = mpi_is_secure(base); rp = res->d; - ep = expo->d; if (!msize) _gcry_divide_by_zero(); -- cgit v1.2.1