2 * RSA implementation just sufficient for ssh client-side
5 * Rewritten for more speed by Joris van Rantwijk, Jun 1999.
15 int makekey(unsigned char *data
, struct RSAKey
*result
,
16 unsigned char **keystr
, int order
) {
17 unsigned char *p
= data
;
23 result
->bits
= (result
->bits
<< 8) + *p
++;
28 * order=0 means exponent then modulus (the keys sent by the
29 * server). order=1 means modulus then exponent (the keys
30 * stored in a keyfile).
34 p
+= ssh1_read_bignum(p
, result ?
&result
->exponent
: NULL
);
36 result
->bytes
= (((p
[0] << 8) + p
[1]) + 7) / 8;
37 if (keystr
) *keystr
= p
+2;
38 p
+= ssh1_read_bignum(p
, result ?
&result
->modulus
: NULL
);
40 p
+= ssh1_read_bignum(p
, result ?
&result
->exponent
: NULL
);
45 int makeprivate(unsigned char *data
, struct RSAKey
*result
) {
46 return ssh1_read_bignum(data
, &result
->private_exponent
);
49 void rsaencrypt(unsigned char *data
, int length
, struct RSAKey
*key
) {
54 memmove(data
+key
->bytes
-length
, data
, length
);
58 for (i
= 2; i
< key
->bytes
-length
-1; i
++) {
60 data
[i
] = random_byte();
61 } while (data
[i
] == 0);
63 data
[key
->bytes
-length
-1] = 0;
65 b1
= bignum_from_bytes(data
, key
->bytes
);
67 b2
= modpow(b1
, key
->exponent
, key
->modulus
);
70 for (i
=key
->bytes
; i
-- ;) {
71 *p
++ = bignum_byte(b2
, i
);
78 Bignum
rsadecrypt(Bignum input
, struct RSAKey
*key
) {
80 ret
= modpow(input
, key
->private_exponent
, key
->modulus
);
84 int rsastr_len(struct RSAKey
*key
) {
90 mdlen
= (ssh1_bignum_bitcount(md
)+15) / 16;
91 exlen
= (ssh1_bignum_bitcount(ex
)+15) / 16;
92 return 4 * (mdlen
+exlen
) + 20;
95 void rsastr_fmt(char *str
, struct RSAKey
*key
) {
97 int len
= 0, i
, nibbles
;
98 static const char hex
[] = "0123456789abcdef";
103 len
+= sprintf(str
+len
, "0x");
105 nibbles
= (3 + ssh1_bignum_bitcount(ex
))/4; if (nibbles
<1) nibbles
=1;
106 for (i
=nibbles
; i
-- ;)
107 str
[len
++] = hex
[(bignum_byte(ex
, i
/2) >> (4*(i
%2))) & 0xF];
109 len
+= sprintf(str
+len
, ",0x");
111 nibbles
= (3 + ssh1_bignum_bitcount(md
))/4; if (nibbles
<1) nibbles
=1;
112 for (i
=nibbles
; i
-- ;)
113 str
[len
++] = hex
[(bignum_byte(md
, i
/2) >> (4*(i
%2))) & 0xF];
119 * Generate a fingerprint string for the key. Compatible with the
120 * OpenSSH fingerprint code.
122 void rsa_fingerprint(char *str
, int len
, struct RSAKey
*key
) {
123 struct MD5Context md5c
;
124 unsigned char digest
[16];
125 char buffer
[16*3+40];
129 numlen
= ssh1_bignum_length(key
->modulus
) - 2;
130 for (i
= numlen
; i
-- ;) {
131 unsigned char c
= bignum_byte(key
->modulus
, i
);
132 MD5Update(&md5c
, &c
, 1);
134 numlen
= ssh1_bignum_length(key
->exponent
) - 2;
135 for (i
= numlen
; i
-- ;) {
136 unsigned char c
= bignum_byte(key
->exponent
, i
);
137 MD5Update(&md5c
, &c
, 1);
139 MD5Final(digest
, &md5c
);
141 sprintf(buffer
, "%d ", ssh1_bignum_bitcount(key
->modulus
));
142 for (i
= 0; i
< 16; i
++)
143 sprintf(buffer
+strlen(buffer
), "%s%02x", i?
":":"", digest
[i
]);
144 strncpy(str
, buffer
, len
); str
[len
-1] = '\0';
146 if (key
->comment
&& slen
< len
-1) {
148 strncpy(str
+slen
+1, key
->comment
, len
-slen
-1);
153 void freersakey(struct RSAKey
*key
) {
154 if (key
->modulus
) freebn(key
->modulus
);
155 if (key
->exponent
) freebn(key
->exponent
);
156 if (key
->private_exponent
) freebn(key
->private_exponent
);
157 if (key
->comment
) sfree(key
->comment
);
160 /* ----------------------------------------------------------------------
161 * Implementation of the ssh-rsa signing key type.
