aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/openssl/crypto/modes/wrap128.c
blob: d7e56cc260adbf5b9eef9d4e867e5b9daf12b502 (plain) (blame)
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
/*
 * Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/**  Beware!
 *
 *  Following wrapping modes were designed for AES but this implementation
 *  allows you to use them for any 128 bit block cipher.
 */

#include "internal/cryptlib.h"
#include <openssl/modes.h>

/** RFC 3394 section 2.2.3.1 Default Initial Value */
static const unsigned char default_iv[] = {
    0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
};

/** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
static const unsigned char default_aiv[] = {
    0xA6, 0x59, 0x59, 0xA6
};

/** Input size limit: lower than maximum of standards but far larger than
 *  anything that will be used in practice.
 */
#define CRYPTO128_WRAP_MAX (1UL << 31)

/** Wrapping according to RFC 3394 section 2.2.1.
 *
 *  @param[in]  key    Key value.
 *  @param[in]  iv     IV value. Length = 8 bytes. NULL = use default_iv.
 *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
 *  @param[in]  inlen  Length of in.
 *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen does not consist of n 64-bit blocks, n >= 2.
 *                     or if inlen > CRYPTO128_WRAP_MAX.
 *                     Output length if wrapping succeeded.
 */
size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
                       unsigned char *out,
                       const unsigned char *in, size_t inlen,
                       block128_f block)
{
    unsigned char *A, B[16], *R;
    size_t i, j, t;
    if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
        return 0;
    A = B;
    t = 1;
    memmove(out + 8, in, inlen);
    if (!iv)
        iv = default_iv;

    memcpy(A, iv, 8);

    for (j = 0; j < 6; j++) {
        R = out + 8;
        for (i = 0; i < inlen; i += 8, t++, R += 8) {
            memcpy(B + 8, R, 8);
            block(B, B, key);
            A[7] ^= (unsigned char)(t & 0xff);
            if (t > 0xff) {
                A[6] ^= (unsigned char)((t >> 8) & 0xff);
                A[5] ^= (unsigned char)((t >> 16) & 0xff);
                A[4] ^= (unsigned char)((t >> 24) & 0xff);
            }
            memcpy(R, B + 8, 8);
        }
    }
    memcpy(out, A, 8);
    return inlen + 8;
}

/** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
 *  The IV check (step 3) is responsibility of the caller.
 *
 *  @param[in]  key    Key value.
 *  @param[out] iv     Unchecked IV value. Minimal buffer length = 8 bytes.
 *  @param[out] out    Plaintext without IV.
 *                     Minimal buffer length = (inlen - 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext as n 64-bit blocks.
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 *                     or if inlen is not a multiple of 8.
 *                     Output length otherwise.
 */
static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
                                    unsigned char *out,
                                    const unsigned char *in, size_t inlen,
                                    block128_f block)
{
    unsigned char *A, B[16], *R;
    size_t i, j, t;
    inlen -= 8;
    if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
        return 0;
    A = B;
    t = 6 * (inlen >> 3);
    memcpy(A, in, 8);
    memmove(out, in + 8, inlen);
    for (j = 0; j < 6; j++) {
        R = out + inlen - 8;
        for (i = 0; i < inlen; i += 8, t--, R -= 8) {
            A[7] ^= (unsigned char)(t & 0xff);
            if (t > 0xff) {
                A[6] ^= (unsigned char)((t >> 8) & 0xff);
                A[5] ^= (unsigned char)((t >> 16) & 0xff);
                A[4] ^= (unsigned char)((t >> 24) & 0xff);
            }
            memcpy(B + 8, R, 8);
            block(B, B, key);
            memcpy(R, B + 8, 8);
        }
    }
    memcpy(iv, A, 8);
    return inlen;
}

/** Unwrapping according to RFC 3394 section 2.2.2, including the IV check.
 *  The first block of plaintext has to match the supplied IV, otherwise an
 *  error is returned.
 *
 *  @param[in]  key    Key value.
 *  @param[out] iv     IV value to match against. Length = 8 bytes.
 *                     NULL = use default_iv.
 *  @param[out] out    Plaintext without IV.
 *                     Minimal buffer length = (inlen - 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext as n 64-bit blocks.
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
 *                     or if inlen is not a multiple of 8
 *                     or if IV doesn't match expected value.
 *                     Output length otherwise.
 */
size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
                         unsigned char *out, const unsigned char *in,
                         size_t inlen, block128_f block)
{
    size_t ret;
    unsigned char got_iv[8];

    ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
    if (ret == 0)
        return 0;

    if (!iv)
        iv = default_iv;
    if (CRYPTO_memcmp(got_iv, iv, 8)) {
        OPENSSL_cleanse(out, ret);
        return 0;
    }
    return ret;
}

