1 /***************************************************************************
3 * Part II Project, "A secure, private IP network"
4 * Stephen Early <sde1000@cam.ac.uk>
9 * Description: RSA signature making and checking functions
11 * Copyright: (C) Stephen Early 1995
15 * $Date: 1996/05/16 18:40:14 $
19 ***************************************************************************/
22 * Revision 1.1 1996/05/16 18:40:14 sde1000
32 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
36 struct rsaprivkey_if ops
;
43 struct rsapubkey_if ops
;
48 /* Sign data. NB data must be smaller than modulus */
50 static char *hexchars
="0123456789abcdef";
52 static string_t
rsa_sign(void *sst
, uint8_t *data
, uint32_t datalen
)
54 struct rsapriv
*st
=sst
;
63 msize
=mpz_sizeinbase(&st
->n
, 16);
67 for (i
=0; i
<datalen
; i
++) {
68 buff
[4+i
*2]=hexchars
[(data
[i
]&0xf0)>>4];
69 buff
[5+i
*2]=hexchars
[data
[i
]&0xf];
73 for (i
=datalen
*2+4; i
<msize
; i
++)
78 mpz_set_str(&a
, buff
, 16);
80 mpz_powm(&b
, &a
, &st
->d
, &st
->n
);
82 signature
=write_mpstring(&b
);
89 static bool_t
rsa_sig_check(void *sst
, uint8_t *data
, uint32_t datalen
,
92 struct rsapub
*st
=sst
;
102 msize
=mpz_sizeinbase(&st
->n
, 16);
106 for (i
=0; i
<datalen
; i
++) {
107 buff
[4+i
*2]=hexchars
[(data
[i
]&0xf0)>>4];
108 buff
[5+i
*2]=hexchars
[data
[i
]&0xf];
112 for (i
=datalen
*2+4; i
<msize
; i
++)
117 mpz_set_str(&a
, buff
, 16);
119 mpz_set_str(&b
, signature
, 16);
121 mpz_powm(&c
, &b
, &st
->e
, &st
->n
);
123 ok
=(mpz_cmp(&a
, &c
)==0);
132 static list_t
*rsapub_apply(closure_t
*self
, struct cloc loc
, dict_t
*context
,
139 st
=safe_malloc(sizeof(*st
),"rsapub_apply");
140 st
->cl
.description
="rsapub";
141 st
->cl
.type
=CL_RSAPUBKEY
;
143 st
->cl
.interface
=&st
->ops
;
145 st
->ops
.check
=rsa_sig_check
;
150 if (i
->type
!=t_string
) {
151 cfgfatal(i
->loc
,"rsa-public","first argument must be a string");
154 if (mpz_init_set_str(&st
->e
,e
,10)!=0) {
155 cfgfatal(i
->loc
,"rsa-public","encryption key \"%s\" is not a "
156 "decimal number string\n",e
);
159 cfgfatal(loc
,"rsa-public","you must provide an encryption key\n");
164 if (i
->type
!=t_string
) {
165 cfgfatal(i
->loc
,"rsa-public","second argument must be a string");
168 if (mpz_init_set_str(&st
->n
,n
,10)!=0) {
169 cfgfatal(i
->loc
,"rsa-public","modulus \"%s\" is not a decimal "
170 "number string\n",n
);
173 cfgfatal(loc
,"rsa-public","you must provide a modulus\n");
175 return new_closure(&st
->cl
);
178 static uint32_t keyfile_get_int(FILE *f
)
188 static uint16_t keyfile_get_short(FILE *f
)
196 static list_t
*rsapriv_apply(closure_t
*self
, struct cloc loc
, dict_t
*context
,
206 MP_INT e
,sig
,plain
,check
;
208 st
=safe_malloc(sizeof(*st
),"rsapriv_apply");
209 st
->cl
.description
="rsapriv";
210 st
->cl
.type
=CL_RSAPRIVKEY
;
212 st
->cl
.interface
=&st
->ops
;
214 st
->ops
.sign
=rsa_sign
;
217 /* Argument is filename pointing to SSH1 private key file */
