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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* mpi.h - Multi Precision Integers
* Copyright (C) 1994, 1996, 1998, 1999,
* 2000, 2001 Free Software Foundation, Inc.
* This file is part of GNUPG.
* 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.
* The GNU MP Library itself is published under the LGPL;
* however I decided to publish this code under the plain GPL.
#ifndef G10_MPI_H
#define G10_MPI_H
#include <linux/types.h>
#include <linux/scatterlist.h>
typedef unsigned long int mpi_limb_t;
typedef signed long int mpi_limb_signed_t;
struct gcry_mpi {
int alloced; /* array size (# of allocated limbs) */
int nlimbs; /* number of valid limbs */
int nbits; /* the real number of valid bits (info only) */
int sign; /* indicates a negative number */
unsigned flags; /* bit 0: array must be allocated in secure memory space */
/* bit 1: not used */
/* bit 2: the limb is a pointer to some m_alloced data */
mpi_limb_t *d; /* array with the limbs */
typedef struct gcry_mpi *MPI;
#define mpi_get_nlimbs(a) ((a)->nlimbs)
#define mpi_has_sign(a) ((a)->sign)
/*-- mpiutil.c --*/
MPI mpi_alloc(unsigned nlimbs);
void mpi_clear(MPI a);
void mpi_free(MPI a);
int mpi_resize(MPI a, unsigned nlimbs);
static inline MPI mpi_new(unsigned int nbits)
return mpi_alloc((nbits + BITS_PER_MPI_LIMB - 1) / BITS_PER_MPI_LIMB);
MPI mpi_copy(MPI a);
MPI mpi_alloc_like(MPI a);
void mpi_snatch(MPI w, MPI u);
MPI mpi_set(MPI w, MPI u);
MPI mpi_set_ui(MPI w, unsigned long u);
MPI mpi_alloc_set_ui(unsigned long u);
void mpi_swap_cond(MPI a, MPI b, unsigned long swap);
/* Constants used to return constant MPIs. See mpi_init if you
* want to add more constants.
enum gcry_mpi_constants {
MPI mpi_const(enum gcry_mpi_constants no);
/*-- mpicoder.c --*/
/* Different formats of external big integer representation. */
enum gcry_mpi_format {
GCRYMPI_FMT_STD = 1, /* Twos complement stored without length. */
GCRYMPI_FMT_PGP = 2, /* As used by OpenPGP (unsigned only). */
GCRYMPI_FMT_SSH = 3, /* As used by SSH (like STD but with length). */
GCRYMPI_FMT_HEX = 4, /* Hex format. */
GCRYMPI_FMT_USG = 5, /* Like STD but unsigned. */
GCRYMPI_FMT_OPAQUE = 8 /* Opaque format (some functions only). */
MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
int mpi_fromstr(MPI val, const char *str);
MPI mpi_scanval(const char *string);
MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign);
int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
int *sign);
int mpi_write_to_sgl(MPI a, struct scatterlist *sg, unsigned nbytes,
int *sign);
int mpi_print(enum gcry_mpi_format format, unsigned char *buffer,
size_t buflen, size_t *nwritten, MPI a);
/*-- mpi-mod.c --*/
void mpi_mod(MPI rem, MPI dividend, MPI divisor);
/* Context used with Barrett reduction. */
struct barrett_ctx_s;
typedef struct barrett_ctx_s *mpi_barrett_t;
mpi_barrett_t mpi_barrett_init(MPI m, int copy);
void mpi_barrett_free(mpi_barrett_t ctx);
void mpi_mod_barrett(MPI r, MPI x, mpi_barrett_t ctx);
void mpi_mul_barrett(MPI w, MPI u, MPI v, mpi_barrett_t ctx);
/*-- mpi-pow.c --*/
int mpi_powm(MPI res, MPI base, MPI exp, MPI mod);
/*-- mpi-cmp.c --*/
int mpi_cmp_ui(MPI u, ulong v);
int mpi_cmp(MPI u, MPI v);
int mpi_cmpabs(MPI u, MPI v);
/*-- mpi-sub-ui.c --*/
int mpi_sub_ui(MPI w, MPI u, unsigned long vval);
/*-- mpi-bit.c --*/
void mpi_normalize(MPI a);
unsigned mpi_get_nbits(MPI a);
int mpi_test_bit(MPI a, unsigned int n);
void mpi_set_bit(MPI a, unsigned int n);
void mpi_set_highbit(MPI a, unsigned int n);
void mpi_clear_highbit(MPI a, unsigned int n);
void mpi_clear_bit(MPI a, unsigned int n);
void mpi_rshift_limbs(MPI a, unsigned int count);
void mpi_rshift(MPI x, MPI a, unsigned int n);
