1/*
2 * Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10/**  Beware!
11 *
12 *  Following wrapping modes were designed for AES but this implementation
13 *  allows you to use them for any 128 bit block cipher.
14 */
15
16#include "internal/cryptlib.h"
17#include <openssl/modes.h>
18
19/** RFC 3394 section 2.2.3.1 Default Initial Value */
20static const unsigned char default_iv[] = {
21    0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
22};
23
24/** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
25static const unsigned char default_aiv[] = {
26    0xA6, 0x59, 0x59, 0xA6
27};
28
29/** Input size limit: lower than maximum of standards but far larger than
30 *  anything that will be used in practice.
31 */
32#define CRYPTO128_WRAP_MAX (1UL << 31)
33
34/** Wrapping according to RFC 3394 section 2.2.1.
35 *
36 *  @param[in]  key    Key value.
37 *  @param[in]  iv     IV value. Length = 8 bytes. NULL = use default_iv.
38 *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
39 *  @param[in]  inlen  Length of in.
40 *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 8) bytes.
41 *                     Input and output buffers can overlap if block function
42 *                     supports that.
43 *  @param[in]  block  Block processing function.
44 *  @return            0 if inlen does not consist of n 64-bit blocks, n >= 2.
45 *                     or if inlen > CRYPTO128_WRAP_MAX.
46 *                     Output length if wrapping succeeded.
47 */
48size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
49                       unsigned char *out,
50                       const unsigned char *in, size_t inlen,
51                       block128_f block)
52{
53    unsigned char *A, B[16], *R;
54    size_t i, j, t;
55    if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
56        return 0;
57    A = B;
58    t = 1;
59    memmove(out + 8, in, inlen);
60    if (!iv)
61        iv = default_iv;
62
63    memcpy(A, iv, 8);
64
65    for (j = 0; j < 6; j++) {
66        R = out + 8;
67        for (i = 0; i < inlen; i += 8, t++, R += 8) {
68            memcpy(B + 8, R, 8);
69            block(B, B, key);
70            A[7] ^= (unsigned char)(t & 0xff);
71            if (t > 0xff) {
72                A[6] ^= (unsigned char)((t >> 8) & 0xff);
73                A[5] ^= (unsigned char)((t >> 16) & 0xff);
74                A[4] ^= (unsigned char)((t >> 24) & 0xff);
75            }
76            memcpy(R, B + 8, 8);
77        }
78    }
79    memcpy(out, A, 8);
80    return inlen + 8;
81}
82
83/** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
84 *  The IV check (step 3) is responsibility of the caller.
85 *
86 *  @param[in]  key    Key value.
87 *  @param[out] iv     Unchecked IV value. Minimal buffer length = 8 bytes.
88 *  @param[out] out    Plaintext without IV.
89 *                     Minimal buffer length = (inlen - 8) bytes.
90 *                     Input and output buffers can overlap if block function
91 *                     supports that.
92 *  @param[in]  in     Ciphertext as n 64-bit blocks.
93 *  @param[in]  inlen  Length of in.
94 *  @param[in]  block  Block processing function.
95 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
96 *                     or if inlen is not a multiple of 8.
97 *                     Output length otherwise.
98 */
99static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
100                                    unsigned char *out,
101                                    const unsigned char *in, size_t inlen,
102                                    block128_f block)
103{
104    unsigned char *A, B[16], *R;
105    size_t i, j, t;
106    inlen -= 8;
107    if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
108        return 0;
109    A = B;
110    t = 6 * (inlen >> 3);
111    memcpy(A, in, 8);
112    memmove(out, in + 8, inlen);
113    for (j = 0; j < 6; j++) {
114        R = out + inlen - 8;
115        for (i = 0; i < inlen; i += 8, t--, R -= 8) {
116            A[7] ^= (unsigned char)(t & 0xff);
117            if (t > 0xff) {
118                A[6] ^= (unsigned char)((t >> 8) & 0xff);
119                A[5] ^= (unsigned char)((t >> 16) & 0xff);
120                A[4] ^= (unsigned char)((t >> 24) & 0xff);
121            }
122            memcpy(B + 8, R, 8);
123            block(B, B, key);
124            memcpy(R, B + 8, 8);
125        }
126    }
127    memcpy(iv, A, 8);
128    return inlen;
129}
130
131/** Unwrapping according to RFC 3394 section 2.2.2, including the IV check.
132 *  The first block of plaintext has to match the supplied IV, otherwise an
133 *  error is returned.
134 *
135 *  @param[in]  key    Key value.
136 *  @param[out] iv     IV value to match against. Length = 8 bytes.
137 *                     NULL = use default_iv.
138 *  @param[out] out    Plaintext without IV.
139 *                     Minimal buffer length = (inlen - 8) bytes.
140 *                     Input and output buffers can overlap if block function
141 *                     supports that.
142 *  @param[in]  in     Ciphertext as n 64-bit blocks.
143 *  @param[in]  inlen  Length of in.
144 *  @param[in]  block  Block processing function.
145 *  @return            0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
146 *                     or if inlen is not a multiple of 8
147 *                     or if IV doesn't match expected value.
148 *                     Output length otherwise.
149 */
150size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
151                         unsigned char *out, const unsigned char *in,
152                         size_t inlen, block128_f block)
153{
154    size_t ret;
155    unsigned char got_iv[8];
156
157    ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
158    if (ret == 0)
159        return 0;
160
161    if (!iv)
162        iv = default_iv;
163    if (CRYPTO_memcmp(got_iv, iv, 8)) {
164        OPENSSL_cleanse(out, ret);
165        return 0;
166    }
167    return ret;
168}
169
170/** Wrapping according to RFC 5649 section 4.1.