164 #define GET_32BIT(cp) \
165 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
166 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
167 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
168 ((unsigned long)(unsigned char)(cp)[3]))
170 #define PUT_32BIT(cp, value) { \
171 (cp)[0] = (unsigned char)((value) >> 24); \
172 (cp)[1] = (unsigned char)((value) >> 16); \
173 (cp)[2] = (unsigned char)((value) >> 8); \
174 (cp)[3] = (unsigned char)(value); }
176 static void getstring(char **data
, int *datalen
, char **p
, int *length
) {
180 *length
= GET_32BIT(*data
);
181 *datalen
-= 4; *data
+= 4;
182 if (*datalen
< *length
)
185 *data
+= *length
; *datalen
-= *length
;
187 static Bignum
getmp(char **data
, int *datalen
) {
192 getstring(data
, datalen
, &p
, &length
);
195 b
= bignum_from_bytes(p
, length
);
199 static void *rsa2_newkey(char *data
, int len
) {
204 rsa
= smalloc(sizeof(struct RSAKey
));
205 if (!rsa
) return NULL
;
206 getstring(&data
, &len
, &p
, &slen
);
208 if (!p
|| memcmp(p
, "ssh-rsa", 7)) {
212 rsa
->exponent
= getmp(&data
, &len
);
213 rsa
->modulus
= getmp(&data
, &len
);
214 rsa
->private_exponent
= NULL
;
220 static void rsa2_freekey(void *key
) {
221 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
226 static char *rsa2_fmtkey(void *key
) {
227 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
231 len
= rsastr_len(rsa
);
237 static char *rsa2_fingerprint(void *key
) {
238 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
239 struct MD5Context md5c
;
240 unsigned char digest
[16], lenbuf
[4];
241 char buffer
[16*3+40];
246 MD5Update(&md5c
, "\0\0\0\7ssh-rsa", 11);
248 #define ADD_BIGNUM(bignum) \
249 numlen = (ssh1_bignum_bitcount(bignum)+8)/8; \
250 PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \
251 for (i = numlen; i-- ;) { \
252 unsigned char c = bignum_byte(bignum, i); \
253 MD5Update(&md5c, &c, 1); \
255 ADD_BIGNUM(rsa
->exponent
);
256 ADD_BIGNUM(rsa
->modulus
);
259 MD5Final(digest
, &md5c
);
261 sprintf(buffer
, "%d ", ssh1_bignum_bitcount(rsa
->modulus
));
262 for (i
= 0; i
< 16; i
++)
263 sprintf(buffer
+strlen(buffer
), "%s%02x", i?
":":"", digest
[i
]);
264 ret
= smalloc(strlen(buffer
)+1);
271 * This is the magic ASN.1/DER prefix that goes in the decoded
272 * signature, between the string of FFs and the actual SHA hash
273 * value. As closely as I can tell, the meaning of it is:
275 * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself
277 * 30 21 -- a constructed SEQUENCE of length 0x21
278 * 30 09 -- a constructed sub-SEQUENCE of length 9
279 * 06 05 -- an object identifier, length 5
282 * 04 14 -- a primitive OCTET STRING of length 0x14
283 * [0x14 bytes of hash data follows]
285 static unsigned char asn1_weird_stuff
[] = {
286 0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2B,
287 0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14,
290 static int rsa2_verifysig(void *key
, char *sig
, int siglen
,
291 char *data
, int datalen
) {
292 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
296 int bytes
, i
, j
, ret
;
297 unsigned char hash
[20];
299 getstring(&sig
, &siglen
, &p
, &slen
);
300 if (!p
|| slen
!= 7 || memcmp(p
, "ssh-rsa", 7)) {
303 in
= getmp(&sig
, &siglen
);
304 out
= modpow(in
, rsa
->exponent
, rsa
->modulus
);
309 bytes
= ssh1_bignum_bitcount(rsa
->modulus
) / 8;
310 /* Top (partial) byte should be zero. */
311 if (bignum_byte(out
, bytes
-1) != 0)
313 /* First whole byte should be 1. */
314 if (bignum_byte(out
, bytes
-2) != 1)
316 /* Most of the rest should be FF. */
317 for (i
= bytes
-3; i
>= 20 + sizeof(asn1_weird_stuff
); i
--) {
318 if (bignum_byte(out
, i
) != 0xFF)
321 /* Then we expect to see the asn1_weird_stuff. */
322 for (i
= 20 + sizeof(asn1_weird_stuff
) - 1, j
=0; i
>= 20; i
--,j
++) {
323 if (bignum_byte(out
, i
) != asn1_weird_stuff
[j
])
326 /* Finally, we expect to see the SHA-1 hash of the signed data. */
327 SHA_Simple(data
, datalen
, hash
);
328 for (i
= 19, j
=0; i
>= 0; i
--,j
++) {
329 if (bignum_byte(out
, i
) != hash
[j
])
336 int rsa2_sign(void *key
, char *sig
, int siglen
,
337 char *data
, int datalen
) {
338 return 0; /* FIXME */
341 struct ssh_signkey ssh_rsa
= {