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/* mpiutil.ac - Utility functions for MPI
* Copyright (C) 1998, 2000, 2001, 2002, 2003,
* 2007 Free Software Foundation, Inc.
* Copyright (C) 2013 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "g10lib.h"
#include "mpi-internal.h"
#include "mod-source-info.h"
#include "const-time.h"
#if SIZEOF_UNSIGNED_INT == 2
# define MY_UINT_MAX 0xffff
/* (visual check: 0123 ) */
#elif SIZEOF_UNSIGNED_INT == 4
# define MY_UINT_MAX 0xffffffff
/* (visual check: 01234567 ) */
#elif SIZEOF_UNSIGNED_INT == 8
# define MY_UINT_MAX 0xffffffffffffffff
/* (visual check: 0123456789abcdef ) */
#else
# error Need MY_UINT_MAX for this limb size
#endif
/* Constants allocated right away at startup. */
static gcry_mpi_t constants[MPI_NUMBER_OF_CONSTANTS];
const char *
_gcry_mpi_get_hw_config (void)
{
return mod_source_info + 1;
}
/* Initialize the MPI subsystem. This is called early and allows to
do some initialization without taking care of threading issues. */
gcry_err_code_t
_gcry_mpi_init (void)
{
int idx;
unsigned long value;
for (idx=0; idx < MPI_NUMBER_OF_CONSTANTS; idx++)
{
switch (idx)
{
case MPI_C_ZERO: value = 0; break;
case MPI_C_ONE: value = 1; break;
case MPI_C_TWO: value = 2; break;
case MPI_C_THREE: value = 3; break;
case MPI_C_FOUR: value = 4; break;
case MPI_C_EIGHT: value = 8; break;
default: log_bug ("invalid mpi_const selector %d\n", idx);
}
constants[idx] = mpi_alloc_set_ui (value);
constants[idx]->flags = (16|32);
}
return 0;
}
/****************
* Note: It was a bad idea to use the number of limbs to allocate
* because on a alpha the limbs are large but we normally need
* integers of n bits - So we should change this to bits (or bytes).
*
* But mpi_alloc is used in a lot of places :-(. New code
* should use mpi_new.
*/
gcry_mpi_t
_gcry_mpi_alloc( unsigned nlimbs )
{
gcry_mpi_t a;
a = xmalloc( sizeof *a );
a->d = nlimbs? mpi_alloc_limb_space( nlimbs, 0 ) : NULL;
a->alloced = nlimbs;
a->nlimbs = 0;
a->sign = 0;
a->flags = 0;
return a;
}
gcry_mpi_t
_gcry_mpi_alloc_secure( unsigned nlimbs )
{
gcry_mpi_t a;
a = xmalloc( sizeof *a );
a->d = nlimbs? mpi_alloc_limb_space( nlimbs, 1 ) : NULL;
a->alloced = nlimbs;
a->flags = 1;
a->nlimbs = 0;
a->sign = 0;
return a;
}
mpi_ptr_t
_gcry_mpi_alloc_limb_space( unsigned int nlimbs, int secure )
{
mpi_ptr_t p;
size_t len;
len = (nlimbs ? nlimbs : 1) * sizeof (mpi_limb_t);
p = secure ? xmalloc_secure (len) : xmalloc (len);
if (! nlimbs)
*p = 0;
return p;
}
void
_gcry_mpi_free_limb_space( mpi_ptr_t a, unsigned int nlimbs)
{
if (a)
{
size_t len = nlimbs * sizeof(mpi_limb_t);
/* If we have information on the number of allocated limbs, we
better wipe that space out. This is a failsafe feature if
secure memory has been disabled or was not properly
implemented in user provided allocation functions. */
if (len)
wipememory (a, len);
xfree(a);
}
}
void
_gcry_mpi_assign_limb_space( gcry_mpi_t a, mpi_ptr_t ap, unsigned int nlimbs )
{
_gcry_mpi_free_limb_space (a->d, a->alloced);
a->d = ap;
a->alloced = nlimbs;
}
/****************
* Resize the array of A to NLIMBS. The additional space is cleared
* (set to 0).
