1 /* Transform module - bulk data transformation */
3 /* For now it's hard-coded to do sequence
4 number/pkcs5/serpent-cbcmac/serpent with a 256 bit key for each
5 instance of serpent. We also require key material for the IVs for
6 cbcmac and cbc. Hack: we're not using full 128-bit IVs, we're just
7 using 32 bits and encrypting to get the full IV to save space in
8 the packets sent over the wire. */
15 /* Required key length in bytes */
16 #define REQUIRED_KEYLEN ((512+64+32)/8)
21 struct transform_if ops
;
22 uint32_t max_seq_skew
;
25 struct transform_inst
{
26 struct transform_inst_if ops
;
27 struct keyInstance cryptkey
;
28 struct keyInstance mackey
;
39 static bool_t
transform_setkey(void *sst
, uint8_t *key
, uint32_t keylen
)
41 struct transform_inst
*ti
=sst
;
43 if (keylen
<REQUIRED_KEYLEN
) {
44 Message(M_ERROR
,"transform_create: insufficient key material supplied "
45 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN
,keylen
);
52 printf("Setting key to: ");
53 for (i
=0; i
<keylen
; i
++)
54 printf("%02x",key
[i
]);
59 serpent_makekey(&ti
->cryptkey
,256,key
);
60 serpent_makekey(&ti
->mackey
,256,key
+32);
61 ti
->cryptiv
=*(uint32_t *)(key
+64);
62 ti
->maciv
=*(uint32_t *)(key
+68);
63 ti
->sendseq
=*(uint32_t *)(key
+72);
64 ti
->lastrecvseq
=ti
->sendseq
;
70 static void transform_delkey(void *sst
)
72 struct transform_inst
*ti
=sst
;
74 memset(&ti
->cryptkey
,0,sizeof(ti
->cryptkey
));
75 memset(&ti
->mackey
,0,sizeof(ti
->mackey
));
79 static uint32_t transform_forward(void *sst
, struct buffer_if
*buf
,
82 struct transform_inst
*ti
=sst
;
91 *errmsg
="transform unkeyed";
96 *(uint32_t *)buf_prepend(buf
,4)=htonl(ti
->sendseq
);
99 /* PKCS5, stolen from IWJ */
100 /* eg with blocksize=4 mask=3 mask+2=5 */
101 /* msgsize 20 21 22 23 24 */
102 padlen
= PKCS5_MASK
-buf
->size
; /* -17 -18 -19 -16 -17 */
103 padlen
&= PKCS5_MASK
; /* 3 2 1 0 3 */
104 padlen
++; /* 4 3 2 1 4 */
106 padp
=buf_append(buf
,padlen
);
107 memset(padp
,padlen
,padlen
);
109 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
110 one encryption. Then we do the MAC and append the result. We don't
111 bother sending the IV - it's the same each time. (If we wanted to send
112 it we've have to add 16 bytes to each message, not 4, so that the
113 message stays a multiple of 16 bytes long.) */
116 serpent_encrypt(&ti
->mackey
,iv
,macacc
);
118 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
119 block encrypted once again. */
120 for (n
=(uint32_t *)buf
->start
; n
<(uint32_t *)(buf
->start
+buf
->size
); n
+=4)
122 macplain
[0]=macacc
[0]^n
[0];
123 macplain
[1]=macacc
[1]^n
[1];
124 macplain
[2]=macacc
[2]^n
[2];
125 macplain
[3]=macacc
[3]^n
[3];
126 serpent_encrypt(&ti
->mackey
,macplain
,macacc
);
128 serpent_encrypt(&ti
->mackey
,macacc
,macacc
);
129 memcpy(buf_append(buf
,16),macacc
,16);
131 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
132 and prepend the IV before increasing it. */
135 serpent_encrypt(&ti
->cryptkey
,iv
,iv
);
137 /* CBC: each block is XORed with the previous encrypted block (or the IV)
138 before being encrypted. */
140 for (n
=(uint32_t *)buf
->start
; n
<(uint32_t *)(buf
->start
+buf
->size
); n
+=4)
146 serpent_encrypt(&ti
->cryptkey
,n
,n
);
150 *(uint32_t *)buf_prepend(buf
,4)=ti
->cryptiv
;
156 static uint32_t transform_reverse(void *sst
, struct buffer_if
*buf
,
159 struct transform_inst
*ti
=sst
;
163 uint32_t seqnum
, skew
;
166 uint32_t macplain
[4];
169 uint32_t *macexpected
;
172 *errmsg
="transform unkeyed";
178 iv
[0]=*(uint32_t *)buf_unprepend(buf
,4);
179 serpent_encrypt(&ti
->cryptkey
,iv
,iv
);
180 /* XXX assert bufsize is multiple of blocksize */
181 for (n
=(uint32_t *)buf
->start
; n
<(uint32_t *)(buf
->start
