374330e2 |
1 | /* |
2 | * RSA implementation just sufficient for ssh client-side |
3 | * initialisation step |
4644b0ce |
4 | * |
5 | * Rewritten for more speed by Joris van Rantwijk, Jun 1999. |
374330e2 |
6 | */ |
7 | |
374330e2 |
8 | #include <stdio.h> |
9 | #include <stdlib.h> |
10 | #include <string.h> |
65a22376 |
11 | #include <assert.h> |
374330e2 |
12 | |
e5574168 |
13 | #include "ssh.h" |
374330e2 |
14 | |
1c2a93c4 |
15 | |
374330e2 |
16 | int makekey(unsigned char *data, struct RSAKey *result, |
7cca0d81 |
17 | unsigned char **keystr, int order) { |
374330e2 |
18 | unsigned char *p = data; |
7cca0d81 |
19 | int i; |
374330e2 |
20 | |
a52f067e |
21 | if (result) { |
22 | result->bits = 0; |
23 | for (i=0; i<4; i++) |
24 | result->bits = (result->bits << 8) + *p++; |
25 | } else |
26 | p += 4; |
374330e2 |
27 | |
7cca0d81 |
28 | /* |
29 | * order=0 means exponent then modulus (the keys sent by the |
30 | * server). order=1 means modulus then exponent (the keys |
31 | * stored in a keyfile). |
32 | */ |
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33 | |
7cca0d81 |
34 | if (order == 0) |
a52f067e |
35 | p += ssh1_read_bignum(p, result ? &result->exponent : NULL); |
36 | if (result) |
37 | result->bytes = (((p[0] << 8) + p[1]) + 7) / 8; |
7cca0d81 |
38 | if (keystr) *keystr = p+2; |
a52f067e |
39 | p += ssh1_read_bignum(p, result ? &result->modulus : NULL); |
7cca0d81 |
40 | if (order == 1) |
a52f067e |
41 | p += ssh1_read_bignum(p, result ? &result->exponent : NULL); |
374330e2 |
42 | |
43 | return p - data; |
44 | } |
45 | |
7cca0d81 |
46 | int makeprivate(unsigned char *data, struct RSAKey *result) { |
47 | return ssh1_read_bignum(data, &result->private_exponent); |
48 | } |
49 | |
374330e2 |
50 | void rsaencrypt(unsigned char *data, int length, struct RSAKey *key) { |
51 | Bignum b1, b2; |
3709bfe9 |
52 | int i; |
374330e2 |
53 | unsigned char *p; |
54 | |
374330e2 |
55 | memmove(data+key->bytes-length, data, length); |
56 | data[0] = 0; |
57 | data[1] = 2; |
58 | |
59 | for (i = 2; i < key->bytes-length-1; i++) { |
60 | do { |
61 | data[i] = random_byte(); |
62 | } while (data[i] == 0); |
63 | } |
64 | data[key->bytes-length-1] = 0; |
65 | |
3709bfe9 |
66 | b1 = bignum_from_bytes(data, key->bytes); |
374330e2 |
67 | |
59600f67 |
68 | b2 = modpow(b1, key->exponent, key->modulus); |
374330e2 |
69 | |
374330e2 |
70 | p = data; |
d9373729 |
71 | for (i=key->bytes; i-- ;) { |
3709bfe9 |
72 | *p++ = bignum_byte(b2, i); |
374330e2 |
73 | } |
74 | |
75 | freebn(b1); |
76 | freebn(b2); |
77 | } |
78 | |
7cca0d81 |
79 | Bignum rsadecrypt(Bignum input, struct RSAKey *key) { |
80 | Bignum ret; |
59600f67 |
81 | ret = modpow(input, key->private_exponent, key->modulus); |
7cca0d81 |
82 | return ret; |
83 | } |
84 | |
374330e2 |
85 | int rsastr_len(struct RSAKey *key) { |
86 | Bignum md, ex; |
3709bfe9 |
87 | int mdlen, exlen; |
374330e2 |
88 | |
89 | md = key->modulus; |
90 | ex = key->exponent; |
ddecd643 |
91 | mdlen = (bignum_bitcount(md)+15) / 16; |
92 | exlen = (bignum_bitcount(ex)+15) / 16; |
3709bfe9 |
93 | return 4 * (mdlen+exlen) + 20; |
374330e2 |
94 | } |
95 | |
96 | void rsastr_fmt(char *str, struct RSAKey *key) { |
97 | Bignum md, ex; |
d5859615 |
98 | int len = 0, i, nibbles; |
99 | static const char hex[] = "0123456789abcdef"; |