*/
void
_gcry_mpi_resize (gcry_mpi_t a, unsigned nlimbs)
{
size_t i;
if (nlimbs <= a->alloced)
{
/* We only need to clear the new space (this is a nop if the
limb space is already of the correct size. */
for (i=a->nlimbs; i < a->alloced; i++)
a->d[i] = 0;
return;
}
/* Actually resize the limb space. */
if (a->d)
{
a->d = xrealloc (a->d, nlimbs * sizeof (mpi_limb_t));
for (i=a->nlimbs; i < nlimbs; i++)
a->d[i] = 0;
}
else
{
if (a->flags & 1)
/* Secure memory is wanted. */
a->d = xcalloc_secure (nlimbs , sizeof (mpi_limb_t));
else
/* Standard memory. */
a->d = xcalloc (nlimbs , sizeof (mpi_limb_t));
}
a->alloced = nlimbs;
}
void
_gcry_mpi_clear( gcry_mpi_t a )
{
if (mpi_is_immutable (a))
{
mpi_immutable_failed ();
return;
}
a->nlimbs = 0;
a->flags = 0;
}
void
_gcry_mpi_free( gcry_mpi_t a )
{
if (!a )
return;
if ((a->flags & 32))
{
#if GPGRT_VERSION_NUMBER >= 0x011600 /* 1.22 */
gpgrt_annotate_leaked_object(a);
#endif
return; /* Never release a constant. */
}
if ((a->flags & 4))
xfree( a->d );
else
{
_gcry_mpi_free_limb_space(a->d, a->alloced);
}
/* Check that the flags makes sense. We better allow for bit 1
(value 2) for backward ABI compatibility. */
if ((a->flags & ~(1|2|4|16
|GCRYMPI_FLAG_USER1
|GCRYMPI_FLAG_USER2
|GCRYMPI_FLAG_USER3
|GCRYMPI_FLAG_USER4)))
log_bug("invalid flag value in mpi_free\n");
xfree (a);
}
void
_gcry_mpi_immutable_failed (void)
{
log_info ("Warning: trying to change an immutable MPI\n");
}
static void
mpi_set_secure( gcry_mpi_t a )
{
mpi_ptr_t ap, bp;
if ( (a->flags & 1) )
return;
a->flags |= 1;
ap = a->d;
if (!a->nlimbs)
{
gcry_assert (!ap);
return;
}
bp = mpi_alloc_limb_space (a->alloced, 1);
MPN_COPY( bp, ap, a->nlimbs );
a->d = bp;
_gcry_mpi_free_limb_space (ap, a->alloced);
}
gcry_mpi_t
_gcry_mpi_set_opaque (gcry_mpi_t a, void *p, unsigned int nbits)
{
if (!a)
a = mpi_alloc(0);
if (mpi_is_immutable (a))
{
mpi_immutable_failed ();
return a;
}
if( a->flags & 4 )
xfree (a->d);
else
_gcry_mpi_free_limb_space (a->d, a->alloced);
a->d = p;
a->alloced = 0;
a->nlimbs = 0;
a->sign = nbits;
a->flags = 4 | (a->flags & (GCRYMPI_FLAG_USER1|GCRYMPI_FLAG_USER2
|GCRYMPI_FLAG_USER3|GCRYMPI_FLAG_USER4));
if (_gcry_is_secure (a->d))
a->flags |= 1;
return a;
}
gcry_mpi_t
_gcry_mpi_set_opaque_copy (gcry_mpi_t a, const void *p, unsigned int nbits)
{
void *d;
unsigned int n;
n = (nbits+7)/8;
d = _gcry_is_secure (p)? xtrymalloc_secure (n) : xtrymalloc (n);
if (!d)
return NULL;
memcpy (d, p, n);
return mpi_set_opaque (a, d, nbits);
}
void *
_gcry_mpi_get_opaque (gcry_mpi_t a, unsigned int *nbits)
{
if( !(a->flags & 4) )
log_bug("mpi_get_opaque on normal mpi\n");
if( nbits )
*nbits = a->sign;
return a->d;
}
void *
_gcry_mpi_get_opaque_copy (gcry_mpi_t a, unsigned int *nbits)
{
const void *s;
void *d;
unsigned int n;
s = mpi_get_opaque (a, nbits);
if (!s && nbits)
return NULL;
n = (*nbits+7)/8;
d = _gcry_is_secure (s)? xtrymalloc_secure (n) : xtrymalloc (n);
if (d)
memcpy (d, s, n);
return d;
}
/****************
* Note: This copy function should not interpret the MPI
* but copy it transparently.
