gvpe/src/hkdf.C

/*
    hkdf.C -- RFC 5869 HKDF implementation
    Copyright (C) 2013      Marc Lehmann <gvpe@schmorp.de>
 
    This file is part of GVPE.

    GVPE is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
    Free Software Foundation; either version 3 of the License, or (at your
    option) any later version.
   
    This program is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
    Public License for more details.
   
    You should have received a copy of the GNU General Public License along
    with this program; if not, see <http://www.gnu.org/licenses/>.
   
    Additional permission under GNU GPL version 3 section 7
   
    If you modify this Program, or any covered work, by linking or
    combining it with the OpenSSL project's OpenSSL library (or a modified
    version of that library), containing parts covered by the terms of the
    OpenSSL or SSLeay licenses, the licensors of this Program grant you
    additional permission to convey the resulting work.  Corresponding
    Source for a non-source form of such a combination shall include the
    source code for the parts of OpenSSL used as well as that of the
    covered work.
*/

#include "config.h"

#include <cstring>

#include <openssl/rand.h>
#include <openssl/hmac.h>

#include "util.h"
#include "hkdf.h"

hkdf::hkdf (const void *salt, int len, const EVP_MD *xtr_hash)
{
  HMAC_CTX_init (&ctx);

  if (!salt)
    {
      memset (prk, 0, sizeof prk);
      salt = prk;
      len  = EVP_MD_size (xtr_hash);
    }

  require (HMAC_Init_ex (&ctx, salt, len, xtr_hash, 0));
}

hkdf::~hkdf ()
{
  HMAC_CTX_cleanup (&ctx);
}

void
hkdf::extract (const void *ikm, int len)
{
  require (HMAC_Update (&ctx, (u8 *)ikm, len));
}

void
hkdf::extract_done (const EVP_MD *prf_hash)
{
  require (HMAC_Final (&ctx, prk, 0));
  require (HMAC_Init_ex (&ctx, 0, 0, prf_hash, 0));
}

void
hkdf::expand (void *okm, int len, const void *info, int infolen)
{
  u8 tn[sizeof prk];
  u8 iter = 0;
  int md_size = HMAC_size (&ctx);

  while (len)
    {
      require (HMAC_Init_ex (&ctx, prk, md_size, 0, 0));

      if (iter)
        require (HMAC_Update (&ctx, tn, md_size));

      require (HMAC_Update (&ctx, (u8 *)info, infolen));


      ++iter;
      require (iter);

      require (HMAC_Update (&ctx, &iter, 1));

      require (HMAC_Final (&ctx, tn, 0));

      int ol = len > md_size ? md_size : len;

      memcpy (okm, tn, ol);

      okm = (void *)(ol + (char *)okm);
      len -= ol;
    }
}

// try to verify all test vectors from the RFC
// since I implemented the hkdf myself, and I am no crypto expert,
// we run verification on every startup.
void
hkdf::verify ()
{
  struct unhex
  {
    u8 *p;
    int l;

    u8 s[256];

    unhex (const char *hs)
    {
      l = 0;
      p = 0;

      if (!hs)
        return;

      p = s;

      while (*hs)
        {
          int d1 = *hs >= '0' && *hs <= '9' ? *hs - '0' : *hs - 'a' + 10; ++hs;
          int d2 = *hs >= '0' && *hs <= '9' ? *hs - '0' : *hs - 'a' + 10; ++hs;

          *p++ = d1 * 16 + d2;
          ++l;
        }

      p = s;
    }
  };

