summaryrefslogtreecommitdiff
path: root/security/nss/lib/freebl/aeskeywrap.c
blob: ee909dbd052a83f766c768e76a865fbfc0fff701 (plain)
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
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
/*
 * aeskeywrap.c - implement AES Key Wrap algorithm from RFC 3394
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif

#include "prcpucfg.h"
#if defined(IS_LITTLE_ENDIAN) || defined(SHA_NO_LONG_LONG)
#define BIG_ENDIAN_WITH_64_BIT_REGISTERS 0
#else
#define BIG_ENDIAN_WITH_64_BIT_REGISTERS 1
#endif
#include "prtypes.h" /* for PRUintXX */
#include "secport.h" /* for PORT_XXX */
#include "secerr.h"
#include "blapi.h" /* for AES_ functions */
#include "rijndael.h"

struct AESKeyWrapContextStr {
    AESContext aescx;
    unsigned char iv[AES_KEY_WRAP_IV_BYTES];
    void *mem; /* Pointer to beginning of allocated memory. */
};

/******************************************/
/*
** AES key wrap algorithm, RFC 3394
*/

AESKeyWrapContext *
AESKeyWrap_AllocateContext(void)
{
    /* aligned_alloc is C11 so we have to do it the old way. */
    AESKeyWrapContext *ctx = PORT_ZAlloc(sizeof(AESKeyWrapContext) + 15);
    if (ctx == NULL) {
        PORT_SetError(SEC_ERROR_NO_MEMORY);
        return NULL;
    }
    ctx->mem = ctx;
    return (AESKeyWrapContext *)(((uintptr_t)ctx + 15) & ~(uintptr_t)0x0F);
}

SECStatus
AESKeyWrap_InitContext(AESKeyWrapContext *cx,
                       const unsigned char *key,
                       unsigned int keylen,
                       const unsigned char *iv,
                       int x1,
                       unsigned int encrypt,
                       unsigned int x2)
{
    SECStatus rv = SECFailure;
    if (!cx) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return SECFailure;
    }
    if (iv) {
        memcpy(cx->iv, iv, sizeof cx->iv);
    } else {
        memset(cx->iv, 0xA6, sizeof cx->iv);
    }
    rv = AES_InitContext(&cx->aescx, key, keylen, NULL, NSS_AES, encrypt,
                         AES_BLOCK_SIZE);
    return rv;
}

/*
** Create a new AES context suitable for AES encryption/decryption.
**  "key" raw key data
**  "keylen" the number of bytes of key data (16, 24, or 32)
*/
extern AESKeyWrapContext *
AESKeyWrap_CreateContext(const unsigned char *key, const unsigned char *iv,
                         int encrypt, unsigned int keylen)
{
    SECStatus rv;
    AESKeyWrapContext *cx = AESKeyWrap_AllocateContext();
    if (!cx)
        return NULL; /* error is already set */
    rv = AESKeyWrap_InitContext(cx, key, keylen, iv, 0, encrypt, 0);
    if (rv != SECSuccess) {
        PORT_Free(cx->mem);
        cx = NULL; /* error should already be set */
    }
    return cx;
}

/*
** Destroy a AES KeyWrap context.
**  "cx" the context
**  "freeit" if PR_TRUE then free the object as well as its sub-objects
*/
extern void
AESKeyWrap_DestroyContext(AESKeyWrapContext *cx, PRBool freeit)
{
    if (cx) {
        AES_DestroyContext(&cx->aescx, PR_FALSE);
        /*  memset(cx, 0, sizeof *cx); */
        if (freeit) {
            PORT_Free(cx->mem);
        }
    }
}

#if !BIG_ENDIAN_WITH_64_BIT_REGISTERS

/* The AES Key Wrap algorithm has 64-bit values that are ALWAYS big-endian
** (Most significant byte first) in memory.  The only ALU operations done
** on them are increment, decrement, and XOR.  So, on little-endian CPUs,
** and on CPUs that lack 64-bit registers, these big-endian 64-bit operations
** are simulated in the following code.  This is thought to be faster and
** simpler than trying to convert the data to little-endian and back.
*/

/* A and T point to two 64-bit values stored most signficant byte first
** (big endian).  This function increments the 64-bit value T, and then
** XORs it with A, changing A.
*/
static void
increment_and_xor(unsigned char *A, unsigned char *T)
{
    if (!++T[7])
        if (!++T[6])
            if (!++T[5])
                if (!++T[4])
                    if (!++T[3])
                        if (!++T[2])
                            if (!++T[1])
                                ++T[0];

