Commit | Line | Data |
---|---|---|
2fe58dfd SE |
1 | /*************************************************************************** |
2 | * | |
3 | * Part II Project, "A secure, private IP network" | |
4 | * Stephen Early <sde1000@cam.ac.uk> | |
5 | * | |
6 | * | |
7 | * $RCSfile: rsa.c,v $ | |
8 | * | |
9 | * Description: RSA signature making and checking functions | |
10 | * | |
11 | * Copyright: (C) Stephen Early 1995 | |
12 | * | |
13 | * $Revision: 1.1 $ | |
14 | * | |
15 | * $Date: 1996/05/16 18:40:14 $ | |
16 | * | |
17 | * $State: Exp $ | |
18 | * | |
19 | ***************************************************************************/ | |
20 | ||
21 | /* $Log: rsa.c,v $ | |
22 | * Revision 1.1 1996/05/16 18:40:14 sde1000 | |
23 | * Initial revision | |
24 | * | |
25 | */ | |
26 | ||
27 | #include <stdio.h> | |
28 | #include <gmp.h> | |
29 | #include "secnet.h" | |
30 | #include "util.h" | |
31 | ||
32 | #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n" | |
33 | ||
34 | struct rsapriv { | |
35 | closure_t cl; | |
36 | struct rsaprivkey_if ops; | |
37 | struct cloc loc; | |
38 | MP_INT d; | |
39 | MP_INT n; | |
40 | }; | |
41 | struct rsapub { | |
42 | closure_t cl; | |
43 | struct rsapubkey_if ops; | |
44 | struct cloc loc; | |
45 | MP_INT e; | |
46 | MP_INT n; | |
47 | }; | |
48 | /* Sign data. NB data must be smaller than modulus */ | |
49 | ||
50 | static char *hexchars="0123456789abcdef"; | |
51 | ||
52 | static string_t rsa_sign(void *sst, uint8_t *data, uint32_t datalen) | |
53 | { | |
54 | struct rsapriv *st=sst; | |
55 | MP_INT a, b; | |
56 | char buff[2048]; | |
57 | int msize, i; | |
58 | string_t signature; | |
59 | ||
60 | mpz_init(&a); | |
61 | mpz_init(&b); | |
62 | ||
63 | msize=mpz_sizeinbase(&st->n, 16); | |
64 | ||
3454dce4 SE |
65 | if (datalen*2+4>=msize) { |
66 | fatal("rsa_sign: message too big\n"); | |
67 | } | |
68 | ||
2fe58dfd SE |
69 | strcpy(buff,"0001"); |
70 | ||
71 | for (i=0; i<datalen; i++) { | |
72 | buff[4+i*2]=hexchars[(data[i]&0xf0)>>4]; | |
73 | buff[5+i*2]=hexchars[data[i]&0xf]; | |
74 | } | |
75 | buff[4+datalen*2]=0; | |
3454dce4 | 76 | |
2fe58dfd SE |
77 | for (i=datalen*2+4; i<msize; i++) |
78 | buff[i]='f'; | |
79 | ||
80 | buff[msize]=0; | |
81 | ||
82 | mpz_set_str(&a, buff, 16); | |
83 | ||
84 | mpz_powm(&b, &a, &st->d, &st->n); | |
85 | ||
86 | signature=write_mpstring(&b); | |
87 | ||
88 | mpz_clear(&b); | |
89 | mpz_clear(&a); | |
90 | return signature; | |
91 | } | |
92 | ||
93 | static bool_t rsa_sig_check(void *sst, uint8_t *data, uint32_t datalen, | |
94 | string_t signature) | |
95 | { | |
96 | struct rsapub *st=sst; | |
97 | MP_INT a, b, c; | |
98 | char buff[2048]; | |
99 | int msize, i; | |
100 | bool_t ok; | |
101 | ||
102 | mpz_init(&a); | |
103 | mpz_init(&b); | |
104 | mpz_init(&c); | |
105 | ||
106 | msize=mpz_sizeinbase(&st->n, 16); | |
107 | ||
108 | strcpy(buff,"0001"); | |
109 | ||
110 | for (i=0; i<datalen; i++) { | |
111 | buff[4+i*2]=hexchars[(data[i]&0xf0)>>4]; | |
112 | buff[5+i*2]=hexchars[data[i]&0xf]; | |
113 | } | |
114 | buff[4+datalen*2]=0; | |
115 | ||
116 | for (i=datalen*2+4; i<msize; i++) | |
117 | buff[i]='f'; | |
118 | ||
119 | buff[msize]=0; | |
120 | ||
121 | mpz_set_str(&a, buff, 16); | |
122 | ||
123 | mpz_set_str(&b, signature, 16); | |
124 | ||
125 | mpz_powm(&c, &b, &st->e, &st->n); | |
126 | ||
127 | ok=(mpz_cmp(&a, &c)==0); | |
128 | ||
129 | mpz_clear(&c); | |
130 | mpz_clear(&b); | |
131 | mpz_clear(&a); | |
132 | ||
133 | return ok; | |
134 | } | |
135 | ||
136 | static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context, | |
137 | list_t *args) | |
138 | { | |
139 | struct rsapub *st; | |
