Make string_util::WriteInto() DCHECK() that the supplied |length_with_null| > 1, meaning that the...

crypto/encryptor.h

 // 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.
 
 #ifndef CRYPTO_ENCRYPTOR_H_
 #define CRYPTO_ENCRYPTOR_H_
 #pragma once
 
 #include <string>
 
@@ skipping 43 matching lines @@
       uint64 components64[2];
     } counter_;
   };
 
   Encryptor();
   virtual ~Encryptor();
 
   // Initializes the encryptor using |key| and |iv|. Returns false if either the
   // key or the initialization vector cannot be used.
   //
-  // When |mode| is CTR then |iv| should be empty.
+  // If |mode| is CBC, |iv| must not be empty; if it is CTR, then |iv| must be
+  // empty.
   bool Init(SymmetricKey* key, Mode mode, const base::StringPiece& iv);
 
-  // Encrypts |plaintext| into |ciphertext|.
+  // Encrypts |plaintext| into |ciphertext|.  |plaintext| may only be empty if
+  // the mode is CBC.
   bool Encrypt(const base::StringPiece& plaintext, std::string* ciphertext);
 
-  // Decrypts |ciphertext| into |plaintext|.
+  // Decrypts |ciphertext| into |plaintext|.  |ciphertext| must not be empty.
   bool Decrypt(const base::StringPiece& ciphertext, std::string* plaintext);
 
   // Sets the counter value when in CTR mode. Currently only 128-bits
   // counter value is supported.
   //
   // Returns true only if update was successful.
   bool SetCounter(const base::StringPiece& counter);
 
   // TODO(albertb): Support streaming encryption.
 
@@ skipping 47 matching lines @@
   std::string iv_;
 #elif defined(OS_WIN)
   ScopedHCRYPTKEY capi_key_;
   DWORD block_size_;
 #endif
 };
 
 }  // namespace crypto
 
 #endif  // CRYPTO_ENCRYPTOR_H_