xref: /openssl/demos/kdf/scrypt.c (revision 86db9588)
1 /*
2  * Copyright 2021-2023 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 #include <stdio.h>
11 #include <openssl/core_names.h>
12 #include <openssl/crypto.h>
13 #include <openssl/kdf.h>
14 #include <openssl/obj_mac.h>
15 #include <openssl/params.h>
16 
17 /*
18  * test vector from
19  * https://datatracker.ietf.org/doc/html/rfc7914
20  */
21 
22 /*
23  * Hard coding a password into an application is very bad.
24  * It is done here solely for educational purposes.
25  */
26 static unsigned char password[] = {
27     'p', 'a', 's', 's', 'w', 'o', 'r', 'd'
28 };
29 
30 /*
31  * The salt is better not being hard coded too.  Each password should have a
32  * different salt if possible.  The salt is not considered secret information
33  * and is safe to store with an encrypted password.
34  */
35 static unsigned char scrypt_salt[] = {
36     'N', 'a', 'C', 'l'
37 };
38 
39 /*
40  * The SCRYPT parameters can be variable or hard coded.  The disadvantage with
41  * hard coding them is that they cannot easily be adjusted for future
42  * technological improvements appear.
43  */
44 static unsigned int scrypt_n = 1024;
45 static unsigned int scrypt_r = 8;
46 static unsigned int scrypt_p = 16;
47 
48 static const unsigned char expected_output[] = {
49 
50     0xfd, 0xba, 0xbe, 0x1c, 0x9d, 0x34, 0x72, 0x00,
51     0x78, 0x56, 0xe7, 0x19, 0x0d, 0x01, 0xe9, 0xfe,
52     0x7c, 0x6a, 0xd7, 0xcb, 0xc8, 0x23, 0x78, 0x30,
53     0xe7, 0x73, 0x76, 0x63, 0x4b, 0x37, 0x31, 0x62,
54     0x2e, 0xaf, 0x30, 0xd9, 0x2e, 0x22, 0xa3, 0x88,
55     0x6f, 0xf1, 0x09, 0x27, 0x9d, 0x98, 0x30, 0xda,
56     0xc7, 0x27, 0xaf, 0xb9, 0x4a, 0x83, 0xee, 0x6d,
57     0x83, 0x60, 0xcb, 0xdf, 0xa2, 0xcc, 0x06, 0x40
58 };
59 
main(int argc,char ** argv)60 int main(int argc, char **argv)
61 {
62     int ret = EXIT_FAILURE;
63     EVP_KDF *kdf = NULL;
64     EVP_KDF_CTX *kctx = NULL;
65     unsigned char out[64];
66     OSSL_PARAM params[6], *p = params;
67     OSSL_LIB_CTX *library_context = NULL;
68 
69     library_context = OSSL_LIB_CTX_new();
70     if (library_context == NULL) {
71         fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
72         goto end;
73     }
74 
75     /* Fetch the key derivation function implementation */
76     kdf = EVP_KDF_fetch(library_context, "SCRYPT", NULL);
77     if (kdf == NULL) {
78         fprintf(stderr, "EVP_KDF_fetch() returned NULL\n");
79         goto end;
80     }
81 
82     /* Create a context for the key derivation operation */
83     kctx = EVP_KDF_CTX_new(kdf);
84     if (kctx == NULL) {
85         fprintf(stderr, "EVP_KDF_CTX_new() returned NULL\n");
86         goto end;
87     }
88 
89     /* Set password */
90     *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_PASSWORD, password,
91                                              sizeof(password));
92     /* Set salt */
93     *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT, scrypt_salt,
94                                              sizeof(scrypt_salt));
95     /* Set N (default 1048576) */
96     *p++ = OSSL_PARAM_construct_uint(OSSL_KDF_PARAM_SCRYPT_N, &scrypt_n);
97     /* Set R (default 8) */
98     *p++ = OSSL_PARAM_construct_uint(OSSL_KDF_PARAM_SCRYPT_R, &scrypt_r);
99     /* Set P (default 1) */
100     *p++ = OSSL_PARAM_construct_uint(OSSL_KDF_PARAM_SCRYPT_P, &scrypt_p);
101     *p = OSSL_PARAM_construct_end();
102 
103     /* Derive the key */
104     if (EVP_KDF_derive(kctx, out, sizeof(out), params) != 1) {
105         fprintf(stderr, "EVP_KDF_derive() failed\n");
106         goto end;
107     }
108 
109     if (CRYPTO_memcmp(expected_output, out, sizeof(expected_output)) != 0) {
110         fprintf(stderr, "Generated key does not match expected value\n");
111         goto end;
112     }
113 
114     printf("Success\n");
115 
116     ret = EXIT_SUCCESS;
117 end:
118     EVP_KDF_CTX_free(kctx);
119     EVP_KDF_free(kdf);
120     OSSL_LIB_CTX_free(library_context);
121     return ret;
122 }
123