/*	$OpenBSD: math_group.c,v 1.2 1998/11/15 00:44:00 niklas Exp $	*/

/*
 * Copyright (c) 1998 Niels Provos.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Ericsson Radio Systems.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <sys/param.h>
#include <gmp.h>
#include <stdlib.h>
#include <string.h>

#include "gmp_util.h"
#include "math_2n.h"
#include "math_ec2n.h"
#include "math_group.h"

#include "log.h"
#include "sysdep.h"

/* We do not want to export these definitions */
int modp_getlen (struct group *);
void modp_getraw (struct group *, mpz_ptr, u_int8_t *);
void modp_setraw (struct group *, mpz_ptr, u_int8_t *, int);
void modp_setrandom (struct group *, mpz_ptr);
void modp_operation (struct group *, mpz_ptr, mpz_ptr, mpz_ptr);

int ec2n_getlen (struct group *);
void ec2n_getraw (struct group *, ec2np_ptr, u_int8_t *);
void ec2n_setraw (struct group *, ec2np_ptr, u_int8_t *, int);
void ec2n_setrandom (struct group *, ec2np_ptr);
void ec2n_operation (struct group *, ec2np_ptr, ec2np_ptr, ec2np_ptr);

struct ec2n_group {
  ec2np_t gen;				/* Generator */
  ec2ng_t grp;
  ec2np_t a, b, c, d;
};

struct modp_group {
  mpz_t gen;				/* Generator */
  mpz_t p;				/* Prime */
  mpz_t a, b, c, d;
};

/* 
 * This module provides access to the operations on the specified group
 * and is absolutly free of any cryptographic devices. This is math :-).
 */

#define OAKLEY_GRP_1	1
#define OAKLEY_GRP_2	2
#define OAKLEY_GRP_3	3
#define OAKLEY_GRP_4	4

/* Describe preconfigured MODP groups */

/*
 * The Generalized Number Field Sieve has an asymptotic running time
 * of: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))), where q is the
 * group order, e.g. q = 2**768.
 */

struct modp_dscr oakley_modp[] =
{
  { OAKLEY_GRP_1, 72,	/* This group is insecure, only sufficient for DES */
    "0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1"
    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD"
    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245"
    "E485B576625E7EC6F44C42E9A63A3620FFFFFFFFFFFFFFFF",
    "0x02"
  },
  { OAKLEY_GRP_2, 82,	/* This group is a bit better */
    "0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1"
    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD"
    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245"
    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED"
    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381"
    "FFFFFFFFFFFFFFFF",
    "0x02"
  }
};

/* Describe preconfigured EC2N groups */

/*
 * Related collision-search methods can compute discrete logarithmns
 * in O(sqrt(r)), r being the subgroup order.
 */

struct ec2n_dscr oakley_ec2n[] = {
  { OAKLEY_GRP_3, 76,	/* This group is also considered insecure (P1363) */
    "0x0800000000000000000000004000000000000001", 
    "0x7b",
    "0x00",
    "0x7338f" },
  { OAKLEY_GRP_4, 91, 
    "0x020000000000000000000000000000200000000000000001",
    "0x18",
    "0x00",
    "0x1ee9" },
};

struct group groups[] = {
  {
    MODP, OAKLEY_GRP_1, 0, &oakley_modp[0], NULL, NULL, NULL, NULL, NULL,
    (int (*) (struct group *))modp_getlen,
    (void (*) (struct group *, void *, u_int8_t *))modp_getraw,
    (void (*) (struct group *, void *, u_int8_t *, int))modp_setraw,
    (void (*) (struct group *, void *))modp_setrandom,
    (void (*) (struct group *, void *, void *, void *))modp_operation
  },
  {
    MODP, OAKLEY_GRP_2, 0, &oakley_modp[1], NULL, NULL, NULL, NULL, NULL,
    (int (*) (struct group *))modp_getlen,
    (void (*) (struct group *, void *, u_int8_t *))modp_getraw,
    (void (*) (struct group *, void *, u_int8_t *, int))modp_setraw,
    (void (*) (struct group *, void *))modp_setrandom,
    (void (*) (struct group *, void *, void *, void *))modp_operation
  },
  {
    EC2N, OAKLEY_GRP_3, 0, &oakley_ec2n[0], NULL, NULL, NULL, NULL, NULL,
    (int (*) (struct group *))ec2n_getlen,
    (void (*) (struct group *, void *, u_int8_t *))ec2n_getraw,
    (void (*) (struct group *, void *, u_int8_t *, int))ec2n_setraw,
    (void (*) (struct group *, void *))ec2n_setrandom,
    (void (*) (struct group *, void *, void *, void *))ec2n_operation
  },
  {
    EC2N, OAKLEY_GRP_4, 0, &oakley_ec2n[1], NULL, NULL, NULL, NULL, NULL,
    (int (*) (struct group *))ec2n_getlen,
    (void (*) (struct group *, void *, u_int8_t *))ec2n_getraw,
    (void (*) (struct group *, void *, u_int8_t *, int))ec2n_setraw,
    (void (*) (struct group *, void *))ec2n_setrandom,
    (void (*) (struct group *, void *, void *, void *))ec2n_operation
  }
};