    A[0] ^= T[0];
    A[1] ^= T[1];
    A[2] ^= T[2];
    A[3] ^= T[3];
    A[4] ^= T[4];
    A[5] ^= T[5];
    A[6] ^= T[6];
    A[7] ^= T[7];
}

/* A and T point to two 64-bit values stored most signficant byte first
** (big endian).  This function XORs T with A, giving a new A, then
** decrements the 64-bit value T.
*/
static void
xor_and_decrement(PRUint64 *A, PRUint64 *T)
{
    unsigned char *TP = (unsigned char *)T;
    const PRUint64 mask = 0xFF;
    *A = ((*A & mask << 56) ^ (*T & mask << 56)) |
         ((*A & mask << 48) ^ (*T & mask << 48)) |
         ((*A & mask << 40) ^ (*T & mask << 40)) |
         ((*A & mask << 32) ^ (*T & mask << 32)) |
         ((*A & mask << 24) ^ (*T & mask << 23)) |
         ((*A & mask << 16) ^ (*T & mask << 16)) |
         ((*A & mask << 8) ^ (*T & mask << 8)) |
         ((*A & mask) ^ (*T & mask));

    if (!TP[7]--)
        if (!TP[6]--)
            if (!TP[5]--)
                if (!TP[4]--)
                    if (!TP[3]--)
                        if (!TP[2]--)
                            if (!TP[1]--)
                                TP[0]--;
}

/* Given an unsigned long t (in host byte order), store this value as a
** 64-bit big-endian value (MSB first) in *pt.
*/
static void
set_t(unsigned char *pt, unsigned long t)
{
    pt[7] = (unsigned char)t;
    t >>= 8;
    pt[6] = (unsigned char)t;
    t >>= 8;
    pt[5] = (unsigned char)t;
    t >>= 8;
    pt[4] = (unsigned char)t;
    t >>= 8;
    pt[3] = (unsigned char)t;
    t >>= 8;
    pt[2] = (unsigned char)t;
    t >>= 8;
    pt[1] = (unsigned char)t;
    t >>= 8;
    pt[0] = (unsigned char)t;
}

#endif

/*
** Perform AES key wrap.
**  "cx" the context
**  "output" the output buffer to store the encrypted data.
**  "outputLen" how much data is stored in "output". Set by the routine
**     after some data is stored in output.
**  "maxOutputLen" the maximum amount of data that can ever be
**     stored in "output"
**  "input" the input data
**  "inputLen" the amount of input data
*/
extern SECStatus
AESKeyWrap_Encrypt(AESKeyWrapContext *cx, unsigned char *output,
                   unsigned int *pOutputLen, unsigned int maxOutputLen,
                   const unsigned char *input, unsigned int inputLen)
{
    PRUint64 *R = NULL;
    unsigned int nBlocks;
    unsigned int i, j;
    unsigned int aesLen = AES_BLOCK_SIZE;
    unsigned int outLen = inputLen + AES_KEY_WRAP_BLOCK_SIZE;
    SECStatus s = SECFailure;
    /* These PRUint64s are ALWAYS big endian, regardless of CPU orientation. */
    PRUint64 t;
    PRUint64 B[2];

#define A B[0]

    /* Check args */
    if (!inputLen || 0 != inputLen % AES_KEY_WRAP_BLOCK_SIZE) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        return s;
    }
#ifdef maybe
    if (!output && pOutputLen) { /* caller is asking for output size */
        *pOutputLen = outLen;
        return SECSuccess;
    }
#endif
    if (maxOutputLen < outLen) {
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        return s;
    }
    if (cx == NULL || output == NULL || input == NULL) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return s;
    }
    nBlocks = inputLen / AES_KEY_WRAP_BLOCK_SIZE;
    R = PORT_NewArray(PRUint64, nBlocks + 1);
    if (!R)
        return s; /* error is already set. */
    /*
    ** 1) Initialize variables.
    */
    memcpy(&A, cx->iv, AES_KEY_WRAP_IV_BYTES);
    memcpy(&R[1], input, inputLen);
#if BIG_ENDIAN_WITH_64_BIT_REGISTERS
    t = 0;
#else
    memset(&t, 0, sizeof t);
#endif
    /*
    ** 2) Calculate intermediate values.
    */
    for (j = 0; j < 6; ++j) {
        for (i = 1; i <= nBlocks; ++i) {
            B[1] = R[i];
            s = AES_Encrypt(&cx->aescx, (unsigned char *)B, &aesLen,
                            sizeof B, (unsigned char *)B, sizeof B);
            if (s != SECSuccess)
                break;
            R[i] = B[1];
/* here, increment t and XOR A with t (in big endian order); */
#if BIG_ENDIAN_WITH_64_BIT_REGISTERS
            A ^= ++t;
#else
            increment_and_xor((unsigned char *)&A, (unsigned char *)&t);
#endif
        }
    }
    /*
    ** 3) Output the results.
    */
    if (s == SECSuccess) {
        R[0] = A;
        memcpy(output, &R[0], outLen);
        if (pOutputLen)
            *pOutputLen = outLen;
    } else if (pOutputLen) {
        *pOutputLen = 0;
    }
    PORT_ZFree(R, outLen);
    return s;
}
#undef A

