Commit | Line | Data |
---|---|---|
fe5e9cc4 SE |
1 | /* CRT work by Simon Tatham */ |
2 | ||
2fe58dfd SE |
3 | #include <stdio.h> |
4 | #include <gmp.h> | |
5 | #include "secnet.h" | |
6 | #include "util.h" | |
7 | ||
8 | #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n" | |
9 | ||
fe5e9cc4 SE |
10 | #define mpp(s,n) do { char *p = mpz_get_str(NULL,16,n); printf("%s 0x%sL\n", s, p); free(p); } while (0) |
11 | ||
2fe58dfd SE |
12 | struct rsapriv { |
13 | closure_t cl; | |
14 | struct rsaprivkey_if ops; | |
15 | struct cloc loc; | |
2fe58dfd | 16 | MP_INT n; |
fe5e9cc4 SE |
17 | MP_INT p, dp; |
18 | MP_INT q, dq; | |
19 | MP_INT w; | |
2fe58dfd SE |
20 | }; |
21 | struct rsapub { | |
22 | closure_t cl; | |
23 | struct rsapubkey_if ops; | |
24 | struct cloc loc; | |
25 | MP_INT e; | |
26 | MP_INT n; | |
27 | }; | |
28 | /* Sign data. NB data must be smaller than modulus */ | |
29 | ||
fe5e9cc4 | 30 | static const char *hexchars="0123456789abcdef"; |
2fe58dfd SE |
31 | |
32 | static string_t rsa_sign(void *sst, uint8_t *data, uint32_t datalen) | |
33 | { | |
34 | struct rsapriv *st=sst; | |
fe5e9cc4 | 35 | MP_INT a, b, u, v, tmp, tmp2; |
2fe58dfd SE |
36 | char buff[2048]; |
37 | int msize, i; | |
38 | string_t signature; | |
39 | ||
40 | mpz_init(&a); | |
41 | mpz_init(&b); | |
42 | ||
43 | msize=mpz_sizeinbase(&st->n, 16); | |
44 | ||
3454dce4 | 45 | if (datalen*2+4>=msize) { |
4f5e39ec | 46 | fatal("rsa_sign: message too big"); |
3454dce4 SE |
47 | } |
48 | ||
2fe58dfd SE |
49 | strcpy(buff,"0001"); |
50 | ||
51 | for (i=0; i<datalen; i++) { | |
52 | buff[4+i*2]=hexchars[(data[i]&0xf0)>>4]; | |
53 | buff[5+i*2]=hexchars[data[i]&0xf]; | |
54 | } | |
55 | buff[4+datalen*2]=0; | |
3454dce4 | 56 | |
2fe58dfd SE |
57 | for (i=datalen*2+4; i<msize; i++) |
58 | buff[i]='f'; | |
59 | ||
60 | buff[msize]=0; | |
61 | ||
62 | mpz_set_str(&a, buff, 16); | |
63 | ||
fe5e9cc4 SE |
64 | /* |
65 | * Produce an RSA signature (a^d mod n) using the Chinese | |
66 | * Remainder Theorem. We compute: | |
67 | * | |
68 | * u = a^dp mod p (== a^d mod p, since dp == d mod (p-1)) | |
69 | * v = a^dq mod q (== a^d mod q, similarly) | |
70 | * | |
71 | * We also know w == iqmp * q, which has the property that w == | |
72 | * 0 mod q and w == 1 mod p. So (1-w) has the reverse property | |
73 | * (congruent to 0 mod p and to 1 mod q). Hence we now compute | |
74 | * | |
75 | * b = w * u + (1-w) * v | |
76 | * = w * (u-v) + v | |
77 | * | |
78 | * so that b is congruent to a^d both mod p and mod q. Hence b, | |
79 | * reduced mod n, is the required signature. | |
80 | */ | |
81 | mpz_init(&tmp); | |
82 | mpz_init(&tmp2); | |
83 | mpz_init(&u); | |
84 | mpz_init(&v); | |
85 | ||
86 | mpz_powm(&u, &a, &st->dp, &st->p); | |
87 | mpz_powm(&v, &a, &st->dq, &st->q); | |
88 | mpz_sub(&tmp, &u, &v); | |
89 | mpz_mul(&tmp2, &tmp, &st->w); | |
90 | mpz_add(&tmp, &tmp2, &v); | |
91 | mpz_mod(&b, &tmp, &st->n); | |
92 | ||
93 | mpz_clear(&tmp); | |
94 | mpz_clear(&tmp2); | |
95 | mpz_clear(&u); | |
96 | mpz_clear(&v); | |
2fe58dfd SE |
97 | |
98 | signature=write_mpstring(&b); | |
99 | ||
100 | mpz_clear(&b); | |
