Certificate Transparency: MerkleTreeLeaf, MerkleAuditProof improvements.

net/cert/merkle_tree_leaf.h

Index: net/cert/merkle_tree_leaf.h
diff --git a/net/cert/merkle_tree_leaf.h b/net/cert/merkle_tree_leaf.h
index 8f314f56a70641142300f8c6d556ab349178966b..21217bb6ec5c454e53c12e82cf2ff6e0b8cdf4f4 100644
--- a/net/cert/merkle_tree_leaf.h
+++ b/net/cert/merkle_tree_leaf.h
@@ -19,15 +19,25 @@ class X509Certificate;
 namespace ct {
 
 // Represents a MerkleTreeLeaf as defined in RFC6962, section 3.4.
-// Has all the data as the MerkleTreeLeaf defined in the RFC, arranged
-// slightly differently.
+// The goal of this struct is to represent the Merkle tree entry such that
+// all details are easily accessible and a leaf hash can be easily calculated
+// for the entry.
+//
+// As such, it has all the data as the MerkleTreeLeaf defined in the RFC,
+// but it is not identical to the structure in the RFC for the following
+// reasons:
+// * The version is implicit - it is only used for V1 leaves currently.
+// * the leaf_type is also implicit: There's exactly one leaf type and no
+// new types are planned.
+// * The timestamped_entry's |timestamp| and |extensions| fields are directly
+// accessible.
+// * The timestamped_entry's entry_type can be deduced from |log_entry|.type
 struct NET_EXPORT MerkleTreeLeaf {
   MerkleTreeLeaf();
+  MerkleTreeLeaf(const MerkleTreeLeaf& other);
+  MerkleTreeLeaf(MerkleTreeLeaf&&);
   ~MerkleTreeLeaf();
 
-  // The log id this leaf belongs to.
-  std::string log_id;
-
   // Certificate / Precertificate and indication of entry type.
   LogEntry log_entry;
 
@@ -38,13 +48,19 @@ struct NET_EXPORT MerkleTreeLeaf {
   std::string extensions;
 };
 
+// Given a |cert| and an |sct| for that certificate, constructs the
+// representation of this entry in the Merkle tree by filling in
+// |merkle_tree_leaf|.
+// Returns false if it failed to construct the |merkle_tree_leaf|.
 NET_EXPORT bool GetMerkleTreeLeaf(const X509Certificate* cert,
                                   const SignedCertificateTimestamp* sct,
                                   MerkleTreeLeaf* merkle_tree_leaf);
 
-// Sets |*out| to the hash of the Merkle |tree_leaf|, as defined in RFC6962.
-// Returns true if the hash was generated, false if an error occurred.
-NET_EXPORT bool Hash(const MerkleTreeLeaf& tree_leaf, std::string* out);
+// Sets |*out| to the hash of the Merkle |tree_leaf|, as defined in RFC6962,
+// section 3.4. Returns true if the hash was generated, false if an error
+// occurred.
+NET_EXPORT bool HashMerkleTreeLeaf(const MerkleTreeLeaf& tree_leaf,
+                                   std::string* out);
 
 }  // namespace ct