220 if (i
->type
!=t_string
) {
221 cfgfatal(i
->loc
,"rsa-public","first argument must be a string");
223 filename
=i
->data
.string
;
225 filename
=""; /* Make compiler happy */
226 cfgfatal(loc
,"rsa-private","you must provide a filename\n");
229 f
=fopen(filename
,"rb");
231 fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"",
232 loc
.file
,loc
.line
,filename
);
235 /* Check that the ID string is correct */
236 length
=strlen(AUTHFILE_ID_STRING
)+1;
237 b
=safe_malloc(length
,"rsapriv_apply");
238 if (fread(b
,length
,1,f
)!=1 || memcmp(b
,AUTHFILE_ID_STRING
,length
)!=0) {
239 cfgfatal(loc
,"rsa-private","file \"%s\" is not a "
240 "SSH1 private keyfile\n",filename
);
244 cipher_type
=fgetc(f
);
245 keyfile_get_int(f
); /* "Reserved data" */
246 if (cipher_type
!= 0) {
247 cfgfatal(loc
,"rsa-private","we don't support encrypted keyfiles\n");
250 /* Read the public key */
251 keyfile_get_int(f
); /* Not sure what this is */
252 length
=(keyfile_get_short(f
)+7)/8;
254 cfgfatal(loc
,"rsa-private","implausible length %ld for modulus\n",
257 b
=safe_malloc(length
,"rsapriv_apply");
258 if (fread(b
,length
,1,f
) != 1) {
259 cfgfatal(loc
,"rsa-private","error reading modulus\n");
262 read_mpbin(&st
->n
,b
,length
);
264 length
=(keyfile_get_short(f
)+7)/8;
266 cfgfatal(loc
,"rsa-private","implausible length %ld for e\n",length
);
268 b
=safe_malloc(length
,"rsapriv_apply");
269 if (fread(b
,length
,1,f
)!=1) {
270 cfgfatal(loc
,"rsa-private","error reading e\n");
273 read_mpbin(&e
,b
,length
);
276 length
=keyfile_get_int(f
);
278 cfgfatal(loc
,"rsa-private","implausibly long (%ld) key comment\n",
281 c
=safe_malloc(length
+1,"rsapriv_apply");
282 if (fread(c
,length
,1,f
)!=1) {
283 cfgfatal(loc
,"rsa-private","error reading key comment\n");
287 /* Check that the next two pairs of characters are identical - the
288 keyfile is not encrypted, so they should be */
289 if (keyfile_get_short(f
) != keyfile_get_short(f
)) {
290 cfgfatal(loc
,"rsa-private","corrupt keyfile\n");
294 length
=(keyfile_get_short(f
)+7)/8;
296 cfgfatal(loc
,"rsa-private","implausibly long (%ld) decryption key\n",
299 b
=safe_malloc(length
,"rsapriv_apply");
300 if (fread(b
,length
,1,f
)!=1) {
301 cfgfatal(loc
,"rsa-private","error reading decryption key\n");
304 read_mpbin(&st
->d
,b
,length
);
308 fatal_perror("rsa-private (%s:%d): fclose",loc
.file
,loc
.line
);
311 /* Now do trial signature/check to make sure it's a real keypair:
312 sign the comment string! */
316 read_mpbin(&plain
,c
,strlen(c
));
317 mpz_powm(&sig
, &plain
, &st
->d
, &st
->n
);
318 mpz_powm(&check
, &sig
, &e
, &st
->n
);
319 if (mpz_cmp(&plain
,&check
)!=0) {
320 cfgfatal(loc
,"rsa-private","file \"%s\" does not contain a "
321 "valid RSA key!\n",filename
);
330 return new_closure(&st
->cl
);
333 init_module rsa_module
;
334 void rsa_module(dict_t
*dict
)
336 add_closure(dict
,"rsa-private",rsapriv_apply
);
337 add_closure(dict
,"rsa-public",rsapub_apply
);