LXR linux/include/linux/mpi.h

   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2/* mpi.h  -  Multi Precision Integers
   3 *      Copyright (C) 1994, 1996, 1998, 1999,
   4 *                    2000, 2001 Free Software Foundation, Inc.
   5 *
   6 * This file is part of GNUPG.
   7 *
   8 * Note: This code is heavily based on the GNU MP Library.
   9 *       Actually it's the same code with only minor changes in the
  10 *       way the data is stored; this is to support the abstraction
  11 *       of an optional secure memory allocation which may be used
  12 *       to avoid revealing of sensitive data due to paging etc.
  13 *       The GNU MP Library itself is published under the LGPL;
  14 *       however I decided to publish this code under the plain GPL.
  15 */
  16
  17#ifndef G10_MPI_H
  18#define G10_MPI_H
  19
  20#include <linux/types.h>
  21#include <linux/scatterlist.h>
  22
  23#define BYTES_PER_MPI_LIMB      (BITS_PER_LONG / 8)
  24#define BITS_PER_MPI_LIMB       BITS_PER_LONG
  25
  26typedef unsigned long int mpi_limb_t;
  27typedef signed long int mpi_limb_signed_t;
  28
  29struct gcry_mpi {
  30        int alloced;            /* array size (# of allocated limbs) */
  31        int nlimbs;             /* number of valid limbs */
  32        int nbits;              /* the real number of valid bits (info only) */
  33        int sign;               /* indicates a negative number */
  34        unsigned flags;         /* bit 0: array must be allocated in secure memory space */
  35        /* bit 1: not used */
  36        /* bit 2: the limb is a pointer to some m_alloced data */
  37        mpi_limb_t *d;          /* array with the limbs */
  38};
  39
  40typedef struct gcry_mpi *MPI;
  41
  42#define mpi_get_nlimbs(a)     ((a)->nlimbs)
  43#define mpi_has_sign(a)       ((a)->sign)
  44
  45/*-- mpiutil.c --*/
  46MPI mpi_alloc(unsigned nlimbs);
  47void mpi_clear(MPI a);
  48void mpi_free(MPI a);
  49int mpi_resize(MPI a, unsigned nlimbs);
  50
  51static inline MPI mpi_new(unsigned int nbits)
  52{
  53        return mpi_alloc((nbits + BITS_PER_MPI_LIMB - 1) / BITS_PER_MPI_LIMB);
  54}
  55
  56MPI mpi_copy(MPI a);
  57MPI mpi_alloc_like(MPI a);
  58void mpi_snatch(MPI w, MPI u);
  59MPI mpi_set(MPI w, MPI u);
  60MPI mpi_set_ui(MPI w, unsigned long u);
  61MPI mpi_alloc_set_ui(unsigned long u);
  62void mpi_swap_cond(MPI a, MPI b, unsigned long swap);
  63
  64/* Constants used to return constant MPIs.  See mpi_init if you
  65 * want to add more constants.