*/
gcry_mpi_t
_gcry_mpi_copy (gcry_mpi_t a)
{
int i;
gcry_mpi_t b;
if( a && (a->flags & 4) ) {
void *p = NULL;
if (a->sign) {
p = _gcry_is_secure(a->d)? xmalloc_secure ((a->sign+7)/8)
: xmalloc ((a->sign+7)/8);
if (a->d)
memcpy( p, a->d, (a->sign+7)/8 );
}
b = mpi_set_opaque( NULL, p, a->sign );
b->flags = a->flags;
b->flags &= ~(16|32); /* Reset the immutable and constant flags. */
}
else if( a ) {
b = mpi_is_secure(a)? mpi_alloc_secure( a->nlimbs )
: mpi_alloc( a->nlimbs );
b->nlimbs = a->nlimbs;
b->sign = a->sign;
b->flags = a->flags;
b->flags &= ~(16|32); /* Reset the immutable and constant flags. */
for(i=0; i < b->nlimbs; i++ )
b->d[i] = a->d[i];
}
else
b = NULL;
return b;
}
/* Return true if A is negative. */
int
_gcry_mpi_is_neg (gcry_mpi_t a)
{
if (a->sign && _gcry_mpi_cmp_ui (a, 0))
return 1;
else
return 0;
}
/* W = - U */
void
_gcry_mpi_neg (gcry_mpi_t w, gcry_mpi_t u)
{
if (w != u)
mpi_set (w, u);
else if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return;
}
w->sign = !u->sign;
}
/* W = [W] */
void
_gcry_mpi_abs (gcry_mpi_t w)
{
if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return;
}
w->sign = 0;
}
/****************
* This function allocates an MPI which is optimized to hold
* a value as large as the one given in the argument and allocates it
* with the same flags as A.
*/
gcry_mpi_t
_gcry_mpi_alloc_like( gcry_mpi_t a )
{
gcry_mpi_t b;
if( a && (a->flags & 4) ) {
int n = (a->sign+7)/8;
void *p = _gcry_is_secure(a->d)? xtrymalloc_secure (n)
: xtrymalloc (n);
memcpy( p, a->d, n );
b = mpi_set_opaque( NULL, p, a->sign );
}
else if( a ) {
b = mpi_is_secure(a)? mpi_alloc_secure( a->nlimbs )
: mpi_alloc( a->nlimbs );
b->nlimbs = 0;
b->sign = 0;
b->flags = a->flags;
}
else
b = NULL;
return b;
}
/* Set U into W and release U. If W is NULL only U will be released. */
void
_gcry_mpi_snatch (gcry_mpi_t w, gcry_mpi_t u)
{
if (w)
{
if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return;
}
_gcry_mpi_assign_limb_space (w, u->d, u->alloced);
w->nlimbs = u->nlimbs;
w->sign = u->sign;
w->flags = u->flags;
u->alloced = 0;
u->nlimbs = 0;
u->d = NULL;
}
_gcry_mpi_free (u);
}
gcry_mpi_t
_gcry_mpi_set (gcry_mpi_t w, gcry_mpi_t u)
{
mpi_ptr_t wp, up;
mpi_size_t usize = u->nlimbs;
int usign = u->sign;
if (!w)
w = _gcry_mpi_alloc( mpi_get_nlimbs(u) );
if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return w;
}
RESIZE_IF_NEEDED(w, usize);
wp = w->d;
up = u->d;
MPN_COPY( wp, up, usize );
w->nlimbs = usize;
w->flags = u->flags;
w->flags &= ~(16|32); /* Reset the immutable and constant flags. */
w->sign = usign;
return w;
}
/****************
* Set the value of W by the one of U, when SET is 1.
* Leave the value when SET is 0.
* This implementation should be constant-time regardless of SET.