101 | mpz_clear(&a); | |
102 | return signature; | |
103 | } | |
104 | ||
fe5e9cc4 | 105 | static rsa_checksig_fn rsa_sig_check; |
2fe58dfd | 106 | static bool_t rsa_sig_check(void *sst, uint8_t *data, uint32_t datalen, |
fe5e9cc4 | 107 | cstring_t signature) |
2fe58dfd SE |
108 | { |
109 | struct rsapub *st=sst; | |
110 | MP_INT a, b, c; | |
111 | char buff[2048]; | |
112 | int msize, i; | |
113 | bool_t ok; | |
114 | ||
115 | mpz_init(&a); | |
116 | mpz_init(&b); | |
117 | mpz_init(&c); | |
118 | ||
119 | msize=mpz_sizeinbase(&st->n, 16); | |
120 | ||
121 | strcpy(buff,"0001"); | |
122 | ||
123 | for (i=0; i<datalen; i++) { | |
124 | buff[4+i*2]=hexchars[(data[i]&0xf0)>>4]; | |
125 | buff[5+i*2]=hexchars[data[i]&0xf]; | |
126 | } | |
127 | buff[4+datalen*2]=0; | |
128 | ||
129 | for (i=datalen*2+4; i<msize; i++) | |
130 | buff[i]='f'; | |
131 | ||
132 | buff[msize]=0; | |
133 | ||
134 | mpz_set_str(&a, buff, 16); | |
135 | ||
136 | mpz_set_str(&b, signature, 16); | |
137 | ||
138 | mpz_powm(&c, &b, &st->e, &st->n); | |
139 | ||
140 | ok=(mpz_cmp(&a, &c)==0); | |
141 | ||
142 | mpz_clear(&c); | |
143 | mpz_clear(&b); | |
144 | mpz_clear(&a); | |
145 | ||
146 | return ok; | |
147 | } | |
148 | ||
149 | static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context, | |
150 | list_t *args) | |
151 | { | |
152 | struct rsapub *st; | |
153 | item_t *i; | |
154 | string_t e,n; | |
155 | ||
156 | st=safe_malloc(sizeof(*st),"rsapub_apply"); | |
157 | st->cl.description="rsapub"; | |
158 | st->cl.type=CL_RSAPUBKEY; | |
159 | st->cl.apply=NULL; | |
160 | st->cl.interface=&st->ops; | |
161 | st->ops.st=st; | |
162 | st->ops.check=rsa_sig_check; | |
163 | st->loc=loc; | |
164 | ||
165 | i=list_elem(args,0); | |
166 | if (i) { | |
167 | if (i->type!=t_string) { | |
168 | cfgfatal(i->loc,"rsa-public","first argument must be a string"); | |
169 | } | |
170 | e=i->data.string; | |
171 | if (mpz_init_set_str(&st->e,e,10)!=0) { | |
172 | cfgfatal(i->loc,"rsa-public","encryption key \"%s\" is not a " | |
173 | "decimal number string\n",e); | |
174 | } | |
175 | } else { | |
176 | cfgfatal(loc,"rsa-public","you must provide an encryption key\n"); | |
177 | } | |
178 | ||
179 | i=list_elem(args,1); | |
180 | if (i) { | |
181 | if (i->type!=t_string) { | |
182 | cfgfatal(i->loc,"rsa-public","second argument must be a string"); | |
183 | } | |
184 | n=i->data.string; | |
185 | if (mpz_init_set_str(&st->n,n,10)!=0) { | |
186 | cfgfatal(i->loc,"rsa-public","modulus \"%s\" is not a decimal " | |
187 | "number string\n",n); | |
188 | } | |
189 | } else { | |
190 | cfgfatal(loc,"rsa-public","you must provide a modulus\n"); | |
191 | } | |
192 | return new_closure(&st->cl); | |
193 | } | |
194 | ||
4f5e39ec | 195 | static uint32_t keyfile_get_int(struct cloc loc, FILE *f) |
2fe58dfd SE |
196 | { |
197 | uint32_t r; | |
198 | r=fgetc(f)<<24; | |
199 | r|=fgetc(f)<<16; | |
200 | r|=fgetc(f)<<8; | |
201 | r|=fgetc(f); | |
4f5e39ec | 202 | cfgfile_postreadcheck(loc,f); |
2fe58dfd SE |
203 | return r; |
204 | } | |
205 | ||
4f5e39ec | 206 | static uint16_t keyfile_get_short(struct cloc loc, FILE *f) |
2fe58dfd SE |
207 | { |