  const struct hkdf_test
  {
     int hash;
     const char *IKM, *salt, *info;
     const char *PRK, *OKM;
  } tests[] = {
    { // 0
      256,
      "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
      "000102030405060708090a0b0c",
      "f0f1f2f3f4f5f6f7f8f9",
      "077709362c2e32df0ddc3f0dc47bba63"
      "90b6c73bb50f9c3122ec844ad7c2b3e5",
      "3cb25f25faacd57a90434f64d0362f2a"
      "2d2d0a90cf1a5a4c5db02d56ecc4c5bf"
      "34007208d5b887185865"
    }, { // 1
      256,
      "000102030405060708090a0b0c0d0e0f"
      "101112131415161718191a1b1c1d1e1f"
      "202122232425262728292a2b2c2d2e2f"
      "303132333435363738393a3b3c3d3e3f"
      "404142434445464748494a4b4c4d4e4f",
      "606162636465666768696a6b6c6d6e6f"
      "707172737475767778797a7b7c7d7e7f"
      "808182838485868788898a8b8c8d8e8f"
      "909192939495969798999a9b9c9d9e9f"
      "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
      "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
      "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
      "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
      "e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
      "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
      "06a6b88c5853361a06104c9ceb35b45c"
      "ef760014904671014a193f40c15fc244",
      "b11e398dc80327a1c8e7f78c596a4934"
      "4f012eda2d4efad8a050cc4c19afa97c"
      "59045a99cac7827271cb41c65e590e09"
      "da3275600c2f09b8367793a9aca3db71"
      "cc30c58179ec3e87c14c01d5c1f3434f"
      "1d87"
    }, { // 2
      256,
      "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
      "",
      "",
      "19ef24a32c717b167f33a91d6f648bdf"
      "96596776afdb6377ac434c1c293ccb04",
      "8da4e775a563c18f715f802a063c5a31"
      "b8a11f5c5ee1879ec3454e5f3c738d2d"
      "9d201395faa4b61a96c8"
    }, { // 3
      1,
      "0b0b0b0b0b0b0b0b0b0b0b",
      "000102030405060708090a0b0c",
      "f0f1f2f3f4f5f6f7f8f9",
      "9b6c18c432a7bf8f0e71c8eb88f4b30baa2ba243",
      "085a01ea1b10f36933068b56efa5ad81"
      "a4f14b822f5b091568a9cdd4f155fda2"
      "c22e422478d305f3f896"
    }, { // 4
      1,
      "000102030405060708090a0b0c0d0e0f"
      "101112131415161718191a1b1c1d1e1f"
      "202122232425262728292a2b2c2d2e2f"
      "303132333435363738393a3b3c3d3e3f"
      "404142434445464748494a4b4c4d4e4f",
      "606162636465666768696a6b6c6d6e6f"
      "707172737475767778797a7b7c7d7e7f"
      "808182838485868788898a8b8c8d8e8f"
      "909192939495969798999a9b9c9d9e9f"
      "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
      "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
      "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
      "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
      "e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
      "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
      "8adae09a2a307059478d309b26c4115a224cfaf6",
      "0bd770a74d1160f7c9f12cd5912a06eb"
      "ff6adcae899d92191fe4305673ba2ffe"
      "8fa3f1a4e5ad79f3f334b3b202b2173c"
      "486ea37ce3d397ed034c7f9dfeb15c5e"
      "927336d0441f4c4300e2cff0d0900b52"
      "d3b4"
    }, { // 5
      1,
      "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
      "",
      "",
      "da8c8a73c7fa77288ec6f5e7c297786aa0d32d01",
      "0ac1af7002b3d761d1e55298da9d0506"
      "b9ae52057220a306e07b6b87e8df21d0"
      "ea00033de03984d34918"
    }, { // 6
      1,
      "0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c",
      0,
      "",
      "2adccada18779e7c2077ad2eb19d3f3e731385dd",
      "2c91117204d745f3500d636a62f64f0a"
      "b3bae548aa53d423b0d1f27ebba6f5e5"
      "673a081d70cce7acfc48"
    }
  };

  for (int i = 0; i < sizeof (tests) / sizeof (tests[0]); ++i)
    {
      const hkdf_test &test = tests[i];

      unhex salt (test.salt);
      unhex ikm (test.IKM);
      unhex info (test.info);
      unhex prk_correct (test.PRK);
      unhex okm_correct (test.OKM);

      char okm[256];

      hkdf h (salt.p, salt.l, test.hash == 1 ? EVP_sha1 () : EVP_sha256 ());
      h.extract (ikm.p, ikm.l);
      h.extract_done ();
      h.expand (okm, okm_correct.l, info.p, info.l);

      require (!memcmp (h.prk, prk_correct.p, prk_correct.l));
      require (!memcmp (okm  , okm_correct.p, okm_correct.l));
    }
}