+buf
->size
); n
+=4)
183 pct
[0]=n
[0]; pct
[1]=n
[1]; pct
[2]=n
[2]; pct
[3]=n
[3];
184 serpent_decrypt(&ti
->cryptkey
,n
,n
);
189 iv
[0]=pct
[0]; iv
[1]=pct
[1]; iv
[2]=pct
[2]; iv
[3]=pct
[3];
193 macexpected
=buf_unappend(buf
,16);
196 serpent_encrypt(&ti
->mackey
,iv
,macacc
);
198 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
199 block encrypted once again. */
200 for (n
=(uint32_t *)buf
->start
; n
<(uint32_t *)(buf
->start
+buf
->size
); n
+=4)
202 macplain
[0]=macacc
[0]^n
[0];
203 macplain
[1]=macacc
[1]^n
[1];
204 macplain
[2]=macacc
[2]^n
[2];
205 macplain
[3]=macacc
[3]^n
[3];
206 serpent_encrypt(&ti
->mackey
,macplain
,macacc
);
208 serpent_encrypt(&ti
->mackey
,macacc
,macacc
);
209 if (memcmp(macexpected
,macacc
,16)!=0) {
210 *errmsg
="invalid MAC";
214 /* PKCS5, stolen from IWJ */
216 padp
=buf_unappend(buf
,1);
218 if (!padlen
|| (padlen
> PKCS5_MASK
+1)) {
219 *errmsg
="pkcs5: invalid length";
223 padp
=buf_unappend(buf
,padlen
-1);
224 for (i
=0; i
<padlen
-1; i
++) {
225 if (*++padp
!= padlen
) {
226 *errmsg
="pkcs5: corrupted padding";
231 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
232 is only allowed to increase. */
233 seqnum
=ntohl(*(uint32_t *)buf_unprepend(buf
,4));
234 skew
=seqnum
-ti
->lastrecvseq
;
237 ti
->lastrecvseq
=seqnum
;
238 } else if ((0-skew
)<10) {
242 *errmsg
="seqnum: too much skew";
249 static void transform_destroy(void *sst
)
251 struct transform_inst
*st
=sst
;
253 memset(st
,0,sizeof(*st
)); /* Destroy key material */
257 static struct transform_inst_if
*transform_create(void *sst
)
259 struct transform_inst
*ti
;
260 struct transform
*st
=sst
;
262 ti
=safe_malloc(sizeof(*ti
),"transform_create");
266 ti
->ops
.setkey
=transform_setkey
;
267 ti
->ops
.delkey
=transform_delkey
;
268 ti
->ops
.forwards
=transform_forward
;
269 ti
->ops
.reverse
=transform_reverse
;
270 ti
->ops
.destroy
=transform_destroy
;
271 ti
->max_skew
=st
->max_seq_skew
;
277 static list_t
*transform_apply(closure_t
*self
, struct cloc loc
,
278 dict_t
*context
, list_t
*args
)
280 struct transform
*st
;
284 st
=safe_malloc(sizeof(*st
),"serpent");
285 st
->cl
.description
="serpent-cbc256";
286 st
->cl
.type
=CL_TRANSFORM
;
288 st
->cl
.interface
=&st
->ops
;
290 st
->ops
.max_start_pad
=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
292 st
->ops
.max_end_pad
=16; /* 16byte CBCMAC */
294 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
295 for CBCMAC-IV, and 32 bits for init sequence number */
296 st
->ops
.keylen
=REQUIRED_KEYLEN
;
297 st
->ops
.create
=transform_create
;
299 /* First parameter must be a dict */
300 item
=list_elem(args
,0);
301 if (!item
|| item
->type
!=t_dict
)
302 cfgfatal(loc
,"userv-ipif","parameter must be a dictionary\n");
304 dict
=item
->data
.dict
;
305 st
->max_seq_skew
=dict_read_number(dict
, "max-sequence-skew",
306 False
, "serpent-cbc256", loc
, 10);
308 return new_closure(&st
->cl
);
311 init_module transform_module
;
312 void transform_module(dict_t
*dict
)
314 struct keyInstance k
;
316 uint32_t plaintext
[4];
317 uint32_t ciphertext
[4];
319 /* Serpent self-test */
321 serpent_makekey(&k
,256,data
);
322 plaintext
[0]=0x00000000;
323 plaintext
[1]=0x00000001;
324 plaintext
[2]=0x00000002;
325 plaintext
[3]=0x00000003;
326 serpent_encrypt(&k
,plaintext
,ciphertext
);
327 if (ciphertext
[3]!=0x7ca73bb0 ||
328 ciphertext
[2]!=0x83C31E69 ||
329 ciphertext
[1]!=0xec52bd82 ||
330 ciphertext
[0]!=0x27a46120) {
331 fatal("transform_module: serpent failed self-test (encrypt)\n");
333 serpent_decrypt(&k
,ciphertext
,plaintext
);
334 if (plaintext
[0]!=0 ||
338 fatal("transform_module: serpent failed self-test (decrypt)\n");
341 add_closure(dict
,"serpent256-cbc",transform_apply
);