374330e2 |
100 | |
101 | md = key->modulus; |
102 | ex = key->exponent; |
103 | |
d5859615 |
104 | len += sprintf(str+len, "0x"); |
105 | |
ddecd643 |
106 | nibbles = (3 + bignum_bitcount(ex))/4; if (nibbles<1) nibbles=1; |
d5859615 |
107 | for (i=nibbles; i-- ;) |
108 | str[len++] = hex[(bignum_byte(ex, i/2) >> (4*(i%2))) & 0xF]; |
109 | |
110 | len += sprintf(str+len, ",0x"); |
111 | |
ddecd643 |
112 | nibbles = (3 + bignum_bitcount(md))/4; if (nibbles<1) nibbles=1; |
d5859615 |
113 | for (i=nibbles; i-- ;) |
114 | str[len++] = hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]; |
115 | |
374330e2 |
116 | str[len] = '\0'; |
117 | } |
118 | |
1c2a93c4 |
119 | /* |
120 | * Generate a fingerprint string for the key. Compatible with the |
121 | * OpenSSH fingerprint code. |
122 | */ |
123 | void rsa_fingerprint(char *str, int len, struct RSAKey *key) { |
124 | struct MD5Context md5c; |
125 | unsigned char digest[16]; |
126 | char buffer[16*3+40]; |
127 | int numlen, slen, i; |
128 | |
129 | MD5Init(&md5c); |
130 | numlen = ssh1_bignum_length(key->modulus) - 2; |
131 | for (i = numlen; i-- ;) { |
132 | unsigned char c = bignum_byte(key->modulus, i); |
133 | MD5Update(&md5c, &c, 1); |
134 | } |
135 | numlen = ssh1_bignum_length(key->exponent) - 2; |
136 | for (i = numlen; i-- ;) { |
137 | unsigned char c = bignum_byte(key->exponent, i); |
138 | MD5Update(&md5c, &c, 1); |
139 | } |
140 | MD5Final(digest, &md5c); |
141 | |
ddecd643 |
142 | sprintf(buffer, "%d ", bignum_bitcount(key->modulus)); |
1c2a93c4 |
143 | for (i = 0; i < 16; i++) |
144 | sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]); |
145 | strncpy(str, buffer, len); str[len-1] = '\0'; |
146 | slen = strlen(str); |
147 | if (key->comment && slen < len-1) { |
148 | str[slen] = ' '; |
149 | strncpy(str+slen+1, key->comment, len-slen-1); |
150 | str[len-1] = '\0'; |
151 | } |
152 | } |
153 | |
98f022f5 |
154 | /* |
155 | * Verify that the public data in an RSA key matches the private |
60fe6ff7 |
156 | * data. We also check the private data itself: we ensure that p > |
157 | * q and that iqmp really is the inverse of q mod p. |
98f022f5 |
158 | */ |
159 | int rsa_verify(struct RSAKey *key) { |
60fe6ff7 |
160 | Bignum n, ed, pm1, qm1; |
98f022f5 |
161 | int cmp; |
162 | |
163 | /* n must equal pq. */ |
164 | n = bigmul(key->p, key->q); |
165 | cmp = bignum_cmp(n, key->modulus); |
166 | freebn(n); |
167 | if (cmp != 0) |
168 | return 0; |
169 | |
60fe6ff7 |
170 | /* e * d must be congruent to 1, modulo (p-1) and modulo (q-1). */ |
98f022f5 |
171 | pm1 = copybn(key->p); |
172 | decbn(pm1); |
60fe6ff7 |
173 | ed = modmul(key->exponent, key->private_exponent, pm1); |
174 | cmp = bignum_cmp(ed, One); |
175 | sfree(ed); |
176 | if (cmp != 0) |
177 | return 0; |
178 | |
98f022f5 |
179 | qm1 = copybn(key->q); |
180 | decbn(qm1); |
60fe6ff7 |
181 | ed = modmul(key->exponent, key->private_exponent, qm1); |
98f022f5 |
182 | cmp = bignum_cmp(ed, One); |
183 | sfree(ed); |
184 | if (cmp != 0) |
185 | return 0; |
014970c8 |
186 | |
60fe6ff7 |
187 | /* |
188 | * Ensure p > q. |
189 | */ |
190 | if (bignum_cmp(key->p, key->q) <= 0) |
191 | return 0; |
192 | |
193 | /* |
194 | * Ensure iqmp * q is congruent to 1, modulo p. |
195 | */ |
196 | n = modmul(key->iqmp, key->q, key->p); |