  66 */
  67#define MPI_NUMBER_OF_CONSTANTS 6
  68enum gcry_mpi_constants {
  69        MPI_C_ZERO,
  70        MPI_C_ONE,
  71        MPI_C_TWO,
  72        MPI_C_THREE,
  73        MPI_C_FOUR,
  74        MPI_C_EIGHT
  75};
  76
  77MPI mpi_const(enum gcry_mpi_constants no);
  78
  79/*-- mpicoder.c --*/
  80
  81/* Different formats of external big integer representation. */
  82enum gcry_mpi_format {
  83        GCRYMPI_FMT_NONE = 0,
  84        GCRYMPI_FMT_STD = 1,    /* Twos complement stored without length. */
  85        GCRYMPI_FMT_PGP = 2,    /* As used by OpenPGP (unsigned only). */
  86        GCRYMPI_FMT_SSH = 3,    /* As used by SSH (like STD but with length). */
  87        GCRYMPI_FMT_HEX = 4,    /* Hex format. */
  88        GCRYMPI_FMT_USG = 5,    /* Like STD but unsigned. */
  89        GCRYMPI_FMT_OPAQUE = 8  /* Opaque format (some functions only). */
  90};
  91
  92MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
  93MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
  94int mpi_fromstr(MPI val, const char *str);
  95MPI mpi_scanval(const char *string);
  96MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
  97void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign);
  98int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
  99                    int *sign);
 100int mpi_write_to_sgl(MPI a, struct scatterlist *sg, unsigned nbytes,
 101                     int *sign);
 102int mpi_print(enum gcry_mpi_format format, unsigned char *buffer,
 103                        size_t buflen, size_t *nwritten, MPI a);
 104
 105/*-- mpi-mod.c --*/
 106void mpi_mod(MPI rem, MPI dividend, MPI divisor);
 107
 108/* Context used with Barrett reduction.  */
 109struct barrett_ctx_s;
 110typedef struct barrett_ctx_s *mpi_barrett_t;
 111
 112mpi_barrett_t mpi_barrett_init(MPI m, int copy);
 113void mpi_barrett_free(mpi_barrett_t ctx);
 114void mpi_mod_barrett(MPI r, MPI x, mpi_barrett_t ctx);
 115void mpi_mul_barrett(MPI w, MPI u, MPI v, mpi_barrett_t ctx);
 116
 117/*-- mpi-pow.c --*/
 118int mpi_powm(MPI res, MPI base, MPI exp, MPI mod);
 119
 120/*-- mpi-cmp.c --*/
 121int mpi_cmp_ui(MPI u, ulong v);
 122int mpi_cmp(MPI u, MPI v);
 123int mpi_cmpabs(MPI u, MPI v);
 124
 125/*-- mpi-sub-ui.c --*/
 126int mpi_sub_ui(MPI w, MPI u, unsigned long vval);
 127
 128/*-- mpi-bit.c --*/
 129void mpi_normalize(MPI a);
 130unsigned mpi_get_nbits(MPI a);
 131int mpi_test_bit(MPI a, unsigned int n);
 132void mpi_set_bit(MPI a, unsigned int n);
 133void mpi_set_highbit(MPI a, unsigned int n);
 134void mpi_clear_highbit(MPI a, unsigned int n);
 135void mpi_clear_bit(MPI a, unsigned int n);
 136void mpi_rshift_limbs(MPI a, unsigned int count);
 137void mpi_rshift(MPI x, MPI a, unsigned int n);
 138void mpi_lshift_limbs(MPI a, unsigned int count);
 139void mpi_lshift(MPI x, MPI a, unsigned int n);
 140
 141/*-- mpi-add.c --*/
 142void mpi_add_ui(MPI w, MPI u, unsigned long v);
 143void mpi_add(MPI w, MPI u, MPI v);
 144void mpi_sub(MPI w, MPI u, MPI v);
 145void mpi_addm(MPI w, MPI u, MPI v, MPI m);
 146void mpi_subm(MPI w, MPI u, MPI v, MPI m);
 147
 148/*-- mpi-mul.c --*/
 149void mpi_mul(MPI w, MPI u, MPI v);
 150void mpi_mulm(MPI w, MPI u, MPI v, MPI m);
 151
 152/*-- mpi-div.c --*/
 153void mpi_tdiv_r(MPI rem, MPI num, MPI den);
 154void mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor);
 155void mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor);
 156
 157/*-- mpi-inv.c --*/
 158int mpi_invm(MPI x, MPI a, MPI n);
 159
 160/*-- ec.c --*/
 161
 162/* Object to represent a point in projective coordinates */
 163struct gcry_mpi_point {
 164        MPI x;
 165        MPI y;
 166        MPI z;
 167};
 168
 169typedef struct gcry_mpi_point *MPI_POINT;
 170
 171/* Models describing an elliptic curve */
 172enum gcry_mpi_ec_models {
 173        /* The Short Weierstrass equation is
 174         *      y^2 = x^3 + ax + b
 175         */
 176        MPI_EC_WEIERSTRASS = 0,
 177        /* The Montgomery equation is
 178         *      by^2 = x^3 + ax^2 + x
 179         */
 180        MPI_EC_MONTGOMERY,
 181        /* The Twisted Edwards equation is
 182         *      ax^2 + y^2 = 1 + bx^2y^2
 183         * Note that we use 'b' instead of the commonly used 'd'.
