2 * RSA implementation just sufficient for ssh client-side
5 * Rewritten for more speed by Joris van Rantwijk, Jun 1999.
16 int makekey(unsigned char *data
, struct RSAKey
*result
,
17 unsigned char **keystr
, int order
) {
18 unsigned char *p
= data
;
24 result
->bits
= (result
->bits
<< 8) + *p
++;
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).
35 p
+= ssh1_read_bignum(p
, result ?
&result
->exponent
: NULL
);
37 result
->bytes
= (((p
[0] << 8) + p
[1]) + 7) / 8;
38 if (keystr
) *keystr
= p
+2;
39 p
+= ssh1_read_bignum(p
, result ?
&result
->modulus
: NULL
);
41 p
+= ssh1_read_bignum(p
, result ?
&result
->exponent
: NULL
);
46 int makeprivate(unsigned char *data
, struct RSAKey
*result
) {
47 return ssh1_read_bignum(data
, &result
->private_exponent
);
50 void rsaencrypt(unsigned char *data
, int length
, struct RSAKey
*key
) {
55 memmove(data
+key
->bytes
-length
, data
, length
);
59 for (i
= 2; i
< key
->bytes
-length
-1; i
++) {
61 data
[i
] = random_byte();
62 } while (data
[i
] == 0);
64 data
[key
->bytes
-length
-1] = 0;
66 b1
= bignum_from_bytes(data
, key
->bytes
);
68 b2
= modpow(b1
, key
->exponent
, key
->modulus
);
71 for (i
=key
->bytes
; i
-- ;) {
72 *p
++ = bignum_byte(b2
, i
);
79 Bignum
rsadecrypt(Bignum input
, struct RSAKey
*key
) {
81 ret
= modpow(input
, key
->private_exponent
, key
->modulus
);
85 int rsastr_len(struct RSAKey
*key
) {
91 mdlen
= (ssh1_bignum_bitcount(md
)+15) / 16;
92 exlen
= (ssh1_bignum_bitcount(ex
)+15) / 16;
93 return 4 * (mdlen
+exlen
) + 20;
96 void rsastr_fmt(char *str
, struct RSAKey
*key
) {
98 int len
= 0, i
, nibbles
;
99 static const char hex
[] = "0123456789abcdef";
104 len
+= sprintf(str
+len
, "0x");
106 nibbles
= (3 + ssh1_bignum_bitcount(ex
))/4; if (nibbles
<1) nibbles
=1;
107 for (i
=nibbles
; i
-- ;)
108 str
[len
++] = hex
[(bignum_byte(ex
, i
/2) >> (4*(i
%2))) & 0xF];
110 len
+= sprintf(str
+len
, ",0x");
112 nibbles
= (3 + ssh1_bignum_bitcount(md
))/4; if (nibbles
<1) nibbles
=1;
113 for (i
=nibbles
; i
-- ;)
114 str
[len
++] = hex
[(bignum_byte(md
, i
/2) >> (4*(i
%2))) & 0xF];
120 * Generate a fingerprint string for the key. Compatible with the
121 * OpenSSH fingerprint code.
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];
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);
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);
140 MD5Final(digest
, &md5c
);
142 sprintf(buffer
, "%d ", ssh1_bignum_bitcount(key
->modulus
));
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';
147 if (key
->comment
&& slen
< len
-1) {
149 strncpy(str
+slen
+1, key
->comment
, len
-slen
-1);
154 void freersakey(struct RSAKey
*key
) {
155 if (key
->modulus
) freebn(key
->modulus
);
156 if (key
->exponent
) freebn(key
->exponent
);
157 if (key
->private_exponent
) freebn(key
->private_exponent
);
158 if (key
->comment
) sfree(key
->comment
);
161 /* ----------------------------------------------------------------------
162 * Implementation of the ssh-rsa signing key type.
165 #define GET_32BIT(cp) \
166 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
167 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
168 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
169 ((unsigned long)(unsigned char)(cp)[3]))
171 #define PUT_32BIT(cp, value) { \
172 (cp)[0] = (unsigned char)((value) >> 24); \
173 (cp)[1] = (unsigned char)((value) >> 16); \
174 (cp)[2] = (unsigned char)((value) >> 8); \
175 (cp)[3] = (unsigned char)(value); }
177 static void getstring(char **data
, int *datalen
, char **p
, int *length
) {
181 *length
= GET_32BIT(*data
);
182 *datalen
-= 4; *data
+= 4;
183 if (*datalen
< *length
)
186 *data
+= *length
; *datalen
-= *length
;
188 static Bignum
getmp(char **data
, int *datalen
) {
193 getstring(data
, datalen
, &p
, &length
);
196 b
= bignum_from_bytes(p
, length
);
200 static void *rsa2_newkey(char *data
, int len
) {
205 rsa
= smalloc(sizeof(struct RSAKey
));
206 if (!rsa
) return NULL
;
207 getstring(&data
, &len
, &p
, &slen
);
209 if (!p
|| slen
!= 7 || memcmp(p
, "ssh-rsa", 7)) {
213 rsa
->exponent
= getmp(&data
, &len
);
214 rsa
->modulus
= getmp(&data
, &len
);
215 rsa
->private_exponent
= NULL
;
221 static void rsa2_freekey(void *key
) {
222 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
227 static char *rsa2_fmtkey(void *key
) {
228 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
232 len
= rsastr_len(rsa
);
238 static unsigned char *rsa2_public_blob(void *key
, int *len
) {
239 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
240 int elen
, mlen
, bloblen
;
242 unsigned char *blob
, *p
;
244 elen
= (ssh1_bignum_bitcount(rsa
->exponent
)+8)/8;
245 mlen
= (ssh1_bignum_bitcount(rsa
->modulus
)+8)/8;
248 * string "ssh-rsa", mpint exp, mpint mod. Total 19+elen+mlen.