/*
 * Initalize the group structure for later use,
 * this is done by converting the values given in the describtion
 * and converting them to their native representation.
 */ 

void
group_init (void)
{
  int i;

  for (i = sizeof (groups)/sizeof (groups[0]) -1; i >= 0; i--)
    switch (groups[i].type)
      {
      case EC2N:		/* Initalize an Elliptic Curve over GF(2**n) */
	ec2n_init (&groups[i]);
	break;

      case MODP:		/* Initalize an over GF(p) */
	modp_init (&groups[i]);
	break;
	
      default:
	log_print ("Unknown group type %d at index %d in group_init().", 
		   groups[i].type, i);
	break;
      }
}

struct group *
group_get (int id)
{
  struct group *new, *clone;
  if (id < 1 || id > (sizeof (groups)/sizeof (groups[0])))
    return NULL;

  clone = &groups[id-1];

  if ((new = malloc (sizeof (struct group))) == NULL)
    {
      log_print ("group_get: Out of memory");
      return (NULL);
    }

  switch (clone->type)
    {
    case EC2N:
      new = ec2n_clone (new, clone);
      break;
    case MODP:
      new = modp_clone (new, clone);
      break;
    default:
      log_print ("group_get: Unknown group type %d", clone->type);
      free (new);
      return (NULL);
    }
  return (new);
}

void
group_free (struct group *grp)
{
  switch (grp->type)
    {
    case EC2N:
      ec2n_free (grp);
      break;
    case MODP:
      modp_free (grp);
    default:
      log_print ("group_free: Unknown group type %d", grp->type);
      break;
    }
  free (grp);
}

struct group *
modp_clone (struct group *new, struct group *clone)
{
  struct modp_group *new_grp, *clone_grp = clone->group;

  if ((new_grp = malloc (sizeof (struct modp_group))) == NULL)
    {
      log_print ("modp_clone: Out of memory");
      free (new);
      return (NULL);
    }

  memcpy (new, clone, sizeof (struct group));

  new->group = new_grp;
  mpz_init_set (new_grp->p, clone_grp->p);

  mpz_init_set (new_grp->gen, clone_grp->gen);

  mpz_init (new_grp->a);
  mpz_init (new_grp->b);
  mpz_init (new_grp->c);

  new->gen = new_grp->gen;
  new->a = new_grp->a;
  new->b = new_grp->b;
  new->c = new_grp->c;

  return (new);
}

void
modp_free (struct group *old)
{
  struct modp_group *grp = old->group;

  mpz_clear (grp->p);
  mpz_clear (grp->gen); 
  mpz_clear (grp->a);
  mpz_clear (grp->b);
  mpz_clear (grp->c);

  free (grp);
}

void
modp_init (struct group *group)
{
  struct modp_dscr *dscr = (struct modp_dscr *)group->group;

  struct modp_group *grp;

  if ((grp = malloc (sizeof (struct modp_group))) == NULL)
      log_fatal ("modp_init: Out of memory");

  group->bits = dscr->bits;

  mpz_init_set_str (grp->p, dscr->prime, 0);

  mpz_init_set_str (grp->gen, dscr->gen, 0);

  mpz_init (grp->a);
  mpz_init (grp->b);
  mpz_init (grp->c);

  group->gen = grp->gen;
  group->a = grp->a;
  group->b = grp->b;
  group->c = grp->c;

  group->group = grp;
}

struct group *
ec2n_clone (struct group *new, struct group *clone)
{
  struct ec2n_group *new_grp, *clone_grp = clone->group;

  if ((new_grp = malloc (sizeof (struct ec2n_group))) == NULL)
    {
      log_print ("ec2n_clone: Out of memory");
      free (new);
      return (NULL);
    }

  memcpy (new, clone, sizeof (struct group));

  new->group = new_grp;
  ec2ng_init (new_grp->grp);
  ec2ng_set (new_grp->grp, clone_grp->grp);

  ec2np_init (new_grp->gen); 
  ec2np_set (new_grp->gen, clone_grp->gen);

  ec2np_init (new_grp->a);
  ec2np_init (new_grp->b);
  ec2np_init (new_grp->c);

  new->gen = new_grp->gen;
  new->a = new_grp->a;
  new->b = new_grp->b;
  new->c = new_grp->c;
  new->d = ((ec2np_ptr)new->a)->x;

  return (new);
}

void
ec2n_free (struct group *old)
{
  struct ec2n_group *grp = old->group;

  ec2ng_clear (grp->grp);
  ec2np_clear (grp->gen); 
  ec2np_clear (grp->a);
  ec2np_clear (grp->b);
  ec2np_clear (grp->c);

  free (grp);
}

void
ec2n_init (struct group *group)
{
  struct ec2n_dscr *dscr = (struct ec2n_dscr *)group->group;

  struct ec2n_group *grp;

  if ((grp = malloc (sizeof (struct ec2n_group))) == NULL)
      log_fatal ("ec2n_init: Out of memory");

  group->bits = dscr->bits;

  ec2ng_init (grp->grp);
  ec2ng_set_p_str (grp->grp, dscr->polynomial);
  grp->grp->p->bits = b2n_sigbit (grp->grp->p);
  ec2ng_set_a_str (grp->grp, dscr->a);
  ec2ng_set_b_str (grp->grp, dscr->b);

  ec2np_init (grp->gen); ec2np_set_x_str (grp->gen, dscr->gen_x);
  ec2np_find_y (grp->gen, grp->grp);