208 | uint16_t r; | |
209 | r=fgetc(f)<<8; | |
210 | r|=fgetc(f); | |
4f5e39ec | 211 | cfgfile_postreadcheck(loc,f); |
2fe58dfd SE |
212 | return r; |
213 | } | |
214 | ||
215 | static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context, | |
216 | list_t *args) | |
217 | { | |
218 | struct rsapriv *st; | |
219 | FILE *f; | |
fe5e9cc4 | 220 | cstring_t filename; |
2fe58dfd SE |
221 | item_t *i; |
222 | long length; | |
223 | uint8_t *b, *c; | |
224 | int cipher_type; | |
fe5e9cc4 | 225 | MP_INT e,d,iqmp,tmp,tmp2,tmp3; |
2fe58dfd SE |
226 | |
227 | st=safe_malloc(sizeof(*st),"rsapriv_apply"); | |
228 | st->cl.description="rsapriv"; | |
229 | st->cl.type=CL_RSAPRIVKEY; | |
230 | st->cl.apply=NULL; | |
231 | st->cl.interface=&st->ops; | |
232 | st->ops.st=st; | |
233 | st->ops.sign=rsa_sign; | |
234 | st->loc=loc; | |
235 | ||
236 | /* Argument is filename pointing to SSH1 private key file */ | |
237 | i=list_elem(args,0); | |
238 | if (i) { | |
239 | if (i->type!=t_string) { | |
240 | cfgfatal(i->loc,"rsa-public","first argument must be a string"); | |
241 | } | |
242 | filename=i->data.string; | |
243 | } else { | |
fe5e9cc4 | 244 | filename=NULL; /* Make compiler happy */ |
2fe58dfd SE |
245 | cfgfatal(loc,"rsa-private","you must provide a filename\n"); |
246 | } | |
247 | ||
248 | f=fopen(filename,"rb"); | |
249 | if (!f) { | |
baa06aeb SE |
250 | if (just_check_config) { |
251 | Message(M_WARNING,"rsa-private (%s:%d): cannot open keyfile " | |
252 | "\"%s\"; assuming it's valid while we check the " | |
253 | "rest of the configuration\n",loc.file,loc.line,filename); | |
254 | goto assume_valid; | |
255 | } else { | |
256 | fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"", | |
257 | loc.file,loc.line,filename); | |
258 | } | |
2fe58dfd SE |
259 | } |
260 | ||
261 | /* Check that the ID string is correct */ | |
262 | length=strlen(AUTHFILE_ID_STRING)+1; | |
263 | b=safe_malloc(length,"rsapriv_apply"); | |
264 | if (fread(b,length,1,f)!=1 || memcmp(b,AUTHFILE_ID_STRING,length)!=0) { | |
4f5e39ec SE |
265 | cfgfatal_maybefile(f,loc,"rsa-private","failed to read magic ID" |
266 | " string from SSH1 private keyfile \"%s\"\n", | |
267 | filename); | |
2fe58dfd SE |
268 | } |
269 | free(b); | |
270 | ||
271 | cipher_type=fgetc(f); | |
4f5e39ec | 272 | keyfile_get_int(loc,f); /* "Reserved data" */ |
2fe58dfd SE |
273 | if (cipher_type != 0) { |
274 | cfgfatal(loc,"rsa-private","we don't support encrypted keyfiles\n"); | |
275 | } | |
276 | ||
277 | /* Read the public key */ | |
4f5e39ec SE |
278 | keyfile_get_int(loc,f); /* Not sure what this is */ |
279 | length=(keyfile_get_short(loc,f)+7)/8; | |
2fe58dfd SE |
280 | if (length>1024) { |
281 | cfgfatal(loc,"rsa-private","implausible length %ld for modulus\n", | |
282 | length); | |
283 | } | |
284 | b=safe_malloc(length,"rsapriv_apply"); | |
285 | if (fread(b,length,1,f) != 1) { | |
4f5e39ec | 286 | cfgfatal_maybefile(f,loc,"rsa-private","error reading modulus"); |
2fe58dfd SE |
287 | } |
288 | mpz_init(&st->n); | |
289 | read_mpbin(&st->n,b,length); | |
290 | free(b); | |
4f5e39ec | 291 | length=(keyfile_get_short(loc,f)+7)/8; |
