Blockchain Diary

A simple on-chain diary built entirely in Solidity — no imports, no constructors.
Users can timestamp and store diary entries directly on the blockchain, ensuring permanence, transparency, and authenticity.

🌍 Overview

Blockchain Diary enables users to record diary entries on-chain, permanently tied to their Ethereum wallet address.
Each entry automatically receives a blockchain timestamp (block.timestamp) and remains immutable once stored.

The contract is designed to be:

• Minimalistic: no external dependencies or complex logic

• Transparent: anyone can verify entries on-chain

• Immutable: no editing or deletion for historical integrity

⚙️ Features

✅ 100% Solidity — no imports, no constructors
✅ Timestamped entries for each Ethereum address
✅ Gas-optimized logging using events
✅ Option to emit lightweight notes without storage
✅ View entries, total count, or specific user ranges
✅ Tamper-proof and verifiable on-chain history

🧠 Smart Contract Details

• Name: BlockchainDiary

• Compiler Version: ^0.8.19

• License: MIT

• Deployed Address: 0x4230E95d23Ce7adb4d692f1c3c56094FED7a89e9

• Network: Any EVM-compatible blockchain (Ethereum, Polygon, BSC, etc.)

🚀 Deployment Guide

🧩 Using Remix IDE

1. Open Remix Ethereum IDE

2. Create a new file BlockchainDiary.sol

3. Paste the contract code

4. Select Solidity Compiler 0.8.19

5. Compile the contract

6. Under Deploy & Run Transactions, choose:

   • Remix VM (local testing), or

   • Injected Provider (MetaMask) for live networks

7. Click Deploy

8. Copy and save the Contract Address

💡 Usage

➕ Add a Diary Entry

Users can store text (plain, encrypted, or IPFS CID).
Each entry is recorded with:

• msg.sender → your Ethereum address

• block.timestamp → exact time of submission

Example use cases:

• Daily journaling on-chain

• Immutable proof of statements or creative ideas

• Timestamped academic notes or digital art entries

🔍 Retrieve Data

• entriesCount(address) → Get total number of entries for a user

• getEntry(address, index) → Fetch specific entry and timestamp

• getMyLastEntry() → Get your most recent diary entry

• getEntriesRange(address, start, end) → Fetch multiple entries

• entryContentHash(address, index) → Verify entry integrity with keccak256 hash

• addEventNote(string note) → Emit quick note event without storing data

🪄 Example Use Cases

• Personal blockchain diary or journal

• Permanent storage of quotes, achievements, or thoughts

• Timestamped proof of authorship or digital creation

• Transparent logging for research or documentation

• Off-chain integration using event logs and hashes

⚠️ Important Notes

• All on-chain data is public. Avoid posting private or sensitive content directly.

• For privacy, store encrypted text or IPFS hashes instead of raw text.

• String storage increases gas cost — prefer shorter entries or note events.

• Entries cannot be modified or deleted once created.

🧑‍💻 Project Information

📬 License

This project is licensed under the MIT License.
You are free to use, modify, and distribute the code with proper credit to the author.