1 // Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include <openssl/cipher.h>
16
17 #include <assert.h>
18
19 #include <openssl/digest.h>
20 #include <openssl/mem.h>
21
22
EVP_BytesToKey(const EVP_CIPHER * type,const EVP_MD * md,const uint8_t salt[8],const uint8_t * data,size_t data_len,unsigned count,uint8_t * key,uint8_t * iv)23 int EVP_BytesToKey(const EVP_CIPHER *type, const EVP_MD *md,
24 const uint8_t salt[8], const uint8_t *data, size_t data_len,
25 unsigned count, uint8_t *key, uint8_t *iv) {
26 uint8_t md_buf[EVP_MAX_MD_SIZE];
27 unsigned addmd = 0;
28 unsigned mds = 0, i;
29 int rv = 0;
30
31 unsigned nkey = EVP_CIPHER_key_length(type);
32 unsigned niv = EVP_CIPHER_iv_length(type);
33
34 assert(nkey <= EVP_MAX_KEY_LENGTH);
35 assert(niv <= EVP_MAX_IV_LENGTH);
36
37 if (data == nullptr) {
38 return nkey;
39 }
40
41 bssl::ScopedEVP_MD_CTX c;
42 for (;;) {
43 if (!EVP_DigestInit_ex(c.get(), md, nullptr)) {
44 goto err;
45 }
46 if (addmd++) {
47 if (!EVP_DigestUpdate(c.get(), md_buf, mds)) {
48 goto err;
49 }
50 }
51 if (!EVP_DigestUpdate(c.get(), data, data_len)) {
52 goto err;
53 }
54 if (salt != nullptr) {
55 if (!EVP_DigestUpdate(c.get(), salt, 8)) {
56 goto err;
57 }
58 }
59 if (!EVP_DigestFinal_ex(c.get(), md_buf, &mds)) {
60 goto err;
61 }
62
63 for (i = 1; i < count; i++) {
64 if (!EVP_DigestInit_ex(c.get(), md, nullptr) ||
65 !EVP_DigestUpdate(c.get(), md_buf, mds) ||
66 !EVP_DigestFinal_ex(c.get(), md_buf, &mds)) {
67 goto err;
68 }
69 }
70
71 i = 0;
72 if (nkey) {
73 for (;;) {
74 if (nkey == 0 || i == mds) {
75 break;
76 }
77 if (key != nullptr) {
78 *(key++) = md_buf[i];
79 }
80 nkey--;
81 i++;
82 }
83 }
84
85 if (niv && i != mds) {
86 for (;;) {
87 if (niv == 0 || i == mds) {
88 break;
89 }
90 if (iv != nullptr) {
91 *(iv++) = md_buf[i];
92 }
93 niv--;
94 i++;
95 }
96 }
97 if (nkey == 0 && niv == 0) {
98 break;
99 }
100 }
101 rv = EVP_CIPHER_key_length(type);
102
103 err:
104 OPENSSL_cleanse(md_buf, EVP_MAX_MD_SIZE);
105 return rv;
106 }
107