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 | |
51 | static inline MPI mpi_new(unsigned int nbits) |
52 | { |
53 | return mpi_alloc(nlimbs: (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 | */ |
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 | |