140 | item_t *i; | |
141 | string_t e,n; | |
142 | ||
143 | st=safe_malloc(sizeof(*st),"rsapub_apply"); | |
144 | st->cl.description="rsapub"; | |
145 | st->cl.type=CL_RSAPUBKEY; | |
146 | st->cl.apply=NULL; | |
147 | st->cl.interface=&st->ops; | |
148 | st->ops.st=st; | |
149 | st->ops.check=rsa_sig_check; | |
150 | st->loc=loc; | |
151 | ||
152 | i=list_elem(args,0); | |
153 | if (i) { | |
154 | if (i->type!=t_string) { | |
155 | cfgfatal(i->loc,"rsa-public","first argument must be a string"); | |
156 | } | |
157 | e=i->data.string; | |
158 | if (mpz_init_set_str(&st->e,e,10)!=0) { | |
159 | cfgfatal(i->loc,"rsa-public","encryption key \"%s\" is not a " | |
160 | "decimal number string\n",e); | |
161 | } | |
162 | } else { | |
163 | cfgfatal(loc,"rsa-public","you must provide an encryption key\n"); | |
164 | } | |
165 | ||
166 | i=list_elem(args,1); | |
167 | if (i) { | |
168 | if (i->type!=t_string) { | |
169 | cfgfatal(i->loc,"rsa-public","second argument must be a string"); | |
170 | } | |
171 | n=i->data.string; | |
172 | if (mpz_init_set_str(&st->n,n,10)!=0) { | |
173 | cfgfatal(i->loc,"rsa-public","modulus \"%s\" is not a decimal " | |
174 | "number string\n",n); | |
175 | } | |
176 | } else { | |
177 | cfgfatal(loc,"rsa-public","you must provide a modulus\n"); | |
178 | } | |
179 | return new_closure(&st->cl); | |
180 | } | |
181 | ||
182 | static uint32_t keyfile_get_int(FILE *f) | |
183 | { | |
184 | uint32_t r; | |
185 | r=fgetc(f)<<24; | |
186 | r|=fgetc(f)<<16; | |
187 | r|=fgetc(f)<<8; | |
188 | r|=fgetc(f); | |
189 | return r; | |
190 | } | |
191 | ||
192 | static uint16_t keyfile_get_short(FILE *f) | |
193 | { | |
194 | uint16_t r; | |
195 | r=fgetc(f)<<8; | |
196 | r|=fgetc(f); | |
197 | return r; | |
198 | } | |
199 | ||
200 | static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context, | |
201 | list_t *args) | |
202 | { | |
203 | struct rsapriv *st; | |
204 | FILE *f; | |
205 | string_t filename; | |
206 | item_t *i; | |
207 | long length; | |
208 | uint8_t *b, *c; | |
209 | int cipher_type; | |
210 | MP_INT e,sig,plain,check; | |
211 | ||
212 | st=safe_malloc(sizeof(*st),"rsapriv_apply"); | |
213 | st->cl.description="rsapriv"; | |
214 | st->cl.type=CL_RSAPRIVKEY; | |
215 | st->cl.apply=NULL; | |
216 | st->cl.interface=&st->ops; | |
217 | st->ops.st=st; | |
218 | st->ops.sign=rsa_sign; | |
219 | st->loc=loc; | |
220 | ||
221 | /* Argument is filename pointing to SSH1 private key file */ | |
222 | i=list_elem(args,0); | |
223 | if (i) { | |
224 | if (i->type!=t_string) { | |
225 | cfgfatal(i->loc,"rsa-public","first argument must be a string"); | |
226 | } | |
227 | filename=i->data.string; | |
228 | } else { | |
229 | filename=""; /* Make compiler happy */ | |
230 | cfgfatal(loc,"rsa-private","you must provide a filename\n"); | |
231 | } | |
232 | ||
233 | f=fopen(filename,"rb"); | |
234 | if (!f) { | |
baa06aeb SE |
235 | if (just_check_config) { |
236 | Message(M_WARNING,"rsa-private (%s:%d): cannot open keyfile " | |
237 | "\"%s\"; assuming it's valid while we check the " | |
238 | "rest of the configuration\n",loc.file,loc.line,filename); | |
239 | goto assume_valid; | |
240 | } else { | |
241 | fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"", | |
242 | loc.file,loc.line,filename); | |
243 | } | |
2fe58dfd SE |
244 | } |
245 | ||
246 | /* Check that the ID string is correct */ | |
247 | length=strlen(AUTHFILE_ID_STRING)+1; | |
248 | b=safe_malloc(length,"rsapriv_apply"); | |
249 | if (fread(b,length,1,f)!=1 || memcmp(b,AUTHFILE_ID_STRING,length)!=0) { | |
250 | cfgfatal(loc,"rsa-private","file \"%s\" is not a " | |
251 | "SSH1 private keyfile\n",filename); | |
252 | } | |
