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
26 typedef unsigned long int mpi_limb_t;
27 typedef signed long int mpi_limb_signed_t;
28
29 struct 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
40 typedef 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 --*/
46 MPI mpi_alloc(unsigned nlimbs);
47 void mpi_clear(MPI a);
48 void mpi_free(MPI a);
49 int mpi_resize(MPI a, unsigned nlimbs);
50
mpi_new(unsigned int nbits)51 static inline MPI mpi_new(unsigned int nbits)
52 {
53 return mpi_alloc((nbits + BITS_PER_MPI_LIMB - 1) / BITS_PER_MPI_LIMB);
54 }
55
56 MPI mpi_copy(MPI a);
57 MPI mpi_alloc_like(MPI a);
58 void mpi_snatch(MPI w, MPI u);
59 MPI mpi_set(MPI w, MPI u);
60 MPI mpi_set_ui(MPI w, unsigned long u);
61 MPI mpi_alloc_set_ui(unsigned long u);
62 void 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
68 enum 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
77 MPI mpi_const(enum gcry_mpi_constants no);
78
79 /*-- mpicoder.c --*/
80
81 /* Different formats of external big integer representation. */
82 enum 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
92 MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
93 MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
94 int mpi_fromstr(MPI val, const char *str);
95 MPI mpi_scanval(const char *string);
96 MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
97 void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign);
98 int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
99 int *sign);
100 int mpi_write_to_sgl(MPI a, struct scatterlist *sg, unsigned nbytes,
101 int *sign);
102 int mpi_print(enum gcry_mpi_format format, unsigned char *buffer,
103 size_t buflen, size_t *nwritten, MPI a);
104
105 /*-- mpi-mod.c --*/
106 void mpi_mod(MPI rem, MPI dividend, MPI divisor);
107
108 /* Context used with Barrett reduction. */
109 struct barrett_ctx_s;
110 typedef struct barrett_ctx_s *mpi_barrett_t;
111
112 mpi_barrett_t mpi_barrett_init(MPI m, int copy);
113 void mpi_barrett_free(mpi_barrett_t ctx);
114 void mpi_mod_barrett(MPI r, MPI x, mpi_barrett_t ctx);
115 void mpi_mul_barrett(MPI w, MPI u, MPI v, mpi_barrett_t ctx);
116
117 /*-- mpi-pow.c --*/
118 int mpi_powm(MPI res, MPI base, MPI exp, MPI mod);
119
120 /*-- mpi-cmp.c --*/
121 int mpi_cmp_ui(MPI u, ulong v);
122 int mpi_cmp(MPI u, MPI v);
123 int mpi_cmpabs(MPI u, MPI v);
124
125 /*-- mpi-sub-ui.c --*/
126 int mpi_sub_ui(MPI w, MPI u, unsigned long vval);
127
128 /*-- mpi-bit.c --*/
129 void mpi_normalize(MPI a);
130 unsigned mpi_get_nbits(MPI a);
131 int mpi_test_bit(MPI a, unsigned int n);
132 void mpi_set_bit(MPI a, unsigned int n);
133 void mpi_set_highbit(MPI a, unsigned int n);
134 void mpi_clear_highbit(MPI a, unsigned int n);
135 void mpi_clear_bit(MPI a, unsigned int n);
136 void mpi_rshift_limbs(MPI a, unsigned int count);
137 void mpi_rshift(MPI x, MPI a, unsigned int n);
138 void mpi_lshift_limbs(MPI a, unsigned int count);
139 void mpi_lshift(MPI x, MPI a, unsigned int n);
140
141 /*-- mpi-add.c --*/
142 void mpi_add_ui(MPI w, MPI u, unsigned long v);
143 void mpi_add(MPI w, MPI u, MPI v);
144 void mpi_sub(MPI w, MPI u, MPI v);
145 void mpi_addm(MPI w, MPI u, MPI v, MPI m);
146 void mpi_subm(MPI w, MPI u, MPI v, MPI m);
147
148 /*-- mpi-mul.c --*/
149 void mpi_mul(MPI w, MPI u, MPI v);
150 void mpi_mulm(MPI w, MPI u, MPI v, MPI m);
151
152 /*-- mpi-div.c --*/
153 void mpi_tdiv_r(MPI rem, MPI num, MPI den);
154 void mpi_fdiv_r(MPI rem, MPI dividend, MPI divisor);
155 void mpi_fdiv_q(MPI quot, MPI dividend, MPI divisor);
156
157 /*-- mpi-inv.c --*/
158 int mpi_invm(MPI x, MPI a, MPI n);
159
160 /*-- ec.c --*/
161
162 /* Object to represent a point in projective coordinates */
163 struct gcry_mpi_point {
164 MPI x;
165 MPI y;
166 MPI z;
167 };
168
169 typedef struct gcry_mpi_point *MPI_POINT;
170
171 /* Models describing an elliptic curve */
172 enum 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 */
189 enum 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. */
196 struct 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
248 void 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);
251 void mpi_ec_deinit(struct mpi_ec_ctx *ctx);
252 MPI_POINT mpi_point_new(unsigned int nbits);
253 void mpi_point_release(MPI_POINT p);
254 void mpi_point_init(MPI_POINT p);
255 void mpi_point_free_parts(MPI_POINT p);
256 int mpi_ec_get_affine(MPI x, MPI y, MPI_POINT point, struct mpi_ec_ctx *ctx);
257 void mpi_ec_add_points(MPI_POINT result,
258 MPI_POINT p1, MPI_POINT p2,
259 struct mpi_ec_ctx *ctx);
260 void mpi_ec_mul_point(MPI_POINT result,
261 MPI scalar, MPI_POINT point,
262 struct mpi_ec_ctx *ctx);
263 int 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 */
mpi_get_size(MPI a)274 static inline unsigned int mpi_get_size(MPI a)
275 {
276 return a->nlimbs * BYTES_PER_MPI_LIMB;
277 }
278 #endif /*G10_MPI_H */
279