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cdec9cb5 DK |
1 | /* mpicoder.c - Coder for the external representation of MPIs |
2 | * Copyright (C) 1998, 1999 Free Software Foundation, Inc. | |
3 | * | |
4 | * This file is part of GnuPG. | |
5 | * | |
6 | * GnuPG is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * GnuPG is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA | |
19 | */ | |
20 | ||
21 | #include "mpi-internal.h" | |
22 | ||
cdec9cb5 DK |
23 | #define MAX_EXTERN_MPI_BITS 16384 |
24 | ||
cdec9cb5 DK |
25 | MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread) |
26 | { | |
27 | const uint8_t *buffer = xbuffer; | |
28 | int i, j; | |
29 | unsigned nbits, nbytes, nlimbs, nread = 0; | |
30 | mpi_limb_t a; | |
3cccd154 | 31 | MPI val = NULL; |
cdec9cb5 DK |
32 | |
33 | if (*ret_nread < 2) | |
34 | goto leave; | |
35 | nbits = buffer[0] << 8 | buffer[1]; | |
36 | ||
37 | if (nbits > MAX_EXTERN_MPI_BITS) { | |
38 | pr_info("MPI: mpi too large (%u bits)\n", nbits); | |
39 | goto leave; | |
40 | } | |
41 | buffer += 2; | |
42 | nread = 2; | |
43 | ||
44 | nbytes = (nbits + 7) / 8; | |
45 | nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB; | |
46 | val = mpi_alloc(nlimbs); | |
47 | if (!val) | |
3cccd154 | 48 | return NULL; |
cdec9cb5 DK |
49 | i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; |
50 | i %= BYTES_PER_MPI_LIMB; | |
51 | val->nbits = nbits; | |
52 | j = val->nlimbs = nlimbs; | |
53 | val->sign = 0; | |
54 | for (; j > 0; j--) { | |
55 | a = 0; | |
56 | for (; i < BYTES_PER_MPI_LIMB; i++) { | |
57 | if (++nread > *ret_nread) { | |
58 | printk | |
59 | ("MPI: mpi larger than buffer nread=%d ret_nread=%d\n", | |
60 | nread, *ret_nread); | |
61 | goto leave; | |
62 | } | |
63 | a <<= 8; | |
64 | a |= *buffer++; | |
65 | } | |
66 | i = 0; | |
67 | val->d[j - 1] = a; | |
68 | } | |
69 | ||
70 | leave: | |
71 | *ret_nread = nread; | |
72 | return val; | |
73 | } | |
74 | EXPORT_SYMBOL_GPL(mpi_read_from_buffer); | |
75 | ||
76 | /**************** | |
77 | * Make an mpi from a character string. | |
78 | */ | |
79 | int mpi_fromstr(MPI val, const char *str) | |
80 | { | |
81 | int hexmode = 0, sign = 0, prepend_zero = 0, i, j, c, c1, c2; | |
82 | unsigned nbits, nbytes, nlimbs; | |
83 | mpi_limb_t a; | |
84 | ||
85 | if (*str == '-') { | |
86 | sign = 1; | |
87 | str++; | |
88 | } | |
89 | if (*str == '0' && str[1] == 'x') | |
90 | hexmode = 1; | |
91 | else | |
92 | return -EINVAL; /* other bases are not yet supported */ | |
93 | str += 2; | |
94 | ||
95 | nbits = strlen(str) * 4; | |
96 | if (nbits % 8) | |
97 | prepend_zero = 1; | |
98 | nbytes = (nbits + 7) / 8; | |
99 | nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB; | |
100 | if (val->alloced < nlimbs) | |
101 | if (!mpi_resize(val, nlimbs)) | |
102 | return -ENOMEM; | |
103 | i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; | |
104 | i %= BYTES_PER_MPI_LIMB; | |
105 | j = val->nlimbs = nlimbs; | |
106 | val->sign = sign; | |
107 | for (; j > 0; j--) { | |
108 | a = 0; | |
109 | for (; i < BYTES_PER_MPI_LIMB; i++) { | |
110 | if (prepend_zero) { | |
111 | c1 = '0'; | |
112 | prepend_zero = 0; | |
113 | } else | |
114 | c1 = *str++; | |
115 | assert(c1); | |
116 | c2 = *str++; | |
117 | assert(c2); | |
118 | if (c1 >= '0' && c1 <= '9') | |
119 | c = c1 - '0'; | |
120 | else if (c1 >= 'a' && c1 <= 'f') | |
121 | c = c1 - 'a' + 10; | |
122 | else if (c1 >= 'A' && c1 <= 'F') | |
123 | c = c1 - 'A' + 10; | |
124 | else { | |
125 | mpi_clear(val); | |
126 | return 1; | |
127 | } | |
128 | c <<= 4; | |
129 | if (c2 >= '0' && c2 <= '9') | |
130 | c |= c2 - '0'; | |
131 | else if (c2 >= 'a' && c2 <= 'f') | |
132 | c |= c2 - 'a' + 10; | |
133 | else if (c2 >= 'A' && c2 <= 'F') | |
134 | c |= c2 - 'A' + 10; | |
135 | else { | |
136 | mpi_clear(val); | |
137 | return 1; | |
138 | } | |
139 | a <<= 8; | |
140 | a |= c; | |
141 | } | |
142 | i = 0; | |
143 | ||
144 | val->d[j - 1] = a; | |
145 | } | |
146 | ||
147 | return 0; | |
148 | } | |
149 | EXPORT_SYMBOL_GPL(mpi_fromstr); | |
150 | ||
cdec9cb5 DK |
151 | /**************** |
152 | * Return an allocated buffer with the MPI (msb first). | |
153 | * NBYTES receives the length of this buffer. Caller must free the | |