249 * (three length fields, 12+7=19).
251 bloblen
= 19+elen
+mlen
;
252 blob
= smalloc(bloblen
);
254 PUT_32BIT(p
, 7); p
+= 4;
255 memcpy(p
, "ssh-rsa", 7); p
+= 7;
256 PUT_32BIT(p
, elen
); p
+= 4;
257 for (i
= elen
; i
-- ;) *p
++ = bignum_byte(rsa
->exponent
, i
);
258 PUT_32BIT(p
, mlen
); p
+= 4;
259 for (i
= mlen
; i
-- ;) *p
++ = bignum_byte(rsa
->modulus
, i
);
260 assert(p
== blob
+ bloblen
);
265 static unsigned char *rsa2_private_blob(void *key
, int *len
) {
266 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
267 int dlen
, plen
, qlen
, ulen
, bloblen
;
269 unsigned char *blob
, *p
;
271 dlen
= (ssh1_bignum_bitcount(rsa
->private_exponent
)+8)/8;
272 plen
= (ssh1_bignum_bitcount(rsa
->p
)+8)/8;
273 qlen
= (ssh1_bignum_bitcount(rsa
->q
)+8)/8;
274 ulen
= (ssh1_bignum_bitcount(rsa
->iqmp
)+8)/8;
277 * mpint private_exp, mpint p, mpint q, mpint iqmp. Total 16 +
280 bloblen
= 16+dlen
+plen
+qlen
+ulen
;
281 blob
= smalloc(bloblen
);
283 PUT_32BIT(p
, dlen
); p
+= 4;
284 for (i
= dlen
; i
-- ;) *p
++ = bignum_byte(rsa
->private_exponent
, i
);
285 PUT_32BIT(p
, plen
); p
+= 4;
286 for (i
= plen
; i
-- ;) *p
++ = bignum_byte(rsa
->p
, i
);
287 PUT_32BIT(p
, qlen
); p
+= 4;
288 for (i
= qlen
; i
-- ;) *p
++ = bignum_byte(rsa
->q
, i
);
289 PUT_32BIT(p
, ulen
); p
+= 4;
290 for (i
= ulen
; i
-- ;) *p
++ = bignum_byte(rsa
->iqmp
, i
);
291 assert(p
== blob
+ bloblen
);
296 static void *rsa2_createkey(unsigned char *pub_blob
, int pub_len
,
297 unsigned char *priv_blob
, int priv_len
) {
299 char *pb
= (char *)priv_blob
;
301 rsa
= rsa2_newkey((char *)pub_blob
, pub_len
);
302 rsa
->private_exponent
= getmp(&pb
, &priv_len
);
303 rsa
->p
= getmp(&pb
, &priv_len
);
304 rsa
->q
= getmp(&pb
, &priv_len
);
305 rsa
->iqmp
= getmp(&pb
, &priv_len
);
310 static void *rsa2_openssh_createkey(unsigned char **blob
, int *len
) {
311 char **b
= (char **)blob
;
314 rsa
= smalloc(sizeof(struct RSAKey
));
315 if (!rsa
) return NULL
;
318 rsa
->modulus
= getmp(b
, len
);
319 rsa
->exponent
= getmp(b
, len
);
320 rsa
->private_exponent
= getmp(b
, len
);
321 rsa
->iqmp
= getmp(b
, len
);
322 rsa
->p
= getmp(b
, len
);
323 rsa
->q
= getmp(b
, len
);
325 if (!rsa
->modulus
|| !rsa
->exponent
|| !rsa
->private_exponent
||
326 !rsa
->iqmp
|| !rsa
->p
|| !rsa
->q
) {
328 sfree(rsa
->exponent
);
329 sfree(rsa
->private_exponent
);
340 static char *rsa2_fingerprint(void *key
) {
341 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
342 struct MD5Context md5c
;
343 unsigned char digest
[16], lenbuf
[4];
344 char buffer
[16*3+40];
349 MD5Update(&md5c
, "\0\0\0\7ssh-rsa", 11);
351 #define ADD_BIGNUM(bignum) \
352 numlen = (ssh1_bignum_bitcount(bignum)+8)/8; \
353 PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \
354 for (i = numlen; i-- ;) { \
355 unsigned char c = bignum_byte(bignum, i); \
356 MD5Update(&md5c, &c, 1); \
358 ADD_BIGNUM(rsa
->exponent
);
359 ADD_BIGNUM(rsa
->modulus
);
362 MD5Final(digest
, &md5c
);
364 sprintf(buffer
, "ssh-rsa %d ", ssh1_bignum_bitcount(rsa
->modulus
));
365 for (i
= 0; i
< 16; i
++)
366 sprintf(buffer
+strlen(buffer
), "%s%02x", i?