197 | cmp = bignum_cmp(n, One); |
198 | sfree(n); |
199 | if (cmp != 0) |
200 | return 0; |
201 | |
014970c8 |
202 | return 1; |
98f022f5 |
203 | } |
204 | |
5c58ad2d |
205 | void freersakey(struct RSAKey *key) { |
206 | if (key->modulus) freebn(key->modulus); |
207 | if (key->exponent) freebn(key->exponent); |
208 | if (key->private_exponent) freebn(key->private_exponent); |
dcbde236 |
209 | if (key->comment) sfree(key->comment); |
5c58ad2d |
210 | } |
85cc02bb |
211 | |
212 | /* ---------------------------------------------------------------------- |
213 | * Implementation of the ssh-rsa signing key type. |
214 | */ |
215 | |
216 | #define GET_32BIT(cp) \ |
217 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
218 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
219 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
220 | ((unsigned long)(unsigned char)(cp)[3])) |
221 | |
222 | #define PUT_32BIT(cp, value) { \ |
223 | (cp)[0] = (unsigned char)((value) >> 24); \ |
224 | (cp)[1] = (unsigned char)((value) >> 16); \ |
225 | (cp)[2] = (unsigned char)((value) >> 8); \ |
226 | (cp)[3] = (unsigned char)(value); } |
227 | |
228 | static void getstring(char **data, int *datalen, char **p, int *length) { |
229 | *p = NULL; |
230 | if (*datalen < 4) |
231 | return; |
232 | *length = GET_32BIT(*data); |
233 | *datalen -= 4; *data += 4; |
234 | if (*datalen < *length) |
235 | return; |
236 | *p = *data; |
237 | *data += *length; *datalen -= *length; |
238 | } |
239 | static Bignum getmp(char **data, int *datalen) { |
240 | char *p; |
241 | int length; |
242 | Bignum b; |
243 | |
244 | getstring(data, datalen, &p, &length); |
245 | if (!p) |
246 | return NULL; |
247 | b = bignum_from_bytes(p, length); |
248 | return b; |
249 | } |
250 | |
251 | static void *rsa2_newkey(char *data, int len) { |
252 | char *p; |
253 | int slen; |
254 | struct RSAKey *rsa; |
255 | |
256 | rsa = smalloc(sizeof(struct RSAKey)); |
257 | if (!rsa) return NULL; |
258 | getstring(&data, &len, &p, &slen); |
259 | |
45cebe79 |
260 | if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { |
85cc02bb |
261 | sfree(rsa); |
262 | return NULL; |
263 | } |
264 | rsa->exponent = getmp(&data, &len); |
265 | rsa->modulus = getmp(&data, &len); |
266 | rsa->private_exponent = NULL; |
267 | rsa->comment = NULL; |
268 | |
269 | return rsa; |
270 | } |
271 | |
272 | static void rsa2_freekey(void *key) { |
273 | struct RSAKey *rsa = (struct RSAKey *)key; |
274 | freersakey(rsa); |
275 | sfree(rsa); |
276 | } |
277 | |
278 | static char *rsa2_fmtkey(void *key) { |
279 | struct RSAKey *rsa = (struct RSAKey *)key; |
280 | char *p; |
281 | int len; |
282 | |
283 | len = rsastr_len(rsa); |
284 | p = smalloc(len); |
98f022f5 |
285 | rsastr_fmt(p, rsa); |
85cc02bb |
286 | return p; |
287 | } |
288 | |
65a22376 |
289 | static unsigned char *rsa2_public_blob(void *key, int *len) { |
290 | struct RSAKey *rsa = (struct RSAKey *)key; |
291 | int elen, mlen, bloblen; |
292 | int i; |
293 | unsigned char *blob, *p; |
294 | |
ddecd643 |
295 | elen = (bignum_bitcount(rsa->exponent)+8)/8; |
296 | mlen = (bignum_bitcount(rsa->modulus)+8)/8; |
65a22376 |
297 | |
298 | /* |
299 | * string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen. |
300 | * (three length fields, 12+7=19). |
301 | */ |