Revision:	1.2
Committed:	Wed Jul 17 04:36:03 2013 UTC (10 years, 10 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+5 -4 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
2			hkdf.C -- RFC 5869 HKDF implementation
3			Copyright (C) 2013 Marc Lehmann <gvpe@schmorp.de>
4
5			This file is part of GVPE.
6
7			GVPE is free software; you can redistribute it and/or modify it
8			under the terms of the GNU General Public License as published by the
9			Free Software Foundation; either version 3 of the License, or (at your
10			option) any later version.
11
12			This program is distributed in the hope that it will be useful, but
13			WITHOUT ANY WARRANTY; without even the implied warranty of
14			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
15			Public License for more details.
16
17			You should have received a copy of the GNU General Public License along
18			with this program; if not, see <http://www.gnu.org/licenses/>.
19
20			Additional permission under GNU GPL version 3 section 7
21
22			If you modify this Program, or any covered work, by linking or
23			combining it with the OpenSSL project's OpenSSL library (or a modified
24			version of that library), containing parts covered by the terms of the
25			OpenSSL or SSLeay licenses, the licensors of this Program grant you
26			additional permission to convey the resulting work. Corresponding
27			Source for a non-source form of such a combination shall include the
28			source code for the parts of OpenSSL used as well as that of the
29			covered work.
30			*/
31
32			#include "config.h"
33
34			#include <cstring>
35
36			#include <openssl/rand.h>
37			#include <openssl/hmac.h>
38
39			#include "util.h"
40			#include "hkdf.h"
41
42	root	1.2	hkdf::hkdf (const void salt, int len, const EVP_MD xtr_hash)
43	root	1.1	{
44			HMAC_CTX_init (&ctx);
45
46			if (!salt)
47			{
48			memset (prk, 0, sizeof prk);
49			salt = prk;
50	root	1.2	len = EVP_MD_size (xtr_hash);
51	root	1.1	}
52
53	root	1.2	require (HMAC_Init_ex (&ctx, salt, len, xtr_hash, 0));
54	root	1.1	}
55
56			hkdf::~hkdf ()
57			{
58			HMAC_CTX_cleanup (&ctx);
59			}
60
61			void
62			hkdf::extract (const void *ikm, int len)
63			{
64			require (HMAC_Update (&ctx, (u8 *)ikm, len));
65			}
66
67			void
68	root	1.2	hkdf::extract_done (const EVP_MD *prf_hash)
69	root	1.1	{
70			require (HMAC_Final (&ctx, prk, 0));
71	root	1.2	require (HMAC_Init_ex (&ctx, 0, 0, prf_hash, 0));
72	root	1.1	}
73
74			void
75			hkdf::expand (void okm, int len, const void info, int infolen)
76			{
77			u8 tn[sizeof prk];
78			u8 iter = 0;
79			int md_size = HMAC_size (&ctx);
80
81			while (len)
82			{
83			require (HMAC_Init_ex (&ctx, prk, md_size, 0, 0));
84
85			if (iter)
86			require (HMAC_Update (&ctx, tn, md_size));
87
88			require (HMAC_Update (&ctx, (u8 *)info, infolen));
89
90
91			++iter;
92			require (iter);
93
94			require (HMAC_Update (&ctx, &iter, 1));
95
96			require (HMAC_Final (&ctx, tn, 0));
97
98			int ol = len > md_size ? md_size : len;
99
100			memcpy (okm, tn, ol);
101
102			okm = (void )(ol + (char )okm);
103			len -= ol;
104			}
105			}
106
107			// try to verify all test vectors from the RFC
108			// since I implemented the hkdf myself, and I am no crypto expert,
109			// we run verification on every startup.
110			void
111			hkdf::verify ()
112			{
113			struct unhex
114			{
115			u8 *p;
116			int l;
117
118			u8 s[256];
119
120			unhex (const char *hs)
121			{
122			l = 0;
123			p = 0;
124
125			if (!hs)
126			return;
127
128			p = s;
129
130			while (*hs)
131			{
132			int d1 = hs >= '0' && hs <= '9' ? hs - '0' : hs - 'a' + 10; ++hs;
133			int d2 = hs >= '0' && hs <= '9' ? hs - '0' : hs - 'a' + 10; ++hs;
134
135			p++ = d1 16 + d2;
136			++l;
137			}
138
139			p = s;
140			}
141			};
142
143			const struct hkdf_test
144			{
145			int hash;
146			const char IKM, salt, *info;
147			const char PRK, OKM;
148			} tests[] = {
149			{ // 0
150			256,
151			"0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
152			"000102030405060708090a0b0c",
153			"f0f1f2f3f4f5f6f7f8f9",
