2 * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
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
13 #include <openssl/hmac.h>
14 #include <openssl/evp.h>
15 #include <openssl/kdf.h>
16 #include "internal/cryptlib.h"
17 #include "internal/evp_int.h"
18 #include "kdf_local.h"
20 #define HKDF_MAXBUF 1024
22 static void kdf_hkdf_reset(EVP_KDF_IMPL *impl);
23 static int HKDF(const EVP_MD *evp_md,
24 const unsigned char *salt, size_t salt_len,
25 const unsigned char *key, size_t key_len,
26 const unsigned char *info, size_t info_len,
27 unsigned char *okm, size_t okm_len);
28 static int HKDF_Extract(const EVP_MD *evp_md,
29 const unsigned char *salt, size_t salt_len,
30 const unsigned char *key, size_t key_len,
31 unsigned char *prk, size_t prk_len);
32 static int HKDF_Expand(const EVP_MD *evp_md,
33 const unsigned char *prk, size_t prk_len,
34 const unsigned char *info, size_t info_len,
35 unsigned char *okm, size_t okm_len);
37 struct evp_kdf_impl_st {
44 unsigned char info[HKDF_MAXBUF];
48 static EVP_KDF_IMPL *kdf_hkdf_new(void)
52 if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL)
53 KDFerr(KDF_F_KDF_HKDF_NEW, ERR_R_MALLOC_FAILURE);
57 static void kdf_hkdf_free(EVP_KDF_IMPL *impl)
63 static void kdf_hkdf_reset(EVP_KDF_IMPL *impl)
65 OPENSSL_free(impl->salt);
66 OPENSSL_clear_free(impl->key, impl->key_len);
67 OPENSSL_cleanse(impl->info, impl->info_len);
68 memset(impl, 0, sizeof(*impl));
71 static int kdf_hkdf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
73 const unsigned char *p;
78 case EVP_KDF_CTRL_SET_MD:
79 md = va_arg(args, const EVP_MD *);
86 case EVP_KDF_CTRL_SET_HKDF_MODE:
87 impl->mode = va_arg(args, int);
90 case EVP_KDF_CTRL_SET_SALT:
91 p = va_arg(args, const unsigned char *);
92 len = va_arg(args, size_t);
93 if (len == 0 || p == NULL)
96 OPENSSL_free(impl->salt);
97 impl->salt = OPENSSL_memdup(p, len);
98 if (impl->salt == NULL)
101 impl->salt_len = len;
104 case EVP_KDF_CTRL_SET_KEY:
105 p = va_arg(args, const unsigned char *);
106 len = va_arg(args, size_t);
107 OPENSSL_clear_free(impl->key, impl->key_len);
108 impl->key = OPENSSL_memdup(p, len);
109 if (impl->key == NULL)
115 case EVP_KDF_CTRL_RESET_HKDF_INFO:
116 OPENSSL_cleanse(impl->info, impl->info_len);
120 case EVP_KDF_CTRL_ADD_HKDF_INFO:
121 p = va_arg(args, const unsigned char *);
122 len = va_arg(args, size_t);
123 if (len == 0 || p == NULL)
126 if (len > (HKDF_MAXBUF - impl->info_len))
129 memcpy(impl->info + impl->info_len, p, len);
130 impl->info_len += len;
138 static int kdf_hkdf_ctrl_str(EVP_KDF_IMPL *impl, const char *type,
141 if (strcmp(type, "mode") == 0) {
144 if (strcmp(value, "EXTRACT_AND_EXPAND") == 0)
145 mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
146 else if (strcmp(value, "EXTRACT_ONLY") == 0)
147 mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
148 else if (strcmp(value, "EXPAND_ONLY") == 0)
149 mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
153 return call_ctrl(kdf_hkdf_ctrl, impl, EVP_KDF_CTRL_SET_HKDF_MODE, mode);
156 if (strcmp(type, "digest") == 0)
157 return kdf_md2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_MD, value);
159 if (strcmp(type, "salt") == 0)
160 return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value);
162 if (strcmp(type, "hexsalt") == 0)
163 return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value);
165 if (strcmp(type, "key") == 0)
166 return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value);
168 if (strcmp(type, "hexkey") == 0)
169 return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value);
171 if (strcmp(type, "info") == 0)
172 return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO,
175 if (strcmp(type, "hexinfo") == 0)
176 return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO,
182 static size_t kdf_hkdf_size(EVP_KDF_IMPL *impl)
184 if (impl->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
187 if (impl->md == NULL) {
188 KDFerr(KDF_F_KDF_HKDF_SIZE, KDF_R_MISSING_MESSAGE_DIGEST);
191 return EVP_MD_size(impl->md);
194 static int kdf_hkdf_derive(EVP_KDF_IMPL *impl, unsigned char *key,
197 if (impl->md == NULL) {
198 KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST);
201 if (impl->key == NULL) {
202 KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_KEY);
206 switch (impl->mode) {
207 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
208 return HKDF(impl->md, impl->salt, impl->salt_len, impl->key,
209 impl->key_len, impl->info, impl->info_len, key,
212 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
213 return HKDF_Extract(impl->md, impl->salt, impl->salt_len, impl->key,
214 impl->key_len, key, keylen);
216 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
217 return HKDF_Expand(impl->md, impl->key, impl->key_len, impl->info,
218 impl->info_len, key, keylen);
225 const EVP_KDF_METHOD hkdf_kdf_meth = {
236 static int HKDF(const EVP_MD *evp_md,
237 const unsigned char *salt, size_t salt_len,
238 const unsigned char *key, size_t key_len,
239 const unsigned char *info, size_t info_len,
240 unsigned char *okm, size_t okm_len)
242 unsigned char prk[EVP_MAX_MD_SIZE];
244 size_t prk_len = EVP_MD_size(evp_md);
246 if (!HKDF_Extract(evp_md, salt, salt_len, key, key_len, prk, prk_len))
249 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
250 OPENSSL_cleanse(prk, sizeof(prk));
255 static int HKDF_Extract(const EVP_MD *evp_md,
256 const unsigned char *salt, size_t salt_len,
257 const unsigned char *key, size_t key_len,
258 unsigned char *prk, size_t prk_len)
260 if (prk_len != (size_t)EVP_MD_size(evp_md)) {
261 KDFerr(KDF_F_HKDF_EXTRACT, KDF_R_WRONG_OUTPUT_BUFFER_SIZE);
264 return HMAC(evp_md, salt, salt_len, key, key_len, prk, NULL) != NULL;
267 static int HKDF_Expand(const EVP_MD *evp_md,
268 const unsigned char *prk, size_t prk_len,
269 const unsigned char *info, size_t info_len,
270 unsigned char *okm, size_t okm_len)
275 unsigned char prev[EVP_MAX_MD_SIZE];
276 size_t done_len = 0, dig_len = EVP_MD_size(evp_md);
277 size_t n = okm_len / dig_len;
279 if (okm_len % dig_len)
282 if (n > 255 || okm == NULL)
285 if ((hmac = HMAC_CTX_new()) == NULL)
288 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
291 for (i = 1; i <= n; i++) {
293 const unsigned char ctr = i;
296 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
299 if (!HMAC_Update(hmac, prev, dig_len))
303 if (!HMAC_Update(hmac, info, info_len))
306 if (!HMAC_Update(hmac, &ctr, 1))
309 if (!HMAC_Final(hmac, prev, NULL))
312 copy_len = (done_len + dig_len > okm_len) ?
316 memcpy(okm + done_len, prev, copy_len);
318 done_len += copy_len;
323 OPENSSL_cleanse(prev, sizeof(prev));