void mpi_lshift_limbs(MPI a, unsigned int count);
void mpi_lshift(MPI x, MPI a, unsigned int n);
/*-- mpi-add.c --*/
void mpi_add_ui(MPI w, MPI u, unsigned long v);
void mpi_add(MPI w, MPI u, MPI v);
void mpi_sub(MPI w, MPI u, MPI v);
void mpi_addm(MPI w, MPI u, MPI v, MPI m);
void mpi_subm(MPI w, MPI u, MPI v, MPI m);
/*-- mpi-mul.c --*/
void mpi_mul(MPI w, MPI u, MPI v);
void mpi_mulm(MPI w, MPI u, MPI v, MPI m);
/*-- mpi-div.c --*/
void mpi_tdiv_r(MPI rem, MPI num, MPI den);
void mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor);
void mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor);
/*-- mpi-inv.c --*/
int mpi_invm(MPI x, MPI a, MPI n);
/*-- ec.c --*/
/* Object to represent a point in projective coordinates */
struct gcry_mpi_point {
MPI x;
MPI y;
MPI z;
typedef struct gcry_mpi_point *MPI_POINT;
/* Models describing an elliptic curve */
enum gcry_mpi_ec_models {
/* The Short Weierstrass equation is
* y^2 = x^3 + ax + b
/* The Montgomery equation is
* by^2 = x^3 + ax^2 + x
/* The Twisted Edwards equation is
* ax^2 + y^2 = 1 + bx^2y^2
* Note that we use 'b' instead of the commonly used 'd'.
/* Dialects used with elliptic curves */
enum ecc_dialects {
/* This context is used with all our EC functions. */
struct mpi_ec_ctx {
enum gcry_mpi_ec_models model; /* The model describing this curve. */
enum ecc_dialects dialect; /* The ECC dialect used with the curve. */
int flags; /* Public key flags (not always used). */
unsigned int nbits; /* Number of bits. */
/* Domain parameters. Note that they may not all be set and if set
* the MPIs may be flagged as constant.
MPI p; /* Prime specifying the field GF(p). */
MPI a; /* First coefficient of the Weierstrass equation. */
MPI b; /* Second coefficient of the Weierstrass equation. */
MPI_POINT G; /* Base point (generator). */
MPI n; /* Order of G. */
unsigned int h; /* Cofactor. */
/* The actual key. May not be set. */
MPI_POINT Q; /* Public key. */
MPI d; /* Private key. */
const char *name; /* Name of the curve. */
/* This structure is private to mpi/ec.c! */
struct {
struct {
unsigned int a_is_pminus3:1;
unsigned int two_inv_p:1;
} valid; /* Flags to help setting the helper vars below. */
int a_is_pminus3; /* True if A = P - 3. */
MPI two_inv_p;
mpi_barrett_t p_barrett;
/* Scratch variables. */
MPI scratch[11];
/* Helper for fast reduction. */
/* int nist_nbits; /\* If this is a NIST curve, the # of bits. *\/ */
/* MPI s[10]; */
/* MPI c; */
} t;
/* Curve specific computation routines for the field. */
void (*addm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ctx);
void (*subm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ec);
void (*mulm)(MPI w, MPI u, MPI v, struct mpi_ec_ctx *ctx);
void (*pow2)(MPI w, const MPI b, struct mpi_ec_ctx *ctx);
void (*mul2)(MPI w, MPI u, struct mpi_ec_ctx *ctx);
void mpi_ec_init(struct mpi_ec_ctx *ctx, enum gcry_mpi_ec_models model,
enum ecc_dialects dialect,
int flags, MPI p, MPI a, MPI b);
void mpi_ec_deinit(struct mpi_ec_ctx *ctx);
MPI_POINT mpi_point_new(unsigned int nbits);
void mpi_point_release(MPI_POINT p);
void mpi_point_init(MPI_POINT p);
void mpi_point_free_parts(MPI_POINT p);
int mpi_ec_get_affine(MPI x, MPI y, MPI_POINT point, struct mpi_ec_ctx *ctx);
void mpi_ec_add_points(MPI_POINT result,
struct mpi_ec_ctx *ctx);
void mpi_ec_mul_point(MPI_POINT result,
MPI scalar, MPI_POINT point,
struct mpi_ec_ctx *ctx);
int mpi_ec_curve_point(MPI_POINT point, struct mpi_ec_ctx *ctx);
/* inline functions */
* mpi_get_size() - returns max size required to store the number
* @a: A multi precision integer for which we want to allocate a buffer
* Return: size required to store the number
static inline unsigned int mpi_get_size(MPI a)
return a->nlimbs * BYTES_PER_MPI_LIMB;
#endif /*G10_MPI_H */