2fe58dfd SE |
292 | if (length>1024) { |
293 | cfgfatal(loc,"rsa-private","implausible length %ld for e\n",length); | |
294 | } | |
295 | b=safe_malloc(length,"rsapriv_apply"); | |
296 | if (fread(b,length,1,f)!=1) { | |
4f5e39ec | 297 | cfgfatal_maybefile(f,loc,"rsa-private","error reading e\n"); |
2fe58dfd SE |
298 | } |
299 | mpz_init(&e); | |
300 | read_mpbin(&e,b,length); | |
301 | free(b); | |
302 | ||
4f5e39ec | 303 | length=keyfile_get_int(loc,f); |
2fe58dfd SE |
304 | if (length>1024) { |
305 | cfgfatal(loc,"rsa-private","implausibly long (%ld) key comment\n", | |
306 | length); | |
307 | } | |
308 | c=safe_malloc(length+1,"rsapriv_apply"); | |
309 | if (fread(c,length,1,f)!=1) { | |
4f5e39ec | 310 | cfgfatal_maybefile(f,loc,"rsa-private","error reading key comment\n"); |
2fe58dfd SE |
311 | } |
312 | c[length]=0; | |
313 | ||
314 | /* Check that the next two pairs of characters are identical - the | |
315 | keyfile is not encrypted, so they should be */ | |
4f5e39ec SE |
316 | |
317 | if (keyfile_get_short(loc,f) != keyfile_get_short(loc,f)) { | |
2fe58dfd SE |
318 | cfgfatal(loc,"rsa-private","corrupt keyfile\n"); |
319 | } | |
320 | ||
321 | /* Read d */ | |
4f5e39ec | 322 | length=(keyfile_get_short(loc,f)+7)/8; |
2fe58dfd SE |
323 | if (length>1024) { |
324 | cfgfatal(loc,"rsa-private","implausibly long (%ld) decryption key\n", | |
325 | length); | |
326 | } | |
327 | b=safe_malloc(length,"rsapriv_apply"); | |
328 | if (fread(b,length,1,f)!=1) { | |
4f5e39ec SE |
329 | cfgfatal_maybefile(f,loc,"rsa-private", |
330 | "error reading decryption key\n"); | |
2fe58dfd | 331 | } |
fe5e9cc4 SE |
332 | mpz_init(&d); |
333 | read_mpbin(&d,b,length); | |
334 | free(b); | |
335 | /* Read iqmp (inverse of q mod p) */ | |
336 | length=(keyfile_get_short(loc,f)+7)/8; | |
337 | if (length>1024) { | |
338 | cfgfatal(loc,"rsa-private","implausibly long (%ld)" | |
339 | " iqmp auxiliary value\n", length); | |
340 | } | |
341 | b=safe_malloc(length,"rsapriv_apply"); | |
342 | if (fread(b,length,1,f)!=1) { | |
343 | cfgfatal_maybefile(f,loc,"rsa-private", | |
344 | "error reading decryption key\n"); | |
345 | } | |
346 | mpz_init(&iqmp); | |
347 | read_mpbin(&iqmp,b,length); | |
348 | free(b); | |
349 | /* Read q (the smaller of the two primes) */ | |
350 | length=(keyfile_get_short(loc,f)+7)/8; | |
351 | if (length>1024) { | |
352 | cfgfatal(loc,"rsa-private","implausibly long (%ld) q value\n", | |
353 | length); | |
354 | } | |
355 | b=safe_malloc(length,"rsapriv_apply"); | |
356 | if (fread(b,length,1,f)!=1) { | |
357 | cfgfatal_maybefile(f,loc,"rsa-private", | |
358 | "error reading q value\n"); | |
359 | } | |
360 | mpz_init(&st->q); | |
361 | read_mpbin(&st->q,b,length); | |
362 | free(b); | |
363 | /* Read p (the larger of the two primes) */ | |
364 | length=(keyfile_get_short(loc,f)+7)/8; | |
365 | if (length>1024) { | |
366 | cfgfatal(loc,"rsa-private","implausibly long (%ld) p value\n", | |
367 | length); | |
368 | } | |
369 | b=safe_malloc(length,"rsapriv_apply"); | |
370 | if (fread(b,length,1,f)!=1) { | |
371 | cfgfatal_maybefile(f,loc,"rsa-private", | |
372 | "error reading p value\n"); | |
