From 1375729f44ae53cd1f9f6bb9e299162f0d1aa4a5 Mon Sep 17 00:00:00 2001
From: mvahabi <mvahabi@ucsc.edu>
Date: Tue, 18 Mar 2025 18:58:27 -0700
Subject: [PATCH] brought back the code comment blocks
---
oram.cpp | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)
diff --git a/oram.cpp b/oram.cpp
index 36b26dc..956dab5 100644
--- a/oram.cpp
+++ b/oram.cpp
@@ -11,24 +11,26 @@
using namespace std;
// ORAM parameters (for demonstration)
-const int TREE_HEIGHT = 3;
-const int BUCKET_CAPACITY = 3;
-const int NUM_LEAVES = 1 << TREE_HEIGHT;
-const int NUM_BUCKETS = (1 << (TREE_HEIGHT + 1)) - 1;
-const string STATE_FILE = "oram_state.db";
+const int TREE_HEIGHT = 5; // Height of the tree (number of levels - 1)
+const int BUCKET_CAPACITY = 5; // Maximum number of blocks per bucket
+const int NUM_LEAVES = 1 << TREE_HEIGHT; // 2^TREE_HEIGHT leaves
+const int NUM_BUCKETS = (1 << (TREE_HEIGHT + 1)) - 1; // Total number of buckets in a complete binary tree
+const string STATE_FILE = "oram_state.db"; // File to persist ORAM state
+
// Structure for a data block.
struct Block {
- string id;
- string data;
+ string id; // Hashed block identifier (SHA-256 hex string)
+ string data; // Block data (e.g. hex-encoded string)
};
+
// Global ORAM state:
-vector<vector<Block>> tree;
-unordered_map<string, int> posMap;
-vector<Block> stash;
+vector<vector<Block>> tree; // Tree: vector of buckets (each bucket is a vector of blocks)
+unordered_map<string, int> posMap; // Position map: maps block id (hashed string) to assigned leaf
+vector<Block> stash; // Stash: temporary storage for blocks during accesses
-// RNG for leaf assignment
+// Random number generator for new leaf assignments.
mt19937 rng(random_device{}());
// Helper: path indices from root to leaf
@@ -40,17 +42,17 @@ vector<int> getPathIndices(int leaf) {
if (idx == 0) break;
idx = (idx - 1) / 2;
}
- reverse(path.begin(), path.end());
+ //reverse(path.begin(), path.end());
return path;
}
-// Helper: random leaf
+// Helper: Generate a random leaf number between 0 and NUM_LEAVES-1.
int getRandomLeaf() {
uniform_int_distribution<int> dist(0, NUM_LEAVES - 1);
return dist(rng);
}
-// Load ORAM state
+// Load ORAM state firm the persistent file.
void loadState() {
ifstream infile(STATE_FILE);
if (!infile) {
@@ -117,7 +119,7 @@ void loadState() {
infile.close();
}
-// Save ORAM state
+// Save ORAM state frim the persistent file
void saveState() {
ofstream outfile(STATE_FILE, ios::trunc);
outfile << "#tree" << endl;
@@ -143,7 +145,7 @@ void saveState() {
outfile.close();
}
-// Eviction
+// Eviction function with dummy block insertion.
void evictPath(vector<int> path) {
reverse(path.begin(), path.end());
for (int bucketIdx : path) {
@@ -175,7 +177,7 @@ void evictPath(vector<int> path) {
}
}
-// Access
+// ORAM access function.
string accessBlock(const string &blockId, const string &newData, bool isWrite) {
int oldLeaf;
if (posMap.find(blockId) == posMap.end()) {
--
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