aboutsummaryrefslogtreecommitdiff
path: root/include/linux/mpi.h
blob: eb0d1c1db208eb8d06c62a26b38954d9e3d55286 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/* 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>

#define BYTES_PER_MPI_LIMB	(BITS_PER_LONG / 8)
#define BITS_PER_MPI_LIMB	BITS_PER_LONG

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.
 */
#define MPI_NUMBER_OF_CONSTANTS 6
enum gcry_mpi_constants {
	MPI_C_ZERO,
	MPI_C_ONE,
	MPI_C_TWO,
	MPI_C_THREE,
	MPI_C_FOUR,
	MPI_C_EIGHT
};

MPI mpi_const(enum gcry_mpi_constants no);

/*-- mpicoder.c --*/

/* Different formats of external big integer representation. */
enum gcry_mpi_format {
	GCRYMPI_FMT_NONE = 0,
	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
	 */
	MPI_EC_WEIERSTRASS = 0,
	/* The Montgomery equation is
	 *      by^2 = x^3 + ax^2 + x
	 */
	MPI_EC_MONTGOMERY,
	/* The Twisted Edwards equation is
	 *      ax^2 + y^2 = 1 + bx^2y^2
	 * Note that we use 'b' instead of the commonly used 'd'.
	 */
	MPI_EC_EDWARDS
};

/* Dialects used with elliptic curves */
enum ecc_dialects {
	ECC_DIALECT_STANDARD = 0,
	ECC_DIALECT_ED25519,
	ECC_DIALECT_SAFECURVE
};

/* 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,
			MPI_POINT p1, MPI_POINT p2,
			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 */