1 /* This file is part of secnet, and is distributed under the terms of
2 the GNU General Public License version 2 or later.
4 Copyright (C) 1995-2002 Stephen Early
5 Copyright (C) 2001 Simon Tatham
6 Copyright (C) 2002 Ian Jackson
15 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
17 #define mpp(s,n) do { char *p = mpz_get_str(NULL,16,n); printf("%s 0x%sL\n", s, p); free(p); } while (0)
21 struct rsaprivkey_if ops
;
30 struct rsapubkey_if ops
;
35 /* Sign data. NB data must be smaller than modulus */
37 static const char *hexchars
="0123456789abcdef";
39 static void emsa_pkcs1(MP_INT
*n
, MP_INT
*m
,
40 const uint8_t *data
, int32_t datalen
)
45 /* RSA PKCS#1 v1.5 signature padding:
47 * <------------ msize hex digits ---------->
49 * 00 01 ff ff .... ff ff 00 vv vv vv .... vv
53 * = datalen*2 hex digits
55 * NB that according to PKCS#1 v1.5 we're supposed to include a
56 * hash function OID in the data. We don't do that (because we
57 * don't have the hash function OID to hand here), thus violating
58 * the spec in a way that affects interop but not security.
63 msize
=mpz_sizeinbase(n
, 16);
65 if (datalen
*2+6>=msize
) {
66 fatal("rsa_sign: message too big");
71 for (i
=0; i
<datalen
; i
++) {
72 buff
[msize
+(-datalen
+i
)*2]=hexchars
[(data
[i
]&0xf0)>>4];
73 buff
[msize
+(-datalen
+i
)*2+1]=hexchars
[data
[i
]&0xf];
76 buff
[msize
-datalen
*2-2]= '0';
77 buff
[msize
-datalen
*2-1]= '0';
79 for (i
=4; i
<msize
-datalen
*2-2; i
++)
84 mpz_set_str(m
, buff
, 16);
87 static string_t
rsa_sign(void *sst
, uint8_t *data
, int32_t datalen
)
89 struct rsapriv
*st
=sst
;
90 MP_INT a
, b
, u
, v
, tmp
, tmp2
;
96 /* Construct the message representative. */
97 emsa_pkcs1(&st
->n
, &a
, data
, datalen
);
100 * Produce an RSA signature (a^d mod n) using the Chinese
101 * Remainder Theorem. We compute:
103 * u = a^dp mod p (== a^d mod p, since dp == d mod (p-1))
104 * v = a^dq mod q (== a^d mod q, similarly)
106 * We also know w == iqmp * q, which has the property that w ==
107 * 0 mod q and w == 1 mod p. So (1-w) has the reverse property
108 * (congruent to 0 mod p and to 1 mod q). Hence we now compute
110 * b = w * u + (1-w) * v
113 * so that b is congruent to a^d both mod p and mod q. Hence b,
114 * reduced mod n, is the required signature.
121 mpz_powm(&u
, &a
, &st
->dp
, &st
->p
);
122 mpz_powm(&v
, &a
, &st
->dq
, &st
->q
);
123 mpz_sub(&tmp
, &u
, &v
);
124 mpz_mul(&tmp2
, &tmp
, &st
->w
);
125 mpz_add(&tmp
, &tmp2
, &v
);
126 mpz_mod(&b
, &tmp
, &st
->n
);
133 signature
=write_mpstring(&b
);
140 static rsa_checksig_fn rsa_sig_check
;
141 static bool_t
rsa_sig_check(void *sst
, uint8_t *data
, int32_t datalen
,
144 struct rsapub
*st
=sst
;
152 emsa_pkcs1(&st
->n
, &a
, data
, datalen
);
154 mpz_set_str(&b
, signature
, 16);
156 mpz_powm(&c
, &b
, &st
->e
, &st
->n
);
158 ok
=(mpz_cmp(&a
, &c
)==0);
167 static list_t
*rsapub_apply(closure_t
*self
, struct cloc loc
, dict_t
*context
,
174 st
=safe_malloc(sizeof(*st
),"rsapub_apply");
175 st
->cl
.description
="rsapub";
176 st
->cl
.type
=CL_RSAPUBKEY
;
178 st
->cl
.interface
=&st
->ops
;
180 st
->ops
.check
=rsa_sig_check
;
185 if (i
->type
!=t_string
) {
186 cfgfatal(i
->loc
,"rsa-public","first argument must be a string\n");
189 if (mpz_init_set_str(&st
->e
,e
,10)!=0) {
190 cfgfatal(i
->loc
,"rsa-public","encryption key \"%s\" is not a "