253 | free(b); | |
254 | ||
255 | cipher_type=fgetc(f); | |
256 | keyfile_get_int(f); /* "Reserved data" */ | |
257 | if (cipher_type != 0) { | |
258 | cfgfatal(loc,"rsa-private","we don't support encrypted keyfiles\n"); | |
259 | } | |
260 | ||
261 | /* Read the public key */ | |
262 | keyfile_get_int(f); /* Not sure what this is */ | |
263 | length=(keyfile_get_short(f)+7)/8; | |
264 | if (length>1024) { | |
265 | cfgfatal(loc,"rsa-private","implausible length %ld for modulus\n", | |
266 | length); | |
267 | } | |
268 | b=safe_malloc(length,"rsapriv_apply"); | |
269 | if (fread(b,length,1,f) != 1) { | |
270 | cfgfatal(loc,"rsa-private","error reading modulus\n"); | |
271 | } | |
272 | mpz_init(&st->n); | |
273 | read_mpbin(&st->n,b,length); | |
274 | free(b); | |
275 | length=(keyfile_get_short(f)+7)/8; | |
276 | if (length>1024) { | |
277 | cfgfatal(loc,"rsa-private","implausible length %ld for e\n",length); | |
278 | } | |
279 | b=safe_malloc(length,"rsapriv_apply"); | |
280 | if (fread(b,length,1,f)!=1) { | |
281 | cfgfatal(loc,"rsa-private","error reading e\n"); | |
282 | } | |
283 | mpz_init(&e); | |
284 | read_mpbin(&e,b,length); | |
285 | free(b); | |
286 | ||
287 | length=keyfile_get_int(f); | |
288 | if (length>1024) { | |
289 | cfgfatal(loc,"rsa-private","implausibly long (%ld) key comment\n", | |
290 | length); | |
291 | } | |
292 | c=safe_malloc(length+1,"rsapriv_apply"); | |
293 | if (fread(c,length,1,f)!=1) { | |
294 | cfgfatal(loc,"rsa-private","error reading key comment\n"); | |
295 | } | |
296 | c[length]=0; | |
297 | ||
298 | /* Check that the next two pairs of characters are identical - the | |
299 | keyfile is not encrypted, so they should be */ | |
300 | if (keyfile_get_short(f) != keyfile_get_short(f)) { | |
301 | cfgfatal(loc,"rsa-private","corrupt keyfile\n"); | |
302 | } | |
303 | ||
304 | /* Read d */ | |
305 | length=(keyfile_get_short(f)+7)/8; | |
306 | if (length>1024) { | |
307 | cfgfatal(loc,"rsa-private","implausibly long (%ld) decryption key\n", | |
308 | length); | |
309 | } | |
310 | b=safe_malloc(length,"rsapriv_apply"); | |
311 | if (fread(b,length,1,f)!=1) { | |
312 | cfgfatal(loc,"rsa-private","error reading decryption key\n"); | |
313 | } | |
314 | mpz_init(&st->d); | |
315 | read_mpbin(&st->d,b,length); | |
316 | free(b); | |
317 | ||
318 | if (fclose(f)!=0) { | |
319 | fatal_perror("rsa-private (%s:%d): fclose",loc.file,loc.line); | |
320 | } | |
321 | ||
322 | /* Now do trial signature/check to make sure it's a real keypair: | |
323 | sign the comment string! */ | |
70dc107b SE |
324 | i=list_elem(args,1); |
325 | if (i && i->type==t_bool && i->data.bool==False) { | |
326 | Message(M_INFO,"rsa-private (%s:%d): skipping RSA key validity " | |
327 | "check\n",loc.file,loc.line); | |
328 | } else { | |
329 | mpz_init(&sig); | |
330 | mpz_init(&plain); | |
331 | mpz_init(&check); | |
332 | read_mpbin(&plain,c,strlen(c)); | |
333 | mpz_powm(&sig, &plain, &st->d, &st->n); | |
334 | mpz_powm(&check, &sig, &e, &st->n); | |
335 | if (mpz_cmp(&plain,&check)!=0) { | |
336 | cfgfatal(loc,"rsa-private","file \"%s\" does not contain a " | |
337 | "valid RSA key!\n",filename); | |
338 | } | |
339 | mpz_clear(&sig); | |
340 | mpz_clear(&plain); | |
341 | mpz_clear(&check); | |
2fe58dfd | 342 | } |
2fe58dfd SE |
343 | |
344 | free(c); | |
345 | mpz_clear(&e); | |
346 | ||
baa06aeb | 347 | assume_valid: |
2fe58dfd SE |
348 | return new_closure(&st->cl); |
349 | } | |
350 | ||
351 | init_module rsa_module; | |
352 | void rsa_module(dict_t *dict) | |
353 | { | |
354 | add_closure(dict,"rsa-private",rsapriv_apply); | |
355 | add_closure(dict,"rsa-public",rsapub_apply); | |
356 | } |