/** Wrapping according to RFC 5649 section 4.1.
 *
 *  @param[in]  key    Key value.
 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 15) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
 *                     Output length if wrapping succeeded.
 */
size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
                           unsigned char *out,
                           const unsigned char *in, size_t inlen,
                           block128_f block)
{
    /* n: number of 64-bit blocks in the padded key data
     *
     * If length of plain text is not a multiple of 8, pad the plain text octet
     * string on the right with octets of zeros, where final length is the
     * smallest multiple of 8 that is greater than length of plain text.
     * If length of plain text is a multiple of 8, then there is no padding. */
    const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
    const size_t padded_len = blocks_padded * 8;
    const size_t padding_len = padded_len - inlen;
    /* RFC 5649 section 3: Alternative Initial Value */
    unsigned char aiv[8];
    int ret;

    /* Section 1: use 32-bit fixed field for plaintext octet length */
    if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
        return 0;

    /* Section 3: Alternative Initial Value */
    if (!icv)
        memcpy(aiv, default_aiv, 4);
    else
        memcpy(aiv, icv, 4);    /* Standard doesn't mention this. */

    aiv[4] = (inlen >> 24) & 0xFF;
    aiv[5] = (inlen >> 16) & 0xFF;
    aiv[6] = (inlen >> 8) & 0xFF;
    aiv[7] = inlen & 0xFF;

    if (padded_len == 8) {
        /*
         * Section 4.1 - special case in step 2: If the padded plaintext
         * contains exactly eight octets, then prepend the AIV and encrypt
         * the resulting 128-bit block using AES in ECB mode.
         */
        memmove(out + 8, in, inlen);
        memcpy(out, aiv, 8);
        memset(out + 8 + inlen, 0, padding_len);
        block(out, out, key);
        ret = 16;               /* AIV + padded input */
    } else {
        memmove(out, in, inlen);
        memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
        ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
    }

    return ret;
}

/** Unwrapping according to RFC 5649 section 4.2.
 *
 *  @param[in]  key    Key value.
 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
 *  @param[out] out    Plaintext. Minimal buffer length = (inlen - 8) bytes.
 *                     Input and output buffers can overlap if block function
 *                     supports that.
 *  @param[in]  in     Ciphertext as n 64-bit blocks.
 *  @param[in]  inlen  Length of in.
 *  @param[in]  block  Block processing function.
 *  @return            0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
 *                     or if inlen is not a multiple of 8
 *                     or if IV and message length indicator doesn't match.
 *                     Output length if unwrapping succeeded and IV matches.
 */
size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
                             unsigned char *out,
                             const unsigned char *in, size_t inlen,
                             block128_f block)
{
    /* n: number of 64-bit blocks in the padded key data */
    size_t n = inlen / 8 - 1;
    size_t padded_len;
    size_t padding_len;
    size_t ptext_len;
    /* RFC 5649 section 3: Alternative Initial Value */
    unsigned char aiv[8];
    static unsigned char zeros[8] = { 0x0 };
    size_t ret;

    /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */
    if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
        return 0;

    if (inlen == 16) {
        /*
         * Section 4.2 - special case in step 1: When n=1, the ciphertext
         * contains exactly two 64-bit blocks and they are decrypted as a
         * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
         * C[1])
         */
        unsigned char buff[16];

        block(in, buff, key);
        memcpy(aiv, buff, 8);
        /* Remove AIV */
        memcpy(out, buff + 8, 8);
        padded_len = 8;
        OPENSSL_cleanse(buff, inlen);
    } else {
        padded_len = inlen - 8;
        ret = crypto_128_unwrap_raw(key, aiv, out, in, inlen, block);
        if (padded_len != ret) {
            OPENSSL_cleanse(out, inlen);
            return 0;
        }
    }

    /*
     * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
     * user-supplied value can be used (even if standard doesn't mention
     * this).
     */
    if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
        || (icv && CRYPTO_memcmp(aiv, icv, 4))) {
        OPENSSL_cleanse(out, inlen);
        return 0;
    }

    /*
     * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
     * LSB(32,AIV).
     */

    ptext_len =   ((unsigned int)aiv[4] << 24)
                | ((unsigned int)aiv[5] << 16)
                | ((unsigned int)aiv[6] <<  8)
                |  (unsigned int)aiv[7];
    if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
        OPENSSL_cleanse(out, inlen);
        return 0;
    }

    /*
     * Check that the rightmost padding_len octets of the output data are
     * zero.
     */
    padding_len = padded_len - ptext_len;
    if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
        OPENSSL_cleanse(out, inlen);
        return 0;
    }

    /* Section 4.2 step 3: Remove padding */
    return ptext_len;
}