":":"", digest
[i
]);
367 ret
= smalloc(strlen(buffer
)+1);
374 * This is the magic ASN.1/DER prefix that goes in the decoded
375 * signature, between the string of FFs and the actual SHA hash
376 * value. The meaning of it is:
378 * 00 -- this marks the end of the FFs; not part of the ASN.1 bit itself
380 * 30 21 -- a constructed SEQUENCE of length 0x21
381 * 30 09 -- a constructed sub-SEQUENCE of length 9
382 * 06 05 -- an object identifier, length 5
383 * 2B 0E 03 02 1A -- object id { 1 3 14 3 2 26 }
384 * (the 1,3 comes from 0x2B = 43 = 40*1+3)
386 * 04 14 -- a primitive OCTET STRING of length 0x14
387 * [0x14 bytes of hash data follows]
389 * The object id in the middle there is listed as `id-sha1' in
390 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1d2.asn (the
391 * ASN module for PKCS #1) and its expanded form is as follows:
393 * id-sha1 OBJECT IDENTIFIER ::= {
394 * iso(1) identified-organization(3) oiw(14) secsig(3)
397 static unsigned char asn1_weird_stuff
[] = {
398 0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2B,
399 0x0E,0x03,0x02,0x1A,0x05,0x00,0x04,0x14,
402 #define ASN1_LEN ( (int) sizeof(asn1_weird_stuff) )
404 static int rsa2_verifysig(void *key
, char *sig
, int siglen
,
405 char *data
, int datalen
) {
406 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
410 int bytes
, i
, j
, ret
;
411 unsigned char hash
[20];
413 getstring(&sig
, &siglen
, &p
, &slen
);
414 if (!p
|| slen
!= 7 || memcmp(p
, "ssh-rsa", 7)) {
417 in
= getmp(&sig
, &siglen
);
418 out
= modpow(in
, rsa
->exponent
, rsa
->modulus
);
423 bytes
= ssh1_bignum_bitcount(rsa
->modulus
) / 8;
424 /* Top (partial) byte should be zero. */
425 if (bignum_byte(out
, bytes
-1) != 0)
427 /* First whole byte should be 1. */
428 if (bignum_byte(out
, bytes
-2) != 1)
430 /* Most of the rest should be FF. */
431 for (i
= bytes
-3; i
>= 20 + ASN1_LEN
; i
--) {
432 if (bignum_byte(out
, i
) != 0xFF)
435 /* Then we expect to see the asn1_weird_stuff. */
436 for (i
= 20 + ASN1_LEN
- 1, j
=0; i
>= 20; i
--,j
++) {
437 if (bignum_byte(out
, i
) != asn1_weird_stuff
[j
])
440 /* Finally, we expect to see the SHA-1 hash of the signed data. */
441 SHA_Simple(data
, datalen
, hash
);
442 for (i
= 19, j
=0; i
>= 0; i
--,j
++) {
443 if (bignum_byte(out
, i
) != hash
[j
])
450 unsigned char *rsa2_sign(void *key
, char *data
, int datalen
, int *siglen
) {
451 struct RSAKey
*rsa
= (struct RSAKey
*)key
;
452 unsigned char *bytes
;
454 unsigned char hash
[20];
458 SHA_Simple(data
, datalen
, hash
);
460 nbytes
= (ssh1_bignum_bitcount(rsa
->modulus
)-1) / 8;
461 bytes
= smalloc(nbytes
);
464 for (i
= 1; i
< nbytes
-20-ASN1_LEN
; i
++)
466 for (i
= nbytes
-20-ASN1_LEN
, j
=0; i
< nbytes
-20; i
++,j
++)
467 bytes
[i
] = asn1_weird_stuff
[j
];
468 for (i
= nbytes
-20, j
=0; i
< nbytes
; i
++,j
++)
471 in
= bignum_from_bytes(bytes
, nbytes
);
474 out
= modpow(in
, rsa
->private_exponent
, rsa
->modulus
);
477 nbytes
= (ssh1_bignum_bitcount(out
)+7)/8;
478 bytes
= smalloc(4+7+4+nbytes
);
480 memcpy(bytes
+4, "ssh-rsa", 7);
481 PUT_32BIT(bytes
+4+7, nbytes
);
482 for (i
= 0; i
< nbytes
; i
++)
483 bytes
[4+7+4+i
] = bignum_byte(out
, nbytes
-1-i
);
486 *siglen
= 4+7+4+nbytes
;
490 const struct ssh_signkey ssh_rsa
= {
497 rsa2_openssh_createkey
,