*/
gcry_mpi_t
_gcry_mpi_set_cond (gcry_mpi_t w, const gcry_mpi_t u, unsigned long set)
{
/* Note: dual mask with AND/OR used for EM leakage mitigation */
mpi_limb_t mask1 = _gcry_ct_vzero - set;
mpi_limb_t mask2 = set - _gcry_ct_vone;
mpi_size_t i;
mpi_size_t nlimbs = u->alloced;
mpi_limb_t xu;
mpi_limb_t xw;
mpi_limb_t *uu = u->d;
mpi_limb_t *uw = w->d;
if (w->alloced != u->alloced)
log_bug ("mpi_set_cond: different sizes\n");
for (i = 0; i < nlimbs; i++)
{
xu = uu[i];
xw = uw[i];
uw[i] = (xw & mask2) | (xu & mask1);
}
xu = u->nlimbs;
xw = w->nlimbs;
w->nlimbs = (xw & mask2) | (xu & mask1);
xu = u->sign;
xw = w->sign;
w->sign = (xw & mask2) | (xu & mask1);
return w;
}
gcry_mpi_t
_gcry_mpi_set_ui (gcry_mpi_t w, unsigned long u)
{
if (!w)
w = _gcry_mpi_alloc (1);
/* FIXME: If U is 0 we have no need to resize and thus possible
allocating the the limbs. */
if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return w;
}
RESIZE_IF_NEEDED(w, 1);
w->d[0] = u;
w->nlimbs = u? 1:0;
w->sign = 0;
w->flags = 0;
return w;
}
/* If U is non-negative and small enough store it as an unsigned int
* at W. If the value does not fit into an unsigned int or is
* negative return GPG_ERR_ERANGE. Note that we return an unsigned
* int so that the value can be used with the bit test functions; in
* contrast the other _ui functions take an unsigned long so that on
* some platforms they may accept a larger value. On error the value
* at W is not changed. */
gcry_err_code_t
_gcry_mpi_get_ui (unsigned int *w, gcry_mpi_t u)
{
mpi_limb_t x;
if (u->nlimbs > 1 || u->sign)
return GPG_ERR_ERANGE;
x = (u->nlimbs == 1) ? u->d[0] : 0;
if (sizeof (x) > sizeof (unsigned int) && x > MY_UINT_MAX)
return GPG_ERR_ERANGE;
*w = x;
return 0;
}
gcry_mpi_t
_gcry_mpi_alloc_set_ui( unsigned long u)
{
gcry_mpi_t w = mpi_alloc(1);
w->d[0] = u;
w->nlimbs = u? 1:0;
w->sign = 0;
return w;
}
void
_gcry_mpi_swap (gcry_mpi_t a, gcry_mpi_t b)
{
struct gcry_mpi tmp;
tmp = *a; *a = *b; *b = tmp;
}
/****************
* Swap the value of A and B, when SWAP is 1.
* Leave the value when SWAP is 0.
* This implementation should be constant-time regardless of SWAP.
*/
void
_gcry_mpi_swap_cond (gcry_mpi_t a, gcry_mpi_t b, unsigned long swap)
{
/* Note: dual mask with AND/OR used for EM leakage mitigation */
mpi_limb_t mask1 = _gcry_ct_vzero - swap;
mpi_limb_t mask2 = swap - _gcry_ct_vone;
mpi_size_t i;
mpi_size_t nlimbs;
mpi_limb_t *ua = a->d;
mpi_limb_t *ub = b->d;
mpi_limb_t xa;
mpi_limb_t xb;
if (a->alloced > b->alloced)
nlimbs = b->alloced;
else
nlimbs = a->alloced;
if (a->nlimbs > nlimbs || b->nlimbs > nlimbs)
log_bug ("mpi_swap_cond: different sizes\n");
for (i = 0; i < nlimbs; i++)
{
xa = ua[i];
xb = ub[i];
ua[i] = (xa & mask2) | (xb & mask1);
ub[i] = (xa & mask1) | (xb & mask2);
}
xa = a->nlimbs;
xb = b->nlimbs;
a->nlimbs = (xa & mask2) | (xb & mask1);
b->nlimbs = (xa & mask1) | (xb & mask2);
xa = a->sign;
xb = b->sign;
a->sign = (xa & mask2) | (xb & mask1);
b->sign = (xa & mask1) | (xb & mask2);
}
/****************
* Set bit N of A, when SET is 1.
* This implementation should be constant-time regardless of SET.
