Relanding Porting of HKDF changes from server.

Added a2b_hex function to move common code in hkdf_unittest.cc and to make it similar to CL - 40300624. Merge internal CL: 40300624 Original approved CL: https://chromiumcodereview.appspot.com/12326029/ R=agl@chromium.org, rsleevi@chromium.org Review URL: https://chromiumcodereview.appspot.com/12335045 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@184306 0039d316-1c4b-4281-b951-d872f2087c98
marcosholgado · Feb 23, 2013 · 48b581d · 48b581d
1 parent 8bdcb66
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diff --git a/crypto/crypto.gyp b/crypto/crypto.gyp
@@ -200,6 +200,8 @@
         'encryptor.h',
         'encryptor_nss.cc',
         'encryptor_openssl.cc',
+        'hkdf.cc',
+        'hkdf.h',
         'hmac_nss.cc',
         'hmac_openssl.cc',
         'mac_security_services_lock.cc',
@@ -264,6 +266,7 @@
         'ec_signature_creator_unittest.cc',
         'encryptor_unittest.cc',
         'ghash_unittest.cc',
+        'hkdf_unittest.cc',
         'hmac_unittest.cc',
         'nss_util_unittest.cc',
         'p224_unittest.cc',

diff --git a/crypto/hkdf.cc b/crypto/hkdf.cc
@@ -0,0 +1,92 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crypto/hkdf.h"
+
+#include "base/logging.h"
+#include "crypto/hmac.h"
+
+namespace crypto {
+
+const size_t kSHA256HashLength = 32;
+
+HKDF::HKDF(const base::StringPiece& secret,
+           const base::StringPiece& salt,
+           const base::StringPiece& info,
+           size_t key_bytes_to_generate,
+           size_t iv_bytes_to_generate) {
+  // https://tools.ietf.org/html/rfc5869#section-2.2
+  base::StringPiece actual_salt = salt;
+  char zeros[kSHA256HashLength];
+  if (actual_salt.empty()) {
+    // If salt is not given, HashLength zeros are used.
+    memset(zeros, 0, sizeof(zeros));
+    actual_salt.set(zeros, sizeof(zeros));
+  }
+
+  // Perform the Extract step to transform the input key and
+  // salt into the pseudorandom key (PRK) used for Expand.
+  HMAC prk_hmac(HMAC::SHA256);
+  bool result = prk_hmac.Init(actual_salt);
+  DCHECK(result);
+
+  // |prk| is a pseudorandom key (of kSHA256HashLength octets).
+  uint8 prk[kSHA256HashLength];
+  DCHECK_EQ(sizeof(prk), prk_hmac.DigestLength());
+  result = prk_hmac.Sign(secret, prk, sizeof(prk));
+  DCHECK(result);
+
+  // https://tools.ietf.org/html/rfc5869#section-2.3
+  // Perform the Expand phase to turn the pseudorandom key
+  // and info into the output keying material.
+  const size_t material_length =
+      2*key_bytes_to_generate + 2*iv_bytes_to_generate;
+  const size_t n = (material_length + kSHA256HashLength-1) /
+                   kSHA256HashLength;
+  DCHECK_LT(n, 256u);
+
+  output_.resize(n * kSHA256HashLength);
+  base::StringPiece previous;
+
+  char* buf = new char[kSHA256HashLength + info.size() + 1];
+  uint8 digest[kSHA256HashLength];
+
+  HMAC hmac(HMAC::SHA256);
+  result = hmac.Init(prk, sizeof(prk));
+  DCHECK(result);
+
+  for (size_t i = 0; i < n; i++) {
+    memcpy(buf, previous.data(), previous.size());
+    size_t j = previous.size();
+    memcpy(buf + j, info.data(), info.size());
+    j += info.size();
+    buf[j++] = static_cast<char>((i + 1) & 0xFF);
+
+    result = hmac.Sign(base::StringPiece(buf, j), digest, sizeof(digest));
+    DCHECK(result);
+
+    memcpy(&output_[i*sizeof(digest)], digest, sizeof(digest));
+    previous = base::StringPiece(reinterpret_cast<char*>(digest),
+                                 sizeof(digest));
+  }
+
+  size_t j = 0;
+  client_write_key_ = base::StringPiece(reinterpret_cast<char*>(&output_[j]),
+                                        key_bytes_to_generate);
+  j += key_bytes_to_generate;
+  server_write_key_ = base::StringPiece(reinterpret_cast<char*>(&output_[j]),
+                                        key_bytes_to_generate);
+  j += key_bytes_to_generate;
+  client_write_iv_ = base::StringPiece(reinterpret_cast<char*>(&output_[j]),
+                                       iv_bytes_to_generate);
+  j += iv_bytes_to_generate;
+  server_write_iv_ = base::StringPiece(reinterpret_cast<char*>(&output_[j]),
+                                       iv_bytes_to_generate);
+  delete[] buf;
+}
+
+HKDF::~HKDF() {
+}
+
+}  // namespace crypto
diff --git a/crypto/hkdf.h b/crypto/hkdf.h
@@ -0,0 +1,64 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CRYPTO_HKDF_H_
+#define CRYPTO_HKDF_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/string_piece.h"
+#include "build/build_config.h"
+#include "crypto/crypto_export.h"
+
+namespace crypto {
+
+// HKDF implements the key derivation function specified in RFC 5869 (using
+// SHA-256) and outputs key material, as needed by QUIC.