/*
** Perform AES key unwrap.
**  "cx" the context
**  "output" the output buffer to store the decrypted data.
**  "outputLen" how much data is stored in "output". Set by the routine
**     after some data is stored in output.
**  "maxOutputLen" the maximum amount of data that can ever be
**     stored in "output"
**  "input" the input data
**  "inputLen" the amount of input data
*/
extern SECStatus
AESKeyWrap_Decrypt(AESKeyWrapContext *cx, unsigned char *output,
                   unsigned int *pOutputLen, unsigned int maxOutputLen,
                   const unsigned char *input, unsigned int inputLen)
{
    PRUint64 *R = NULL;
    unsigned int nBlocks;
    unsigned int i, j;
    unsigned int aesLen = AES_BLOCK_SIZE;
    unsigned int outLen;
    SECStatus s = SECFailure;
    /* These PRUint64s are ALWAYS big endian, regardless of CPU orientation. */
    PRUint64 t;
    PRUint64 B[2];

    /* Check args */
    if (inputLen < 3 * AES_KEY_WRAP_BLOCK_SIZE ||
        0 != inputLen % AES_KEY_WRAP_BLOCK_SIZE) {
        PORT_SetError(SEC_ERROR_INPUT_LEN);
        return s;
    }
    outLen = inputLen - AES_KEY_WRAP_BLOCK_SIZE;
#ifdef maybe
    if (!output && pOutputLen) { /* caller is asking for output size */
        *pOutputLen = outLen;
        return SECSuccess;
    }
#endif
    if (maxOutputLen < outLen) {
        PORT_SetError(SEC_ERROR_OUTPUT_LEN);
        return s;
    }
    if (cx == NULL || output == NULL || input == NULL) {
        PORT_SetError(SEC_ERROR_INVALID_ARGS);
        return s;
    }
    nBlocks = inputLen / AES_KEY_WRAP_BLOCK_SIZE;
    R = PORT_NewArray(PRUint64, nBlocks);
    if (!R)
        return s; /* error is already set. */
    nBlocks--;
    /*
    ** 1) Initialize variables.
    */
    memcpy(&R[0], input, inputLen);
    B[0] = R[0];
#if BIG_ENDIAN_WITH_64_BIT_REGISTERS
    t = 6UL * nBlocks;
#else
    set_t((unsigned char *)&t, 6UL * nBlocks);
#endif
    /*
    ** 2) Calculate intermediate values.
    */
    for (j = 0; j < 6; ++j) {
        for (i = nBlocks; i; --i) {
/* here, XOR A with t (in big endian order) and decrement t; */
#if BIG_ENDIAN_WITH_64_BIT_REGISTERS
            B[0] ^= t--;
#else
            xor_and_decrement(&B[0], &t);
#endif
            B[1] = R[i];
            s = AES_Decrypt(&cx->aescx, (unsigned char *)B, &aesLen,
                            sizeof B, (unsigned char *)B, sizeof B);
            if (s != SECSuccess)
                break;
            R[i] = B[1];
        }
    }
    /*
    ** 3) Output the results.
    */
    if (s == SECSuccess) {
        int bad = memcmp(&B[0], cx->iv, AES_KEY_WRAP_IV_BYTES);
        if (!bad) {
            memcpy(output, &R[1], outLen);
            if (pOutputLen)
                *pOutputLen = outLen;
        } else {
            s = SECFailure;
            PORT_SetError(SEC_ERROR_BAD_DATA);
            if (pOutputLen)
                *pOutputLen = 0;
        }
    } else if (pOutputLen) {
        *pOutputLen = 0;
    }
    PORT_ZFree(R, inputLen);
    return s;
}
#undef A