302 | bloblen = 19+elen+mlen; |
303 | blob = smalloc(bloblen); |
304 | p = blob; |
305 | PUT_32BIT(p, 7); p += 4; |
306 | memcpy(p, "ssh-rsa", 7); p += 7; |
307 | PUT_32BIT(p, elen); p += 4; |
308 | for (i = elen; i-- ;) *p++ = bignum_byte(rsa->exponent, i); |
309 | PUT_32BIT(p, mlen); p += 4; |
310 | for (i = mlen; i-- ;) *p++ = bignum_byte(rsa->modulus, i); |
311 | assert(p == blob + bloblen); |
312 | *len = bloblen; |
313 | return blob; |
314 | } |
315 | |
316 | static unsigned char *rsa2_private_blob(void *key, int *len) { |
317 | struct RSAKey *rsa = (struct RSAKey *)key; |
318 | int dlen, plen, qlen, ulen, bloblen; |
319 | int i; |
320 | unsigned char *blob, *p; |
321 | |
ddecd643 |
322 | dlen = (bignum_bitcount(rsa->private_exponent)+8)/8; |
323 | plen = (bignum_bitcount(rsa->p)+8)/8; |
324 | qlen = (bignum_bitcount(rsa->q)+8)/8; |
325 | ulen = (bignum_bitcount(rsa->iqmp)+8)/8; |
65a22376 |
326 | |
327 | /* |
328 | * mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 + |
329 | * sum of lengths. |
330 | */ |
331 | bloblen = 16+dlen+plen+qlen+ulen; |
332 | blob = smalloc(bloblen); |
333 | p = blob; |
334 | PUT_32BIT(p, dlen); p += 4; |
335 | for (i = dlen; i-- ;) *p++ = bignum_byte(rsa->private_exponent, i); |
336 | PUT_32BIT(p, plen); p += 4; |
337 | for (i = plen; i-- ;) *p++ = bignum_byte(rsa->p, i); |
338 | PUT_32BIT(p, qlen); p += 4; |
339 | for (i = qlen; i-- ;) *p++ = bignum_byte(rsa->q, i); |
340 | PUT_32BIT(p, ulen); p += 4; |
341 | for (i = ulen; i-- ;) *p++ = bignum_byte(rsa->iqmp, i); |
342 | assert(p == blob + bloblen); |
343 | *len = bloblen; |
344 | return blob; |
345 | } |
346 | |
347 | static void *rsa2_createkey(unsigned char *pub_blob, int pub_len, |
348 | unsigned char *priv_blob, int priv_len) { |
349 | struct RSAKey *rsa; |
350 | char *pb = (char *)priv_blob; |
351 | |
352 | rsa = rsa2_newkey((char *)pub_blob, pub_len); |
353 | rsa->private_exponent = getmp(&pb, &priv_len); |
354 | rsa->p = getmp(&pb, &priv_len); |
355 | rsa->q = getmp(&pb, &priv_len); |
356 | rsa->iqmp = getmp(&pb, &priv_len); |
357 | |
98f022f5 |
358 | if (!rsa_verify(rsa)) { |
359 | rsa2_freekey(rsa); |
360 | return NULL; |
361 | } |
362 | |
65a22376 |
363 | return rsa; |
364 | } |
365 | |
45cebe79 |
366 | static void *rsa2_openssh_createkey(unsigned char **blob, int *len) { |
367 | char **b = (char **)blob; |
368 | struct RSAKey *rsa; |
45cebe79 |
369 | |
370 | rsa = smalloc(sizeof(struct RSAKey)); |
371 | if (!rsa) return NULL; |
372 | rsa->comment = NULL; |
373 | |
374 | rsa->modulus = getmp(b, len); |
375 | rsa->exponent = getmp(b, len); |
376 | rsa->private_exponent = getmp(b, len); |
377 | rsa->iqmp = getmp(b, len); |
378 | rsa->p = getmp(b, len); |
379 | rsa->q = getmp(b, len); |
380 | |
381 | if (!rsa->modulus || !rsa->exponent || !rsa->private_exponent || |
382 | !rsa->iqmp || !rsa->p || !rsa->q) { |
383 | sfree(rsa->modulus); |
384 | sfree(rsa->exponent); |
385 | sfree(rsa->private_exponent); |
386 | sfree(rsa->iqmp); |
387 | sfree(rsa->p); |
388 | sfree(rsa->q); |
389 | sfree(rsa); |
390 | return NULL; |
391 | } |
392 | |
393 | return rsa; |
394 | } |
395 | |
260f3dec |
396 | static int rsa2_openssh_fmtkey(void *key, unsigned char *blob, int len) { |
ddecd643 |
397 | struct RSAKey *rsa = (struct RSAKey *)key; |
398 | int bloblen, i; |
