1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
|
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "k5-int.h"
#include "dk.h"
#define K5CLENGTH 5 /* 32 bit net byte order integer + one byte seed */
static krb5_error_code
krb5_dk_decrypt_maybe_trunc_hmac(const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
const krb5_keyblock *key,
krb5_keyusage usage,
const krb5_data *ivec,
const krb5_data *input,
krb5_data *output,
size_t hmacsize,
int ivec_mode);
krb5_error_code
krb5_dk_decrypt(const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
const krb5_keyblock *key, krb5_keyusage usage,
const krb5_data *ivec, const krb5_data *input,
krb5_data *output)
{
return krb5_dk_decrypt_maybe_trunc_hmac(enc, hash, key, usage,
ivec, input, output, 0, 0);
}
krb5_error_code
krb5int_aes_dk_decrypt(const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
const krb5_keyblock *key, krb5_keyusage usage,
const krb5_data *ivec, const krb5_data *input,
krb5_data *output)
{
return krb5_dk_decrypt_maybe_trunc_hmac(enc, hash, key, usage,
ivec, input, output, 96 / 8, 1);
}
static krb5_error_code
krb5_dk_decrypt_maybe_trunc_hmac(const struct krb5_enc_provider *enc,
const struct krb5_hash_provider *hash,
const krb5_keyblock *key, krb5_keyusage usage,
const krb5_data *ivec, const krb5_data *input,
krb5_data *output, size_t hmacsize,
int ivec_mode)
{
krb5_error_code ret;
size_t hashsize, blocksize, keybytes, keylength, enclen, plainlen;
unsigned char *plaindata, *kedata, *kidata, *cksum, *cn;
krb5_keyblock ke, ki;
krb5_data d1, d2;
unsigned char constantdata[K5CLENGTH];
/* allocate and set up ciphertext and to-be-derived keys */
hashsize = hash->hashsize;
blocksize = enc->block_size;
keybytes = enc->keybytes;
keylength = enc->keylength;
if (hmacsize == 0)
hmacsize = hashsize;
else if (hmacsize > hashsize)
return KRB5KRB_AP_ERR_BAD_INTEGRITY;
enclen = input->length - hmacsize;
if ((kedata = (unsigned char *) malloc(keylength)) == NULL)
return(ENOMEM);
if ((kidata = (unsigned char *) malloc(keylength)) == NULL) {
free(kedata);
return(ENOMEM);
}
if ((plaindata = (unsigned char *) malloc(enclen)) == NULL) {
free(kidata);
free(kedata);
return(ENOMEM);
}
if ((cksum = (unsigned char *) malloc(hashsize)) == NULL) {
free(plaindata);
free(kidata);
free(kedata);
return(ENOMEM);
}
ke.contents = kedata;
ke.length = keylength;
ki.contents = kidata;
ki.length = keylength;
/* derive the keys */
d1.data = (char *) constantdata;
d1.length = K5CLENGTH;
d1.data[0] = (usage>>24)&0xff;
d1.data[1] = (usage>>16)&0xff;
d1.data[2] = (usage>>8)&0xff;
d1.data[3] = usage&0xff;
d1.data[4] = (char) 0xAA;
if ((ret = krb5_derive_key(enc, key, &ke, &d1)) != 0)
goto cleanup;
d1.data[4] = 0x55;
if ((ret = krb5_derive_key(enc, key, &ki, &d1)) != 0)
goto cleanup;
/* decrypt the ciphertext */
d1.length = enclen;
d1.data = input->data;
d2.length = enclen;
d2.data = (char *) plaindata;
if ((ret = ((*(enc->decrypt))(&ke, ivec, &d1, &d2))) != 0)
goto cleanup;
if (ivec != NULL && ivec->length == blocksize) {
if (ivec_mode == 0)
cn = (unsigned char *) d1.data + d1.length - blocksize;
else if (ivec_mode == 1) {
int nblocks = (d1.length + blocksize - 1) / blocksize;
cn = d1.data + blocksize * (nblocks - 2);
} else
abort();
} else
cn = NULL;
/* verify the hash */
d1.length = hashsize;
d1.data = (char *) cksum;
if ((ret = krb5_hmac(hash, &ki, 1, &d2, &d1)) != 0)
goto cleanup;
if (memcmp(cksum, input->data+enclen, hmacsize) != 0) {
ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
goto cleanup;
}