171 *
172 *  @param[in]  key    Key value.
173 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
174 *  @param[out] out    Ciphertext. Minimal buffer length = (inlen + 15) bytes.
175 *                     Input and output buffers can overlap if block function
176 *                     supports that.
177 *  @param[in]  in     Plaintext as n 64-bit blocks, n >= 2.
178 *  @param[in]  inlen  Length of in.
179 *  @param[in]  block  Block processing function.
180 *  @return            0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
181 *                     Output length if wrapping succeeded.
182 */
183size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
184                           unsigned char *out,
185                           const unsigned char *in, size_t inlen,
186                           block128_f block)
187{
188    /* n: number of 64-bit blocks in the padded key data
189     *
190     * If length of plain text is not a multiple of 8, pad the plain text octet
191     * string on the right with octets of zeros, where final length is the
192     * smallest multiple of 8 that is greater than length of plain text.
193     * If length of plain text is a multiple of 8, then there is no padding. */
194    const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
195    const size_t padded_len = blocks_padded * 8;
196    const size_t padding_len = padded_len - inlen;
197    /* RFC 5649 section 3: Alternative Initial Value */
198    unsigned char aiv[8];
199    int ret;
200
201    /* Section 1: use 32-bit fixed field for plaintext octet length */
202    if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
203        return 0;
204
205    /* Section 3: Alternative Initial Value */
206    if (!icv)
207        memcpy(aiv, default_aiv, 4);
208    else
209        memcpy(aiv, icv, 4);    /* Standard doesn't mention this. */
210
211    aiv[4] = (inlen >> 24) & 0xFF;
212    aiv[5] = (inlen >> 16) & 0xFF;
213    aiv[6] = (inlen >> 8) & 0xFF;
214    aiv[7] = inlen & 0xFF;
215
216    if (padded_len == 8) {
217        /*
218         * Section 4.1 - special case in step 2: If the padded plaintext
219         * contains exactly eight octets, then prepend the AIV and encrypt
220         * the resulting 128-bit block using AES in ECB mode.
221         */
222        memmove(out + 8, in, inlen);
223        memcpy(out, aiv, 8);
224        memset(out + 8 + inlen, 0, padding_len);
225        block(out, out, key);
226        ret = 16;               /* AIV + padded input */
227    } else {
228        memmove(out, in, inlen);
229        memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
230        ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
231    }
232
233    return ret;
234}
235
236/** Unwrapping according to RFC 5649 section 4.2.
237 *
238 *  @param[in]  key    Key value.
239 *  @param[in]  icv    (Non-standard) IV, 4 bytes. NULL = use default_aiv.
240 *  @param[out] out    Plaintext. Minimal buffer length = (inlen - 8) bytes.
241 *                     Input and output buffers can overlap if block function
242 *                     supports that.
243 *  @param[in]  in     Ciphertext as n 64-bit blocks.
244 *  @param[in]  inlen  Length of in.
245 *  @param[in]  block  Block processing function.
246 *  @return            0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
247 *                     or if inlen is not a multiple of 8
248 *                     or if IV and message length indicator doesn't match.
249 *                     Output length if unwrapping succeeded and IV matches.
250 */
251size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
252                             unsigned char *out,
253                             const unsigned char *in, size_t inlen,
254                             block128_f block)
255{
256    /* n: number of 64-bit blocks in the padded key data */
257    size_t n = inlen / 8 - 1;
258    size_t padded_len;
259    size_t padding_len;
260    size_t ptext_len;
261    /* RFC 5649 section 3: Alternative Initial Value */
262    unsigned char aiv[8];
263    static unsigned char zeros[8] = { 0x0 };
264    size_t ret;
265
266    /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */
267    if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
268        return 0;
269
270    if (inlen == 16) {
271        /*
272         * Section 4.2 - special case in step 1: When n=1, the ciphertext
273         * contains exactly two 64-bit blocks and they are decrypted as a
274         * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
275         * C[1])
276         */
277        unsigned char buff[16];
278
279        block(in, buff, key);
280        memcpy(aiv, buff, 8);
281        /* Remove AIV */
282        memcpy(out, buff + 8, 8);
283        padded_len = 8;
284        OPENSSL_cleanse(buff, inlen);
285    } else {
286        padded_len = inlen - 8;
287        ret = crypto_128_unwrap_raw(key, aiv, out, in, inlen, block);
288        if (padded_len != ret) {
289            OPENSSL_cleanse(out, inlen);
290            return 0;
291        }
292    }
293
294    /*
295     * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
296     * user-supplied value can be used (even if standard doesn't mention
297     * this).
298     */
299    if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
300        || (icv && CRYPTO_memcmp(aiv, icv, 4))) {
301        OPENSSL_cleanse(out, inlen);
302        return 0;
303    }
304
305    /*
306     * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
307     * LSB(32,AIV).
308     */
309
310    ptext_len =   ((unsigned int)aiv[4] << 24)
311                | ((unsigned int)aiv[5] << 16)
312                | ((unsigned int)aiv[6] <<  8)
313                |  (unsigned int)aiv[7];
314    if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
315        OPENSSL_cleanse(out, inlen);
316        return 0;
317    }
318
319    /*
320     * Check that the rightmost padding_len octets of the output data are
321     * zero.
322     */
323    padding_len = padded_len - ptext_len;
324    if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
325        OPENSSL_cleanse(out, inlen);
326        return 0;
327    }
328
329    /* Section 4.2 step 3: Remove padding */
330    return ptext_len;
331}
332