191 "decimal number string\n",e
);
194 cfgfatal(loc
,"rsa-public","you must provide an encryption key\n");
199 if (i
->type
!=t_string
) {
200 cfgfatal(i
->loc
,"rsa-public","second argument must be a string\n");
203 if (mpz_init_set_str(&st
->n
,n
,10)!=0) {
204 cfgfatal(i
->loc
,"rsa-public","modulus \"%s\" is not a decimal "
205 "number string\n",n
);
208 cfgfatal(loc
,"rsa-public","you must provide a modulus\n");
210 return new_closure(&st
->cl
);
213 static uint32_t keyfile_get_int(struct cloc loc
, FILE *f
)
220 cfgfile_postreadcheck(loc
,f
);
224 static uint16_t keyfile_get_short(struct cloc loc
, FILE *f
)
229 cfgfile_postreadcheck(loc
,f
);
233 static list_t
*rsapriv_apply(closure_t
*self
, struct cloc loc
, dict_t
*context
,
243 MP_INT e
,d
,iqmp
,tmp
,tmp2
,tmp3
;
246 st
=safe_malloc(sizeof(*st
),"rsapriv_apply");
247 st
->cl
.description
="rsapriv";
248 st
->cl
.type
=CL_RSAPRIVKEY
;
250 st
->cl
.interface
=&st
->ops
;
252 st
->ops
.sign
=rsa_sign
;
255 /* Argument is filename pointing to SSH1 private key file */
258 if (i
->type
!=t_string
) {
259 cfgfatal(i
->loc
,"rsa-public","first argument must be a string\n");
261 filename
=i
->data
.string
;
263 filename
=NULL
; /* Make compiler happy */
264 cfgfatal(loc
,"rsa-private","you must provide a filename\n");
267 f
=fopen(filename
,"rb");
269 if (just_check_config
) {
270 Message(M_WARNING
,"rsa-private (%s:%d): cannot open keyfile "
271 "\"%s\"; assuming it's valid while we check the "
272 "rest of the configuration\n",loc
.file
,loc
.line
,filename
);
275 fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"",
276 loc
.file
,loc
.line
,filename
);
280 /* Check that the ID string is correct */
281 length
=strlen(AUTHFILE_ID_STRING
)+1;
282 b
=safe_malloc(length
,"rsapriv_apply");
283 if (fread(b
,length
,1,f
)!=1 || memcmp(b
,AUTHFILE_ID_STRING
,length
)!=0) {
284 cfgfatal_maybefile(f
,loc
,"rsa-private","failed to read magic ID"
285 " string from SSH1 private keyfile \"%s\"\n",
290 cipher_type
=fgetc(f
);
291 keyfile_get_int(loc
,f
); /* "Reserved data" */
292 if (cipher_type
!= 0) {
293 cfgfatal(loc
,"rsa-private","we don't support encrypted keyfiles\n");
296 /* Read the public key */
297 keyfile_get_int(loc
,f
); /* Not sure what this is */
298 length
=(keyfile_get_short(loc
,f
)+7)/8;
300 cfgfatal(loc
,"rsa-private","implausible length %ld for modulus\n",
303 b
=safe_malloc(length
,"rsapriv_apply");
304 if (fread(b
,length
,1,f
) != 1) {
305 cfgfatal_maybefile(f
,loc
,"rsa-private","error reading modulus\n");
308 read_mpbin(&st
->n
,b
,length
);
310 length
=(keyfile_get_short(loc
,f
)+7)/8;
312 cfgfatal(loc
,"rsa-private","implausible length %ld for e\n",length
);
314 b
=safe_malloc(length
,"rsapriv_apply");
315 if (fread(b
,length
,1,f
)!=1) {
316 cfgfatal_maybefile(f
,loc
,"rsa-private","error reading e\n");
319 read_mpbin(&e
,b
,length
);
322 length
=keyfile_get_int(loc
,f
);
324 cfgfatal(loc
,"rsa-private","implausibly long (%ld) key comment\n",
327 c
=safe_malloc(length
+1,"rsapriv_apply");
328 if (fread(c
,length
,1,f
)!=1) {
329 cfgfatal_maybefile(f
,loc
,"rsa-private","error reading key comment\n");
333 /* Check that the next two pairs of characters are identical - the
334 keyfile is not encrypted, so they should be */
336 if (keyfile_get_short(loc
,f
) != keyfile_get_short(loc
,f
)) {
337 cfgfatal(loc
,"rsa-private","corrupt keyfile\n");
