Simplify AuthenticationMethod type and PIN hash handling.

remoting/host/pin_hash.h

 // Copyright (c) 2012 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 REMOTING_HOST_PIN_HASH_H_
 #define REMOTING_HOST_PIN_HASH_H_
 
 #include <string>
 
 namespace remoting {
 
 // Creates a Me2Me shared-secret hash, consisting of the hash method, and the
 // hashed host ID and PIN.
 std::string MakeHostPinHash(const std::string& host_id, const std::string& pin);
 
+// Parse string representation of a shared secret hash. The value can be either
+// "plain:<pin_in_base64>" or "hmac:<pin_hmac_in_base64>". In the first case the
+// returned value is automatically hashed. False is returned if |value| is in
+// invalid format.
+bool ParsePinHashFromConfig(const std::string& value,
+                            const std::string& host_id,
+                            std::string* pin_hash_out);
+
 // Extracts the hash function from the given hash, uses it to calculate the
 // hash of the given host ID and PIN, and compares that hash to the given hash.
 // Returns true if the calculated and given hashes are equal.
 bool VerifyHostPinHash(const std::string& hash,
                        const std::string& host_id,
                        const std::string& pin);
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_PIN_HASH_