154 | * return string (This function does return a 0 byte buffer with NBYTES | |
155 | * set to zero if the value of A is zero. If sign is not NULL, it will | |
156 | * be set to the sign of the A. | |
157 | */ | |
158 | void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign) | |
159 | { | |
160 | uint8_t *p, *buffer; | |
161 | mpi_limb_t alimb; | |
162 | int i; | |
163 | unsigned int n; | |
164 | ||
165 | if (sign) | |
166 | *sign = a->sign; | |
167 | *nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB; | |
168 | if (!n) | |
169 | n++; /* avoid zero length allocation */ | |
170 | p = buffer = kmalloc(n, GFP_KERNEL); | |
4bf1924c DH |
171 | if (!p) |
172 | return NULL; | |
cdec9cb5 DK |
173 | |
174 | for (i = a->nlimbs - 1; i >= 0; i--) { | |
175 | alimb = a->d[i]; | |
176 | #if BYTES_PER_MPI_LIMB == 4 | |
177 | *p++ = alimb >> 24; | |
178 | *p++ = alimb >> 16; | |
179 | *p++ = alimb >> 8; | |
180 | *p++ = alimb; | |
181 | #elif BYTES_PER_MPI_LIMB == 8 | |
182 | *p++ = alimb >> 56; | |
183 | *p++ = alimb >> 48; | |
184 | *p++ = alimb >> 40; | |
185 | *p++ = alimb >> 32; | |
186 | *p++ = alimb >> 24; | |
187 | *p++ = alimb >> 16; | |
188 | *p++ = alimb >> 8; | |
189 | *p++ = alimb; | |
190 | #else | |
191 | #error please implement for this limb size. | |
192 | #endif | |
193 | } | |
194 | ||
195 | /* this is sub-optimal but we need to do the shift operation | |
196 | * because the caller has to free the returned buffer */ | |
197 | for (p = buffer; !*p && *nbytes; p++, --*nbytes) | |
198 | ; | |
199 | if (p != buffer) | |
200 | memmove(buffer, p, *nbytes); | |
201 | ||
202 | return buffer; | |
203 | } | |
204 | EXPORT_SYMBOL_GPL(mpi_get_buffer); | |
205 | ||
206 | /**************** | |
207 | * Use BUFFER to update MPI. | |
208 | */ | |
209 | int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign) | |
210 | { | |
211 | const uint8_t *buffer = xbuffer, *p; | |
212 | mpi_limb_t alimb; | |
213 | int nlimbs; | |
214 | int i; | |
215 | ||
216 | nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB; | |
217 | if (RESIZE_IF_NEEDED(a, nlimbs) < 0) | |
218 | return -ENOMEM; | |
219 | a->sign = sign; | |
220 | ||
221 | for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) { | |
222 | #if BYTES_PER_MPI_LIMB == 4 | |
223 | alimb = (mpi_limb_t) *p--; | |
224 | alimb |= (mpi_limb_t) *p-- << 8; | |
225 | alimb |= (mpi_limb_t) *p-- << 16; | |
226 | alimb |= (mpi_limb_t) *p-- << 24; | |
227 | #elif BYTES_PER_MPI_LIMB == 8 | |
228 | alimb = (mpi_limb_t) *p--; | |
229 | alimb |= (mpi_limb_t) *p-- << 8; | |
230 | alimb |= (mpi_limb_t) *p-- << 16; | |
231 | alimb |= (mpi_limb_t) *p-- << 24; | |
232 | alimb |= (mpi_limb_t) *p-- << 32; | |
233 | alimb |= (mpi_limb_t) *p-- << 40; | |
234 | alimb |= (mpi_limb_t) *p-- << 48; | |
235 | alimb |= (mpi_limb_t) *p-- << 56; | |
236 | #else | |
237 | #error please implement for this limb size. | |
238 | #endif | |
239 | a->d[i++] = alimb; | |
240 | } | |
241 | if (p >= buffer) { | |
242 | #if BYTES_PER_MPI_LIMB == 4 | |
243 | alimb = *p--; | |
244 | if (p >= buffer) | |
245 | alimb |= (mpi_limb_t) *p-- << 8; | |
246 | if (p >= buffer) | |
247 | alimb |= (mpi_limb_t) *p-- << 16; | |
248 | if (p >= buffer) | |
249 | alimb |= (mpi_limb_t) *p-- << 24; | |
250 | #elif BYTES_PER_MPI_LIMB == 8 | |
251 | alimb = (mpi_limb_t) *p--; | |
252 | if (p >= buffer) | |
253 | alimb |= (mpi_limb_t) *p-- << 8; | |
254 | if (p >= buffer) | |
255 | alimb |= (mpi_limb_t) *p-- << 16; | |
256 | if (p >= buffer) | |
257 | alimb |= (mpi_limb_t) *p-- << 24; | |
258 | if (p >= buffer) | |
259 | alimb |= (mpi_limb_t) *p-- << 32; | |
260 | if (p >= buffer) | |
261 | alimb |= (mpi_limb_t) *p-- << 40; | |
262 | if (p >= buffer) | |
263 | alimb |= (mpi_limb_t) *p-- << 48; | |
264 | if (p >= buffer) | |
265 | alimb |= (mpi_limb_t) *p-- << 56; | |
266 | #else | |
267 | #error please implement for this limb size. | |
268 | #endif | |
269 | a->d[i++] = alimb; | |
270 | } | |
271 | a->nlimbs = i; | |
272 | ||
273 | if (i != nlimbs) { | |
274 | pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i, | |
275 | nlimbs); | |
276 | BUG(); | |
277 | } | |
278 | return 0; | |
279 | } | |
280 | EXPORT_SYMBOL_GPL(mpi_set_buffer); |