154			"077709362c2e32df0ddc3f0dc47bba63"
155			"90b6c73bb50f9c3122ec844ad7c2b3e5",
156			"3cb25f25faacd57a90434f64d0362f2a"
157			"2d2d0a90cf1a5a4c5db02d56ecc4c5bf"
158			"34007208d5b887185865"
159			}, { // 1
160			256,
161			"000102030405060708090a0b0c0d0e0f"
162			"101112131415161718191a1b1c1d1e1f"
163			"202122232425262728292a2b2c2d2e2f"
164			"303132333435363738393a3b3c3d3e3f"
165			"404142434445464748494a4b4c4d4e4f",
166			"606162636465666768696a6b6c6d6e6f"
167			"707172737475767778797a7b7c7d7e7f"
168			"808182838485868788898a8b8c8d8e8f"
169			"909192939495969798999a9b9c9d9e9f"
170			"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
171			"b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
172			"c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
173			"d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
174			"e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
175			"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
176			"06a6b88c5853361a06104c9ceb35b45c"
177			"ef760014904671014a193f40c15fc244",
178			"b11e398dc80327a1c8e7f78c596a4934"
179			"4f012eda2d4efad8a050cc4c19afa97c"
180			"59045a99cac7827271cb41c65e590e09"
181			"da3275600c2f09b8367793a9aca3db71"
182			"cc30c58179ec3e87c14c01d5c1f3434f"
183			"1d87"
184			}, { // 2
185			256,
186			"0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
187			"",
188			"",
189			"19ef24a32c717b167f33a91d6f648bdf"
190			"96596776afdb6377ac434c1c293ccb04",
191			"8da4e775a563c18f715f802a063c5a31"
192			"b8a11f5c5ee1879ec3454e5f3c738d2d"
193			"9d201395faa4b61a96c8"
194			}, { // 3
195			1,
196			"0b0b0b0b0b0b0b0b0b0b0b",
197			"000102030405060708090a0b0c",
198			"f0f1f2f3f4f5f6f7f8f9",
199			"9b6c18c432a7bf8f0e71c8eb88f4b30baa2ba243",
200			"085a01ea1b10f36933068b56efa5ad81"
201			"a4f14b822f5b091568a9cdd4f155fda2"
202			"c22e422478d305f3f896"
203			}, { // 4
204			1,
205			"000102030405060708090a0b0c0d0e0f"
206			"101112131415161718191a1b1c1d1e1f"
207			"202122232425262728292a2b2c2d2e2f"
208			"303132333435363738393a3b3c3d3e3f"
209			"404142434445464748494a4b4c4d4e4f",
210			"606162636465666768696a6b6c6d6e6f"
211			"707172737475767778797a7b7c7d7e7f"
212			"808182838485868788898a8b8c8d8e8f"
213			"909192939495969798999a9b9c9d9e9f"
214			"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf",
215			"b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
216			"c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
217			"d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
218			"e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
219			"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
220			"8adae09a2a307059478d309b26c4115a224cfaf6",
221			"0bd770a74d1160f7c9f12cd5912a06eb"
222			"ff6adcae899d92191fe4305673ba2ffe"
223			"8fa3f1a4e5ad79f3f334b3b202b2173c"
224			"486ea37ce3d397ed034c7f9dfeb15c5e"
225			"927336d0441f4c4300e2cff0d0900b52"
226			"d3b4"
227			}, { // 5
228			1,
229			"0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
230			"",
231			"",
232			"da8c8a73c7fa77288ec6f5e7c297786aa0d32d01",
233			"0ac1af7002b3d761d1e55298da9d0506"
234			"b9ae52057220a306e07b6b87e8df21d0"
235			"ea00033de03984d34918"
236			}, { // 6
237			1,
238			"0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c0c",
239			0,
240			"",
241			"2adccada18779e7c2077ad2eb19d3f3e731385dd",
242			"2c91117204d745f3500d636a62f64f0a"
243			"b3bae548aa53d423b0d1f27ebba6f5e5"
244			"673a081d70cce7acfc48"
245			}
246			};
247
248			for (int i = 0; i < sizeof (tests) / sizeof (tests[0]); ++i)
249			{
250			const hkdf_test &test = tests[i];
251
252			unhex salt (test.salt);
253			unhex ikm (test.IKM);
254			unhex info (test.info);
255			unhex prk_correct (test.PRK);
256			unhex okm_correct (test.OKM);
257
258			char okm[256];
259
260			hkdf h (salt.p, salt.l, test.hash == 1 ? EVP_sha1 () : EVP_sha256 ());
261			h.extract (ikm.p, ikm.l);
262			h.extract_done ();
263			h.expand (okm, okm_correct.l, info.p, info.l);
264
265			require (!memcmp (h.prk, prk_correct.p, prk_correct.l));
266			require (!memcmp (okm , okm_correct.p, okm_correct.l));
267			}
268			}
269