*/
void
_gcry_mpi_set_bit_cond (gcry_mpi_t a, unsigned int n, unsigned long set)
{
unsigned int limbno, bitno;
mpi_limb_t set_the_bit = !!set;
limbno = n / BITS_PER_MPI_LIMB;
bitno = n % BITS_PER_MPI_LIMB;
a->d[limbno] |= (set_the_bit<<bitno);
}
gcry_mpi_t
_gcry_mpi_new (unsigned int nbits)
{
return _gcry_mpi_alloc ( (nbits+BITS_PER_MPI_LIMB-1)
/ BITS_PER_MPI_LIMB );
}
gcry_mpi_t
_gcry_mpi_snew (unsigned int nbits)
{
return _gcry_mpi_alloc_secure ( (nbits+BITS_PER_MPI_LIMB-1)
/ BITS_PER_MPI_LIMB );
}
void
_gcry_mpi_release( gcry_mpi_t a )
{
_gcry_mpi_free( a );
}
void
_gcry_mpi_randomize (gcry_mpi_t w,
unsigned int nbits, enum gcry_random_level level)
{
unsigned char *p;
size_t nbytes = (nbits+7)/8;
if (mpi_is_immutable (w))
{
mpi_immutable_failed ();
return;
}
if (level == GCRY_WEAK_RANDOM)
{
p = mpi_is_secure(w) ? xmalloc_secure (nbytes)
: xmalloc (nbytes);
_gcry_create_nonce (p, nbytes);
}
else
{
p = mpi_is_secure(w) ? _gcry_random_bytes_secure (nbytes, level)
: _gcry_random_bytes (nbytes, level);
}
_gcry_mpi_set_buffer( w, p, nbytes, 0 );
xfree (p);
}
void
_gcry_mpi_set_flag (gcry_mpi_t a, enum gcry_mpi_flag flag)
{
switch (flag)
{
case GCRYMPI_FLAG_SECURE: mpi_set_secure(a); break;
case GCRYMPI_FLAG_CONST: a->flags |= (16|32); break;
case GCRYMPI_FLAG_IMMUTABLE: a->flags |= 16; break;
case GCRYMPI_FLAG_USER1:
case GCRYMPI_FLAG_USER2:
case GCRYMPI_FLAG_USER3:
case GCRYMPI_FLAG_USER4: a->flags |= flag; break;
case GCRYMPI_FLAG_OPAQUE:
default: log_bug("invalid flag value\n");
}
}
void
_gcry_mpi_clear_flag (gcry_mpi_t a, enum gcry_mpi_flag flag)
{
(void)a; /* Not yet used. */
switch (flag)
{
case GCRYMPI_FLAG_IMMUTABLE:
if (!(a->flags & 32))
a->flags &= ~16;
break;
case GCRYMPI_FLAG_USER1:
case GCRYMPI_FLAG_USER2:
case GCRYMPI_FLAG_USER3:
case GCRYMPI_FLAG_USER4:
a->flags &= ~flag;
break;
case GCRYMPI_FLAG_CONST:
case GCRYMPI_FLAG_SECURE:
case GCRYMPI_FLAG_OPAQUE:
default: log_bug("invalid flag value\n");
}
}
int
_gcry_mpi_get_flag (gcry_mpi_t a, enum gcry_mpi_flag flag)
{
switch (flag)
{
case GCRYMPI_FLAG_SECURE: return !!(a->flags & 1);
case GCRYMPI_FLAG_OPAQUE: return !!(a->flags & 4);
case GCRYMPI_FLAG_IMMUTABLE: return !!(a->flags & 16);
case GCRYMPI_FLAG_CONST: return !!(a->flags & 32);
case GCRYMPI_FLAG_USER1:
case GCRYMPI_FLAG_USER2:
case GCRYMPI_FLAG_USER3:
case GCRYMPI_FLAG_USER4: return !!(a->flags & flag);
default: log_bug("invalid flag value\n");
}
/*NOTREACHED*/
return 0;
}
/* Return a constant MPI descripbed by NO which is one of the
MPI_C_xxx macros. There is no need to copy this returned value; it
may be used directly. */
gcry_mpi_t
_gcry_mpi_const (enum gcry_mpi_constants no)
{
if ((int)no < 0 || no > MPI_NUMBER_OF_CONSTANTS)
log_bug("invalid mpi_const selector %d\n", no);
if (!constants[no])
log_bug("MPI subsystem not initialized\n");
return constants[no];
}

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