341 length
=(keyfile_get_short(loc
,f
)+7)/8;
343 cfgfatal(loc
,"rsa-private","implausibly long (%ld) decryption key\n",
346 b
=safe_malloc(length
,"rsapriv_apply");
347 if (fread(b
,length
,1,f
)!=1) {
348 cfgfatal_maybefile(f
,loc
,"rsa-private",
349 "error reading decryption key\n");
352 read_mpbin(&d
,b
,length
);
354 /* Read iqmp (inverse of q mod p) */
355 length
=(keyfile_get_short(loc
,f
)+7)/8;
357 cfgfatal(loc
,"rsa-private","implausibly long (%ld)"
358 " iqmp auxiliary value\n", length
);
360 b
=safe_malloc(length
,"rsapriv_apply");
361 if (fread(b
,length
,1,f
)!=1) {
362 cfgfatal_maybefile(f
,loc
,"rsa-private",
363 "error reading decryption key\n");
366 read_mpbin(&iqmp
,b
,length
);
368 /* Read q (the smaller of the two primes) */
369 length
=(keyfile_get_short(loc
,f
)+7)/8;
371 cfgfatal(loc
,"rsa-private","implausibly long (%ld) q value\n",
374 b
=safe_malloc(length
,"rsapriv_apply");
375 if (fread(b
,length
,1,f
)!=1) {
376 cfgfatal_maybefile(f
,loc
,"rsa-private",
377 "error reading q value\n");
380 read_mpbin(&st
->q
,b
,length
);
382 /* Read p (the larger of the two primes) */
383 length
=(keyfile_get_short(loc
,f
)+7)/8;
385 cfgfatal(loc
,"rsa-private","implausibly long (%ld) p value\n",
388 b
=safe_malloc(length
,"rsapriv_apply");
389 if (fread(b
,length
,1,f
)!=1) {
390 cfgfatal_maybefile(f
,loc
,"rsa-private",
391 "error reading p value\n");
394 read_mpbin(&st
->p
,b
,length
);
398 fatal_perror("rsa-private (%s:%d): fclose",loc
.file
,loc
.line
);
402 * Now verify the validity of the key, and set up the auxiliary
403 * values for fast CRT signing.
410 if (i
&& i
->type
==t_bool
&& i
->data
.bool==False
) {
411 Message(M_INFO
,"rsa-private (%s:%d): skipping RSA key validity "
412 "check\n",loc
.file
,loc
.line
);
414 /* Verify that p*q is equal to n. */
415 mpz_mul(&tmp
, &st
->p
, &st
->q
);
416 if (mpz_cmp(&tmp
, &st
->n
) != 0)
420 * Verify that d*e is congruent to 1 mod (p-1), and mod
421 * (q-1). This is equivalent to it being congruent to 1 mod
422 * lambda(n) = lcm(p-1,q-1). The usual `textbook' condition,
423 * that d e == 1 (mod (p-1)(q-1)) is sufficient, but not
424 * actually necessary.
426 mpz_mul(&tmp
, &d
, &e
);
427 mpz_sub_ui(&tmp2
, &st
->p
, 1);
428 mpz_mod(&tmp3
, &tmp
, &tmp2
);
429 if (mpz_cmp_si(&tmp3
, 1) != 0)
431 mpz_sub_ui(&tmp2
, &st
->q
, 1);
432 mpz_mod(&tmp3
, &tmp
, &tmp2
);
433 if (mpz_cmp_si(&tmp3
, 1) != 0)
436 /* Verify that q*iqmp is congruent to 1 mod p. */
437 mpz_mul(&tmp
, &st
->q
, &iqmp
);
438 mpz_mod(&tmp2
, &tmp
, &st
->p
);
439 if (mpz_cmp_si(&tmp2
, 1) != 0)
442 /* Now we know the key is valid (or we don't care). */
446 * Now we compute auxiliary values dp, dq and w to allow us
447 * to use the CRT optimisation when signing.
449 * dp == d mod (p-1) so that a^dp == a^d mod p, for all a
450 * dq == d mod (q-1) similarly mod q
451 * w == iqmp * q so that w == 0 mod q, and w == 1 mod p
456 mpz_sub_ui(&tmp
, &st
->p
, 1);
457 mpz_mod(&st
->dp
, &d
, &tmp
);
458 mpz_sub_ui(&tmp
, &st
->q
, 1);
459 mpz_mod(&st
->dq
, &d
, &tmp
);
460 mpz_mul(&st
->w
, &iqmp
, &st
->q
);
464 cfgfatal(loc
,"rsa-private","file \"%s\" does not contain a "
465 "valid RSA key!\n",filename
);
477 return new_closure(&st
->cl
);
480 void rsa_module(dict_t
*dict
)
482 add_closure(dict
,"rsa-private",rsapriv_apply
);
483 add_closure(dict
,"rsa-public",rsapub_apply
);