399 | |
400 | bloblen = |
401 | ssh2_bignum_length(rsa->modulus) + |
402 | ssh2_bignum_length(rsa->exponent) + |
403 | ssh2_bignum_length(rsa->private_exponent) + |
404 | ssh2_bignum_length(rsa->iqmp) + |
405 | ssh2_bignum_length(rsa->p) + |
406 | ssh2_bignum_length(rsa->q); |
407 | |
408 | if (bloblen > len) |
409 | return bloblen; |
410 | |
411 | bloblen = 0; |
412 | #define ENC(x) \ |
413 | PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \ |
414 | for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i); |
415 | ENC(rsa->modulus); |
416 | ENC(rsa->exponent); |
417 | ENC(rsa->private_exponent); |
418 | ENC(rsa->iqmp); |
419 | ENC(rsa->p); |
420 | ENC(rsa->q); |
421 | |
422 | return bloblen; |
423 | } |
424 | |
85cc02bb |
425 | static char *rsa2_fingerprint(void *key) { |
426 | struct RSAKey *rsa = (struct RSAKey *)key; |
427 | struct MD5Context md5c; |
428 | unsigned char digest[16], lenbuf[4]; |
429 | char buffer[16*3+40]; |
430 | char *ret; |
431 | int numlen, i; |
432 | |
433 | MD5Init(&md5c); |
434 | MD5Update(&md5c, "\0\0\0\7ssh-rsa", 11); |
435 | |
436 | #define ADD_BIGNUM(bignum) \ |
ddecd643 |
437 | numlen = (bignum_bitcount(bignum)+8)/8; \ |
85cc02bb |
438 | PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \ |
439 | for (i = numlen; i-- ;) { \ |
440 | unsigned char c = bignum_byte(bignum, i); \ |
441 | MD5Update(&md5c, &c, 1); \ |
442 | } |
443 | ADD_BIGNUM(rsa->exponent); |
444 | ADD_BIGNUM(rsa->modulus); |
445 | #undef ADD_BIGNUM |
446 | |
447 | MD5Final(digest, &md5c); |
448 | |
ddecd643 |
449 | sprintf(buffer, "ssh-rsa %d ", bignum_bitcount(rsa->modulus)); |
85cc02bb |
450 | for (i = 0; i < 16; i++) |
451 | sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]); |
452 | ret = smalloc(strlen(buffer)+1); |
453 | if (ret) |
454 | strcpy(ret, buffer); |
455 | return ret; |
456 | } |
457 | |
458 | /* |
459 | * This is the magic ASN.1/DER prefix that goes in the decoded |
460 | * signature, between the string of FFs and the actual SHA hash |
96a73db9 |
461 | * value. The meaning of it is: |
85cc02bb |
462 | * |
463 | * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself |
464 | * |
465 | * 30 21 -- a constructed SEQUENCE of length 0x21 |
466 | * 30 09 -- a constructed sub-SEQUENCE of length 9 |
467 | * 06 05 -- an object identifier, length 5 |
96a73db9 |
468 | * 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 } |
469 | * (the 1,3 comes from 0x2B = 43 = 40*1+3) |
85cc02bb |
470 | * 05 00 -- NULL |
471 | * 04 14 -- a primitive OCTET STRING of length 0x14 |
472 | * [0x14 bytes of hash data follows] |
96a73db9 |
473 | * |
474 | * The object id in the middle there is listed as `id-sha1' in |
475 | * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the |
476 | * ASN module for PKCS #1) and its expanded form is as follows: |
477 | * |
478 | * id-sha1 OBJECT IDENTIFIER ::= { |
479 | * iso(1) identified-organization(3) oiw(14) secsig(3) |
480 | * algorithms(2) 26 } |
85cc02bb |
481 | */ |
482 | static unsigned char asn1_weird_stuff[] = { |
483 | 0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2B, |
484 | 0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14, |
485 | }; |
486 | |
d8770b12 |
487 | #define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) ) |
488 | |
85cc02bb |
