Separate the key setting code in the constructor of HMAC class into the Init...

base/hmac_win.cc

 // Copyright (c) 2006-2008 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 "base/hmac.h"
 
 #include <windows.h>
 #include <wincrypt.h>
 
 #include <algorithm>
 #include <vector>
 
 #include "base/logging.h"
 
 namespace base {
 
 struct HMACPlatformData {
   // Windows Crypt API resources.
   HCRYPTPROV provider_;
   HCRYPTHASH hash_;
   HCRYPTKEY hkey_;
 };
 
-HMAC::HMAC(HashAlgorithm hash_alg, const unsigned char* key, int key_length)
+HMAC::HMAC(HashAlgorithm hash_alg)
     : hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
+  // Only SHA-1 digest is supported now.
+  DCHECK(hash_alg_ == SHA1);
+}
+
+bool HMAC::Init(const unsigned char *key, int key_length) {
+  if (plat_->provider_ || plat_->hkey_) {
+    // Init must not be called more than once on the same HMAC object.
+    NOTREACHED();
+    return false;
+  }
+
   if (!CryptAcquireContext(&plat_->provider_, NULL, NULL,
-                           PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
+                           PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) {
+    NOTREACHED();
     plat_->provider_ = NULL;
+    return false;
+  }
 
   // This code doesn't work on Win2k because PLAINTEXTKEYBLOB and
   // CRYPT_IPSEC_HMAC_KEY are not supported on Windows 2000.  PLAINTEXTKEYBLOB
   // allows the import of an unencrypted key.  For Win2k support, a cubmbersome
   // exponent-of-one key procedure must be used:
   //     http://support.microsoft.com/kb/228786/en-us
   // CRYPT_IPSEC_HMAC_KEY allows keys longer than 16 bytes.
 
   struct KeyBlob {
     BLOBHEADER header;
     DWORD key_size;
     BYTE key_data[1];
   };
   size_t key_blob_size = std::max(offsetof(KeyBlob, key_data) + key_length,
                                   sizeof(KeyBlob));
   std::vector<BYTE> key_blob_storage = std::vector<BYTE>(key_blob_size);
   KeyBlob* key_blob = reinterpret_cast<KeyBlob*>(&key_blob_storage[0]);
   key_blob->header.bType = PLAINTEXTKEYBLOB;
   key_blob->header.bVersion = CUR_BLOB_VERSION;
   key_blob->header.reserved = 0;
   key_blob->header.aiKeyAlg = CALG_RC2;
   key_blob->key_size = key_length;
   memcpy(key_blob->key_data, key, key_length);
 
   if (!CryptImportKey(plat_->provider_, &key_blob_storage[0],
                       key_blob_storage.size(), 0, CRYPT_IPSEC_HMAC_KEY,
                       &plat_->hkey_)) {
+    NOTREACHED();
     plat_->hkey_ = NULL;
+    return false;
   }
 
   // Destroy the copy of the key.
   SecureZeroMemory(key_blob->key_data, key_length);
+
+  return true;
 }
 
 HMAC::~HMAC() {
-  if (plat_->hkey_)
-    CryptDestroyKey(plat_->hkey_);
-  if (plat_->hash_)
-    CryptDestroyHash(plat_->hash_);
-  if (plat_->provider_)
-    CryptReleaseContext(plat_->provider_, 0);
+  BOOL ok;
+  if (plat_->hkey_) {
+    ok = CryptDestroyKey(plat_->hkey_);
+    DCHECK(ok);
+  }
+  if (plat_->hash_) {
+    ok = CryptDestroyHash(plat_->hash_);
+    DCHECK(ok);
+  }
+  if (plat_->provider_) {
+    ok = CryptReleaseContext(plat_->provider_, 0);
+    DCHECK(ok);
+  }
 }
 
 bool HMAC::Sign(const std::string& data,
                 unsigned char* digest,
                 int digest_length) {
   if (!plat_->provider_ || !plat_->hkey_)
     return false;
 
   if (hash_alg_ != SHA1) {
     NOTREACHED();
@@ skipping 17 matching lines @@
     return false;
 
   DWORD sha1_size = digest_length;
   if (!CryptGetHashParam(plat_->hash_, HP_HASHVAL, digest, &sha1_size, 0))
     return false;
 
   return true;
 }
 
 }  // namespace base