 184         */
 185        MPI_EC_EDWARDS
 186};
 187
 188/* Dialects used with elliptic curves */
 189enum ecc_dialects {
 190        ECC_DIALECT_STANDARD = 0,
 191        ECC_DIALECT_ED25519,
 192        ECC_DIALECT_SAFECURVE
 193};
 194
 195/* This context is used with all our EC functions. */
 196struct mpi_ec_ctx {
 197        enum gcry_mpi_ec_models model; /* The model describing this curve. */
 198        enum ecc_dialects dialect;     /* The ECC dialect used with the curve. */
 199        int flags;                     /* Public key flags (not always used). */
 200        unsigned int nbits;            /* Number of bits.  */
 201
 202        /* Domain parameters.  Note that they may not all be set and if set
 203         * the MPIs may be flagged as constant.
 204         */
 205        MPI p;         /* Prime specifying the field GF(p).  */
 206        MPI a;         /* First coefficient of the Weierstrass equation.  */
 207        MPI b;         /* Second coefficient of the Weierstrass equation.  */
 208        MPI_POINT G;   /* Base point (generator).  */
 209        MPI n;         /* Order of G.  */
 210        unsigned int h;       /* Cofactor.  */
 211
 212        /* The actual key.  May not be set.  */
 213        MPI_POINT Q;   /* Public key.   */
 214        MPI d;         /* Private key.  */
 215
 216        const char *name;      /* Name of the curve.  */
 217
 218        /* This structure is private to mpi/ec.c! */
 219        struct {
 220                struct {
 221                        unsigned int a_is_pminus3:1;
 222                        unsigned int two_inv_p:1;
 223                } valid; /* Flags to help setting the helper vars below.  */
 224
 225                int a_is_pminus3;  /* True if A = P - 3. */
 226
 227                MPI two_inv_p;
 228
 229                mpi_barrett_t p_barrett;
 230
 231                /* Scratch variables.  */
 232                MPI scratch[11];
 233
 234                /* Helper for fast reduction.  */
 235                /*   int nist_nbits; /\* If this is a NIST curve, the # of bits. *\/ */
 236                /*   MPI s[10]; */
 237                /*   MPI c; */
 238        } t;
 239
 240        /* Curve specific computation routines for the field.  */
 241        void (*addm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ctx);
 242        void (*subm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ec);
 243        void (*mulm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ctx);
 244        void (*pow2)(MPI w, const MPI b, struct mpi_ec_ctx *ctx);
 245        void (*mul2)(MPI w, MPI u, struct mpi_ec_ctx *ctx);
 246};
 247
 248void mpi_ec_init(struct mpi_ec_ctx *ctx, enum gcry_mpi_ec_models model,
 249                        enum ecc_dialects dialect,
 250                        int flags, MPI p, MPI a, MPI b);
 251void mpi_ec_deinit(struct mpi_ec_ctx *ctx);
 252MPI_POINT mpi_point_new(unsigned int nbits);
 253void mpi_point_release(MPI_POINT p);
 254void mpi_point_init(MPI_POINT p);
 255void mpi_point_free_parts(MPI_POINT p);
 256int mpi_ec_get_affine(MPI x, MPI y, MPI_POINT point, struct mpi_ec_ctx *ctx);
 257void mpi_ec_add_points(MPI_POINT result,
 258                        MPI_POINT p1, MPI_POINT p2,
 259                        struct mpi_ec_ctx *ctx);
 260void mpi_ec_mul_point(MPI_POINT result,
 261                        MPI scalar, MPI_POINT point,
 262                        struct mpi_ec_ctx *ctx);
 263int mpi_ec_curve_point(MPI_POINT point, struct mpi_ec_ctx *ctx);
 264
 265/* inline functions */
 266
 267/**
 268 * mpi_get_size() - returns max size required to store the number
 269 *
 270 * @a:  A multi precision integer for which we want to allocate a buffer
 271 *
 272 * Return: size required to store the number
 273 */
 274static inline unsigned int mpi_get_size(MPI a)
 275{
 276        return a->nlimbs * BYTES_PER_MPI_LIMB;
 277}
 278#endif /*G10_MPI_H */
 279