Don't enforce the old HMAC key size requirement in FIPS 198 Sec. 3.

crypto/hmac_win.cc

 // Copyright (c) 2011 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/hmac.h"
 
 #include <windows.h>
 #include <wincrypt.h>
 
 #include <algorithm>
@@ skipping 86 matching lines @@
 }
 
 bool HMAC::Init(const unsigned char* key, int key_length) {
   if (plat_->provider_ || plat_->key_ || !plat_->raw_key_.empty()) {
     // Init must not be called more than once on the same HMAC object.
     NOTREACHED();
     return false;
   }
 
   if (hash_alg_ == SHA256) {
-    if (key_length < SHA256_LENGTH / 2)
-      return false;  // Key is too short.
     plat_->raw_key_.assign(key, key + key_length);
     return true;
   }
 
   if (!CryptAcquireContext(plat_->provider_.receive(), NULL, NULL,
                            PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) {
     NOTREACHED();
     return false;
   }
 
@@ skipping 70 matching lines @@
 
   if (!CryptHashData(hash, reinterpret_cast<const BYTE*>(data.data()),
                      static_cast<DWORD>(data.size()), 0))
     return false;
 
   DWORD sha1_size = digest_length;
   return !!CryptGetHashParam(hash, HP_HASHVAL, digest, &sha1_size, 0);
 }
 
 }  // namespace crypto