489 | static int rsa2_verifysig(void *key, char *sig, int siglen, |
490 | char *data, int datalen) { |
491 | struct RSAKey *rsa = (struct RSAKey *)key; |
492 | Bignum in, out; |
493 | char *p; |
494 | int slen; |
495 | int bytes, i, j, ret; |
496 | unsigned char hash[20]; |
497 | |
498 | getstring(&sig, &siglen, &p, &slen); |
499 | if (!p || slen != 7 || memcmp(p, "ssh-rsa", 7)) { |
500 | return 0; |
501 | } |
502 | in = getmp(&sig, &siglen); |
503 | out = modpow(in, rsa->exponent, rsa->modulus); |
504 | freebn(in); |
505 | |
506 | ret = 1; |
507 | |
ddecd643 |
508 | bytes = bignum_bitcount(rsa->modulus) / 8; |
85cc02bb |
509 | /* Top (partial) byte should be zero. */ |
510 | if (bignum_byte(out, bytes-1) != 0) |
511 | ret = 0; |
512 | /* First whole byte should be 1. */ |
513 | if (bignum_byte(out, bytes-2) != 1) |
514 | ret = 0; |
515 | /* Most of the rest should be FF. */ |
d8770b12 |
516 | for (i = bytes-3; i >= 20 + ASN1_LEN; i--) { |
85cc02bb |
517 | if (bignum_byte(out, i) != 0xFF) |
518 | ret = 0; |
519 | } |
520 | /* Then we expect to see the asn1_weird_stuff. */ |
d8770b12 |
521 | for (i = 20 + ASN1_LEN - 1, j=0; i >= 20; i--,j++) { |
85cc02bb |
522 | if (bignum_byte(out, i) != asn1_weird_stuff[j]) |
523 | ret = 0; |
524 | } |
525 | /* Finally, we expect to see the SHA-1 hash of the signed data. */ |
526 | SHA_Simple(data, datalen, hash); |
527 | for (i = 19, j=0; i >= 0; i--,j++) { |
528 | if (bignum_byte(out, i) != hash[j]) |
529 | ret = 0; |
530 | } |
531 | |
532 | return ret; |
533 | } |
534 | |
65a22376 |
535 | unsigned char *rsa2_sign(void *key, char *data, int datalen, int *siglen) { |
536 | struct RSAKey *rsa = (struct RSAKey *)key; |
537 | unsigned char *bytes; |
538 | int nbytes; |
539 | unsigned char hash[20]; |
540 | Bignum in, out; |
541 | int i, j; |
542 | |
543 | SHA_Simple(data, datalen, hash); |
544 | |
ddecd643 |
545 | nbytes = (bignum_bitcount(rsa->modulus)-1) / 8; |
65a22376 |
546 | bytes = smalloc(nbytes); |
547 | |
548 | bytes[0] = 1; |
d8770b12 |
549 | for (i = 1; i < nbytes-20-ASN1_LEN; i++) |
65a22376 |
550 | bytes[i] = 0xFF; |
d8770b12 |
551 | for (i = nbytes-20-ASN1_LEN, j=0; i < nbytes-20; i++,j++) |
65a22376 |
552 | bytes[i] = asn1_weird_stuff[j]; |
553 | for (i = nbytes-20, j=0; i < nbytes; i++,j++) |
554 | bytes[i] = hash[j]; |
555 | |
556 | in = bignum_from_bytes(bytes, nbytes); |
557 | sfree(bytes); |
558 | |
559 | out = modpow(in, rsa->private_exponent, rsa->modulus); |
560 | freebn(in); |
561 | |
ddecd643 |
562 | nbytes = (bignum_bitcount(out)+7)/8; |
65a22376 |
563 | bytes = smalloc(4+7+4+nbytes); |
564 | PUT_32BIT(bytes, 7); |
565 | memcpy(bytes+4, "ssh-rsa", 7); |
566 | PUT_32BIT(bytes+4+7, nbytes); |
567 | for (i = 0; i < nbytes; i++) |
568 | bytes[4+7+4+i] = bignum_byte(out, nbytes-1-i); |
569 | freebn(out); |
570 | |
571 | *siglen = 4+7+4+nbytes; |
572 | return bytes; |
85cc02bb |
573 | } |
574 | |
65a22376 |
575 | const struct ssh_signkey ssh_rsa = { |
85cc02bb |
576 | rsa2_newkey, |
577 | rsa2_freekey, |
578 | rsa2_fmtkey, |
65a22376 |
579 | rsa2_public_blob, |
580 | rsa2_private_blob, |
581 | rsa2_createkey, |
45cebe79 |
582 | rsa2_openssh_createkey, |
ddecd643 |
583 | rsa2_openssh_fmtkey, |
85cc02bb |
584 | rsa2_fingerprint, |
585 | rsa2_verifysig, |
586 | rsa2_sign, |
587 | "ssh-rsa", |
588 | "rsa2" |
589 | }; |