+// See https://tools.ietf.org/html/rfc5869 for details.
+class CRYPTO_EXPORT HKDF {
+ public:
+  // |secret|: The input shared secret (or, from RFC 5869, the IKM).
+  // |salt|: an (optional) public salt / non-secret random value. While
+  // optional, callers are strongly recommended to provide a salt. There is no
+  // added security value in making this larger than the SHA-256 block size of
+  // 64 bytes.
+  // |info|: an (optional) label to distinguish different uses of HKDF. It is
+  // optional context and application specific information (can be a zero-length
+  // string).
+  // |key_bytes_to_generate|: the number of bytes of key material to generate.
+  // |iv_bytes_to_generate|: the number of bytes of IV to generate.
+  HKDF(const base::StringPiece& secret,
+       const base::StringPiece& salt,
+       const base::StringPiece& info,
+       size_t key_bytes_to_generate,
+       size_t iv_bytes_to_generate);
+  virtual ~HKDF();
+
+  base::StringPiece client_write_key() const {
+    return client_write_key_;
+  }
+  base::StringPiece client_write_iv() const {
+    return client_write_iv_;
+  }
+  base::StringPiece server_write_key() const {
+    return server_write_key_;
+  }
+  base::StringPiece server_write_iv() const {
+    return server_write_iv_;
+  }
+
+ private:
+  std::vector<uint8> output_;
+
+  base::StringPiece client_write_key_;
+  base::StringPiece server_write_key_;
+  base::StringPiece client_write_iv_;
+  base::StringPiece server_write_iv_;
+};
+
+}  // namespace crypto
+
+#endif  // CRYPTO_HKDF_H_
diff --git a/crypto/hkdf_unittest.cc b/crypto/hkdf_unittest.cc
@@ -0,0 +1,94 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crypto/hkdf.h"
+
+#include <string>
+
+#include "base/strings/string_number_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using crypto::HKDF;
+
+namespace test {
+namespace {
+
+struct HKDFTest {
+  const char* key_hex;
+  const char* salt_hex;
+  const char* info_hex;
+  const char* output_hex;
+};
+
+// These test cases are taken from
+// https://tools.ietf.org/html/rfc5869#appendix-A.
+static const HKDFTest kHKDFTests[] = {{
+    "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
+    "000102030405060708090a0b0c",
+    "f0f1f2f3f4f5f6f7f8f9",
+    "3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5"
+    "b887185865",
+  }, {
+    "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f2021222324"
+    "25262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f40414243444546474849"
+    "4a4b4c4d4e4f",
+    "606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f8081828384"
+    "85868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9"
+    "aaabacadaeaf",
+    "b0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4"
+    "d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9"
+    "fafbfcfdfeff",
+    "b11e398dc80327a1c8e7f78c596a49344f012eda2d4efad8a050cc4c19afa97c59045a99ca"
+    "c7827271cb41c65e590e09da3275600c2f09b8367793a9aca3db71cc30c58179ec3e87c14c"
+    "01d5c1f3434f1d87",
+  }, {
+    "0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b",
+    "",
+    "",
+    "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d9d201395fa"
+    "a4b61a96c8",
+  },
+};
+
+TEST(HKDFTest, HKDF) {
+  for (size_t i = 0; i < arraysize(kHKDFTests); i++) {
+    const HKDFTest& test(kHKDFTests[i]);
+    SCOPED_TRACE(i);
+
+    std::vector<uint8> data;
+    ASSERT_TRUE(base::HexStringToBytes(test.key_hex, &data));
+    const std::string key(reinterpret_cast<char*>(&data[0]), data.size());
+
+    data.clear();
+    // |salt_hex| is optional and may be empty.
+    std::string salt(test.salt_hex);
+    if (!salt.empty()) {
+      ASSERT_TRUE(base::HexStringToBytes(salt, &data));
+      salt.assign(reinterpret_cast<char*>(&data[0]), data.size());
+    }
+
+    data.clear();
+    // |info_hex| is optional and may be empty.
+    std::string info(test.info_hex);
+    if (!info.empty()) {
+      ASSERT_TRUE(base::HexStringToBytes(info, &data));
+      info.assign(reinterpret_cast<char*>(&data[0]), data.size());
+    }
+
+    data.clear();
+    ASSERT_TRUE(base::HexStringToBytes(test.output_hex, &data));
+    const std::string expected(reinterpret_cast<char*>(&data[0]), data.size());
+
+    // We set the key_length to the length of the expected output and then take
+    // the result from the first key, which is the client write key.
+    HKDF hkdf(key, salt, info, expected.size(), 0);
+
+    ASSERT_EQ(expected.size(), hkdf.client_write_key().size());
+    EXPECT_EQ(0, memcmp(expected.data(), hkdf.client_write_key().data(),
+                        expected.size()));
+  }
+}
+
+}  // namespace
+}  // namespace test