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SubjectRe: [PATCH v5 2/8] lib/mpi: Extend the MPI library
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On 2020/7/10 21:12, Marcelo Henrique Cerri wrote:
> Hi, Tianjia.
>
> On Thu, Jul 09, 2020 at 04:40:09PM +0800, Tianjia Zhang wrote:
>> Expand the mpi library based on libgcrypt, and the ECC algorithm of
>> mpi based on libgcrypt requires these functions.
>> Some other algorithms will be developed based on mpi ecc, such as SM2.
>>
>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>> ---
>> include/linux/mpi.h | 88 +++++++++++
>> lib/mpi/Makefile | 5 +
>> lib/mpi/mpi-add.c | 207 +++++++++++++++++++++++++
>> lib/mpi/mpi-bit.c | 251 ++++++++++++++++++++++++++++++
>> lib/mpi/mpi-cmp.c | 46 ++++--
>> lib/mpi/mpi-div.c | 238 +++++++++++++++++++++++++++++
>> lib/mpi/mpi-internal.h | 53 +++++++
>> lib/mpi/mpi-inv.c | 143 ++++++++++++++++++
>> lib/mpi/mpi-mod.c | 155 +++++++++++++++++++
>> lib/mpi/mpi-mul.c | 94 ++++++++++++
>> lib/mpi/mpicoder.c | 336 +++++++++++++++++++++++++++++++++++++++++
>> lib/mpi/mpih-div.c | 294 ++++++++++++++++++++++++++++++++++++
>> lib/mpi/mpih-mul.c | 25 +++
>> lib/mpi/mpiutil.c | 204 +++++++++++++++++++++++++
>> 14 files changed, 2129 insertions(+), 10 deletions(-)
>> create mode 100644 lib/mpi/mpi-add.c
>> create mode 100644 lib/mpi/mpi-div.c
>> create mode 100644 lib/mpi/mpi-inv.c
>> create mode 100644 lib/mpi/mpi-mod.c
>> create mode 100644 lib/mpi/mpi-mul.c
>>
>> diff --git a/lib/mpi/mpi-add.c b/lib/mpi/mpi-add.c
>> new file mode 100644
>> index 000000000000..9afad7832737
>> --- /dev/null
>> +++ b/lib/mpi/mpi-add.c
>> @@ -0,0 +1,207 @@
>> +/* mpi-add.c - MPI functions
>> + * Copyright (C) 1994, 1996, 1998, 2001, 2002,
>> + * 2003 Free Software Foundation, Inc.
>> + *
>> + * This file is part of Libgcrypt.
>> + *
>> + * Note: This code is heavily based on the GNU MP Library.
>> + * Actually it's the same code with only minor changes in the
>> + * way the data is stored; this is to support the abstraction
>> + * of an optional secure memory allocation which may be used
>> + * to avoid revealing of sensitive data due to paging etc.
>> + */
>> +
>> +#include "mpi-internal.h"
>> +
>> +/****************
>> + * Add the unsigned integer V to the mpi-integer U and store the
>> + * result in W. U and V may be the same.
>> + */
>> +void mpi_add_ui(MPI w, MPI u, unsigned long v)
>> +{
>> + mpi_ptr_t wp, up;
>> + mpi_size_t usize, wsize;
>> + int usign, wsign;
>> +
>> + usize = u->nlimbs;
>> + usign = u->sign;
>> + wsign = 0;
>> +
>> + /* If not space for W (and possible carry), increase space. */
>> + wsize = usize + 1;
>> + if (w->alloced < wsize)
>> + mpi_resize(w, wsize);
>
> You are ignoring the mpi_resize() return. I believe these new functions
> need to return an int to indicate errors as mpi_powm() does.
>

Yes, of course. Thanks for pointing it out.

Thanks,
Tianjia

>
>> +
>> + /* These must be after realloc (U may be the same as W). */
>> + up = u->d;
>> + wp = w->d;
>> +
>> + if (!usize) { /* simple */
>> + wp[0] = v;
>> + wsize = v ? 1:0;
>> + } else if (!usign) { /* mpi is not negative */
>> + mpi_limb_t cy;
>> + cy = mpihelp_add_1(wp, up, usize, v);
>> + wp[usize] = cy;
>> + wsize = usize + cy;
>> + } else {
>> + /* The signs are different. Need exact comparison to determine
>> + * which operand to subtract from which.
>> + */
>> + if (usize == 1 && up[0] < v) {
>> + wp[0] = v - up[0];
>> + wsize = 1;
>> + } else {
>> + mpihelp_sub_1(wp, up, usize, v);
>> + /* Size can decrease with at most one limb. */
>> + wsize = usize - (wp[usize-1] == 0);
>> + wsign = 1;
>> + }
>> + }
>> +
>> + w->nlimbs = wsize;
>> + w->sign = wsign;
>> +}
>> +

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