  /* Sanity check */
  if (!ec2np_ison (grp->gen, grp->grp))
    log_fatal ("ec2n_init: Generator is not on curve");

  ec2np_init (grp->a);
  ec2np_init (grp->b);
  ec2np_init (grp->c);

  group->gen = grp->gen;
  group->a = grp->a;
  group->b = grp->b;
  group->c = grp->c;
  group->d = ((ec2np_ptr)group->a)->x;

  group->group = grp;
}

int 
modp_getlen (struct group *group)
{
  struct modp_group *grp = (struct modp_group *)group->group;

  return mpz_sizeinoctets (grp->p);
}

void 
modp_getraw (struct group *grp, mpz_ptr v, u_int8_t *d)
{
  mpz_getraw (d, v, grp->getlen (grp));
}

void 
modp_setraw (struct group *grp, mpz_ptr d, u_int8_t *s, int l)
{
  mpz_setraw (d, s, l);
}

void 
modp_setrandom (struct group *grp, mpz_ptr d)
{
  int i, l = grp->getlen (grp);
  u_int32_t tmp = 0;

  mpz_set_ui (d, 0);

  for (i = 0; i < l; i++)
    {
      if (i % 4)
	tmp = sysdep_random();

      mpz_mul_2exp (d, d, 8);
      mpz_add_ui (d, d, tmp & 0xFF);
      tmp >>= 8;
    }
}

void 
modp_operation (struct group *group, mpz_ptr d, mpz_ptr a, mpz_ptr e)
{
  struct modp_group *grp = (struct modp_group *)group->group;
  mpz_powm (d, a, e, grp->p);
}

int 
ec2n_getlen (struct group *group)
{
  struct ec2n_group *grp = (struct ec2n_group *)group->group;
  int bits = b2n_sigbit (grp->grp->p) - 1;

  return (7 + bits) >> 3;
}

void 
ec2n_getraw (struct group *group, ec2np_ptr xo, u_int8_t *e)
{
  struct ec2n_group *grp = (struct ec2n_group *)group->group;
  int chunks, bytes, i, j;
  b2n_ptr x = xo->x;
  CHUNK_TYPE tmp;

  bytes = b2n_sigbit (grp->grp->p) - 1;
  chunks = (CHUNK_MASK + bytes) >> CHUNK_SHIFTS;
  bytes = ((7 + (bytes & CHUNK_MASK)) >> 3);

  for (i = chunks-1; i >= 0; i--)
    {
      tmp = (i >= x->chunks ? 0 : x->limp[i]);
      for (j = (i == chunks - 1 ? bytes : CHUNK_BYTES) - 1; j >= 0; j--)
	{
	  e[j] = tmp & 0xFF;
	  tmp >>= 8;
	}
      e += (i == chunks - 1 ? bytes : CHUNK_BYTES);
    }
}

void 
ec2n_setraw (struct group *grp, ec2np_ptr out, u_int8_t *s, int l)
{
  int len, bytes, i, j;
  b2n_ptr outx = out->x;
  CHUNK_TYPE tmp;

  len = (CHUNK_BYTES - 1 + l)/CHUNK_BYTES;
  b2n_resize (outx, len);

  bytes = ((l - 1) % CHUNK_BYTES) + 1;

  for (i = len - 1; i >= 0; i--)
    {
      tmp = 0;
      for (j = (i == len - 1 ? bytes : CHUNK_BYTES); j > 0; j--)
	{
	  tmp <<= 8;
	  tmp |= *s++;
	}
      outx->limp[i] = tmp;
    }
}

void 
ec2n_setrandom (struct group *group, ec2np_ptr x)
{
  b2n_ptr d = x->x;
  struct ec2n_group *grp = (struct ec2n_group *)group->group;
  b2n_random (d, b2n_sigbit (grp->grp->p) - 1);
}

/*
 * This is an attempt at operation abstraction. It can happen
 * that we need to initalize the y variable for the operation
 * to proceed correctly. When this is the case operation has
 * to supply the variable 'a' with the chunks of the Y cooridnate
 * set to zero.
 */

void 
ec2n_operation (struct group *grp, ec2np_ptr d, ec2np_ptr a, ec2np_ptr e)
{
  b2n_ptr ex = e->x;
  struct ec2n_group *group = (struct ec2n_group *)grp->group;

  if (a->y->chunks == 0)
    ec2np_find_y (a, group->grp);

  ec2np_mul (d, a, ex, group->grp);
}