/* because this encoding isn't self-describing wrt length, the
best we can do here is to compute the length minus the
confounder. */
plainlen = enclen - blocksize;
if (output->length < plainlen)
return(KRB5_BAD_MSIZE);
output->length = plainlen;
memcpy(output->data, d2.data+blocksize, output->length);
if (cn != NULL)
memcpy(ivec->data, cn, blocksize);
ret = 0;
cleanup:
memset(kedata, 0, keylength);
memset(kidata, 0, keylength);
memset(plaindata, 0, enclen);
memset(cksum, 0, hashsize);
free(cksum);
free(plaindata);
free(kidata);
free(kedata);
return(ret);
}
#ifdef ATHENA_DES3_KLUDGE
krb5_error_code
krb5_marc_dk_decrypt(enc, hash, key, usage, ivec, input, output)
const struct krb5_enc_provider *enc;
const struct krb5_hash_provider *hash;
const krb5_keyblock *key;
krb5_keyusage usage;
const krb5_data *ivec;
const krb5_data *input;
krb5_data *output;
{
krb5_error_code ret;
size_t hashsize, blocksize, keybytes, keylength, enclen, plainlen;
unsigned char *plaindata, *kedata, *kidata, *cksum, *cn;
krb5_keyblock ke, ki;
krb5_data d1, d2;
unsigned char constantdata[K5CLENGTH];
/* allocate and set up ciphertext and to-be-derived keys */
hashsize = hash->hashsize;
blocksize = enc->block_size;
keybytes = enc->keybytes;
keylength = enc->keylength;
enclen = input->length - hashsize;
if ((kedata = (unsigned char *) malloc(keylength)) == NULL)
return(ENOMEM);
if ((kidata = (unsigned char *) malloc(keylength)) == NULL) {
free(kedata);
return(ENOMEM);
}
if ((plaindata = (unsigned char *) malloc(enclen)) == NULL) {
free(kidata);
free(kedata);
return(ENOMEM);
}
if ((cksum = (unsigned char *) malloc(hashsize)) == NULL) {
free(plaindata);
free(kidata);
free(kedata);
return(ENOMEM);
}
ke.contents = kedata;
ke.length = keylength;
ki.contents = kidata;
ki.length = keylength;
/* derive the keys */
d1.data = constantdata;
d1.length = K5CLENGTH;
d1.data[0] = (usage>>24)&0xff;
d1.data[1] = (usage>>16)&0xff;
d1.data[2] = (usage>>8)&0xff;
d1.data[3] = usage&0xff;
d1.data[4] = 0xAA;
if ((ret = krb5_derive_key(enc, key, &ke, &d1)) != 0)
goto cleanup;
d1.data[4] = 0x55;
if ((ret = krb5_derive_key(enc, key, &ki, &d1)) != 0)
goto cleanup;
/* decrypt the ciphertext */
d1.length = enclen;
d1.data = input->data;
d2.length = enclen;
d2.data = plaindata;
if ((ret = ((*(enc->decrypt))(&ke, ivec, &d1, &d2))) != 0)
goto cleanup;
if (ivec != NULL && ivec->length == blocksize)
cn = d1.data + d1.length - blocksize;
else
cn = NULL;
/* verify the hash */
d1.length = hashsize;
d1.data = cksum;
if ((ret = krb5_hmac(hash, &ki, 1, &d2, &d1)) != 0)
goto cleanup;
if (memcmp(cksum, input->data+enclen, hashsize) != 0) {
ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
goto cleanup;
}
/* because this encoding isn't self-describing wrt length, the
best we can do here is to compute the length minus the
confounder. */
/* get the real plaintext length and copy the data into the output */
plainlen = ((((plaindata+blocksize)[0])<<24) |
(((plaindata+blocksize)[1])<<16) |
(((plaindata+blocksize)[2])<<8) |
((plaindata+blocksize)[3]));
if (plainlen > (enclen - blocksize - 4))
return(KRB5_BAD_MSIZE);
if (output->length < plainlen)
return(KRB5_BAD_MSIZE);
output->length = plainlen;
memcpy(output->data, d2.data+4+blocksize, output->length);
if (cn != NULL)
memcpy(ivec->data, cn, blocksize);
ret = 0;
cleanup:
memset(kedata, 0, keylength);
memset(kidata, 0, keylength);
memset(plaindata, 0, enclen);
memset(cksum, 0, hashsize);
free(cksum);
free(plaindata);
free(kidata);
free(kedata);
return(ret);
}
#endif /* ATHENA_DES3_KLUDGE */
|