373 | } | |
374 | mpz_init(&st->p); | |
375 | read_mpbin(&st->p,b,length); | |
2fe58dfd SE |
376 | free(b); |
377 | ||
378 | if (fclose(f)!=0) { | |
379 | fatal_perror("rsa-private (%s:%d): fclose",loc.file,loc.line); | |
380 | } | |
381 | ||
fe5e9cc4 SE |
382 | /* |
383 | * Now verify the validity of the key, and set up the auxiliary | |
384 | * values for fast CRT signing. | |
385 | */ | |
70dc107b SE |
386 | i=list_elem(args,1); |
387 | if (i && i->type==t_bool && i->data.bool==False) { | |
388 | Message(M_INFO,"rsa-private (%s:%d): skipping RSA key validity " | |
389 | "check\n",loc.file,loc.line); | |
390 | } else { | |
fe5e9cc4 SE |
391 | int valid = 0; |
392 | mpz_init(&tmp); | |
393 | mpz_init(&tmp2); | |
394 | mpz_init(&tmp3); | |
395 | ||
396 | /* Verify that p*q is equal to n. */ | |
397 | mpz_mul(&tmp, &st->p, &st->q); | |
398 | if (mpz_cmp(&tmp, &st->n) != 0) | |
399 | goto done_checks; | |
400 | ||
401 | /* | |
402 | * Verify that d*e is congruent to 1 mod (p-1), and mod | |
403 | * (q-1). This is equivalent to it being congruent to 1 mod | |
404 | * lcm(p-1,q-1), i.e. congruent to 1 mod phi(n). Note that | |
405 | * phi(n) is _not_ simply (p-1)*(q-1). | |
406 | */ | |
407 | mpz_mul(&tmp, &d, &e); | |
408 | mpz_sub_ui(&tmp2, &st->p, 1); | |
409 | mpz_mod(&tmp3, &tmp, &tmp2); | |
410 | if (mpz_cmp_si(&tmp3, 1) != 0) | |
411 | goto done_checks; | |
412 | mpz_sub_ui(&tmp2, &st->q, 1); | |
413 | mpz_mod(&tmp3, &tmp, &tmp2); | |
414 | if (mpz_cmp_si(&tmp3, 1) != 0) | |
415 | goto done_checks; | |
416 | ||
417 | /* Verify that q*iqmp is congruent to 1 mod p. */ | |
418 | mpz_mul(&tmp, &st->q, &iqmp); | |
419 | mpz_mod(&tmp2, &tmp, &st->p); | |
420 | if (mpz_cmp_si(&tmp2, 1) != 0) | |
421 | goto done_checks; | |
422 | ||
423 | /* Now we know the key is valid. */ | |
424 | valid = 1; | |
425 | ||
426 | /* | |
427 | * Now we compute auxiliary values dp, dq and w to allow us | |
428 | * to use the CRT optimisation when signing. | |
429 | * | |
430 | * dp == d mod (p-1) so that a^dp == a^d mod p, for all a | |
431 | * dq == d mod (q-1) similarly mod q | |
432 | * w == iqmp * q so that w == 0 mod q, and w == 1 mod p | |
433 | */ | |
434 | mpz_sub_ui(&tmp, &st->p, 1); | |
435 | mpz_mod(&st->dp, &d, &tmp); | |
436 | mpz_sub_ui(&tmp, &st->q, 1); | |
437 | mpz_mod(&st->dq, &d, &tmp); | |
438 | mpz_mul(&st->w, &iqmp, &st->q); | |
439 | ||
440 | done_checks: | |
441 | if (!valid) { | |
70dc107b SE |
442 | cfgfatal(loc,"rsa-private","file \"%s\" does not contain a " |
443 | "valid RSA key!\n",filename); | |
444 | } | |
fe5e9cc4 SE |
445 | mpz_clear(&tmp); |
446 | mpz_clear(&tmp2); | |
447 | mpz_clear(&tmp3); | |
2fe58dfd | 448 | } |
2fe58dfd SE |
449 | |
450 | free(c); | |
451 | mpz_clear(&e); | |
fe5e9cc4 SE |
452 | mpz_clear(&d); |
453 | mpz_clear(&iqmp); | |
2fe58dfd | 454 | |
baa06aeb | 455 | assume_valid: |
2fe58dfd SE |
456 | return new_closure(&st->cl); |
457 | } | |
458 | ||
459 | init_module rsa_module; | |
460 | void rsa_module(dict_t *dict) | |
461 | { | |
462 | add_closure(dict,"rsa-private",rsapriv_apply); | |
463 | add_closure(dict,"rsa-public",rsapub_apply); | |
464 | } |