> ## Documentation Index
> Fetch the complete documentation index at: https://docs.shieldhq.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Glossary

> Web3 and SHIELD terminology explained

# Glossary

## A

### Access Policy

A set of rules defining who can access content, when, and how many times. Stored on the Base blockchain.

### AES-GCM

Advanced Encryption Standard - Galois/Counter Mode. A symmetric encryption algorithm providing confidentiality and authentication.

### Attempt

One instance of a recipient trying to access content. Tracked on-chain via `logAttempt()`.

## B

### Base

An Ethereum Layer 2 blockchain by Coinbase. SHIELD deploys its smart contracts on Base.

### Blockchain

A distributed, immutable ledger. SHIELD uses Base for transparent, trustless access control.

## C

### CID (Content Identifier)

A unique hash identifying content on IPFS. SHIELD encrypted content is referenced by CID.

### Contract

A smart contract on the blockchain. SHIELD's `Shield.sol` contract manages access policies.

## D

### dApp (Decentralized Application)

An application with backend running on blockchain. SHIELD is a dApp.

### Decryption

Converting encrypted content back to plaintext. Happens client-side in SHIELD.

## E

### EIP-4361

Ethereum Improvement Proposal for Sign-In with Ethereum (SIWE). SHIELD uses this for authentication.

### Encryption

Converting plaintext to ciphertext. SHIELD uses AES-GCM 256 client-side.

### End-to-End Encryption

Encryption where only sender and recipient can decrypt. SHIELD implements this.

## F

### Faucet

A service providing free test ETH. Use [Alchemy Faucet](https://www.alchemy.com/faucets/base-sepolia) for Base Sepolia.

## G

### Gas

Fee paid to execute transactions on blockchain. Paid in ETH on Base.

### Gateway

A server providing HTTP access to IPFS content. SHIELD uses Pinata's gateway.

## H

### Hash

A fixed-size output from a cryptographic function. Used for policy IDs and CIDs.

### Hardhat

Ethereum development environment. Used for SHIELD contract development.

## I

### IPFS (InterPlanetary File System)

Decentralized file storage. SHIELD stores encrypted content on IPFS via Pinata.

### IV (Initialization Vector)

A random value ensuring same plaintext encrypts differently each time. 96 bits in AES-GCM.

## J

### JWT (JSON Web Token)

A token format for session management. SHIELD uses JWT for API sessions.

## K

### Key

A secret value for encryption/decryption. In SHIELD, keys are 256-bit random values.

## L

### Link (Secure Link)

A URL containing policyId and secretKey. Created once, shown once, never recoverable.

## M

### Mainnet

The production blockchain network. Base mainnet is where real value is at stake.

### Max Attempts

Maximum times content can be accessed. Set by sender.

### Metadata

Information about content (size, type) but not the content itself. Stored off-chain.

## N

### Next.js

React framework. Powers SHIELD frontend.

### Nonce

A number used once. Prevents replay attacks in SIWE.

## P

### Pinata

IPFS pinning service. SHIELD uses Pinata to persist encrypted content.

### Policy ID

Unique identifier for an access policy. Keccak256 hash stored on-chain.

## R

### Recipient

The wallet address authorized to access content. Set when creating a policy.

### Revoke

Invalidate a policy before expiration. Irreversible.

## S

### Secret Key

The decryption key. Embedded in URL fragment, never sent to server.

### Sender

The creator of a secure link. Pays gas for policy creation.

### Sepolia

Testnet for Base. Used for development and testing.

### SIWE (Sign-In with Ethereum)

Authentication standard using Ethereum signatures. Replaces passwords.

### Smart Contract

Program running on blockchain. SHIELD's `Shield.sol` enforces access rules.

## T

### Tailwind CSS

Utility-first CSS framework. Styles SHIELD UI.

### Testnet

Test blockchain network. No real value, used for testing.

### Transaction

Data submitted to blockchain. Costs gas. SHIELD has `createPolicy` and `logAttempt` transactions.

### Trustless

System requiring no trusted parties. SHIELD's architecture is trustless.

## U

### URL Fragment

Part of URL after `#`. SHIELD puts secret keys here—never sent to server.

## V

### Vercel

Hosting platform. SHIELD frontend deploys to Vercel.

### View Function

Smart contract function that reads state without transaction. `isPolicyValid` is a view function.

## W

### Wallet

Software for managing private keys. MetaMask, Rainbow, etc.

### WalletConnect

Protocol for connecting wallets to dApps. SHIELD uses WalletConnect.

### Web Crypto API

Browser API for cryptography. SHIELD uses it for AES-GCM.

### Web3

Decentralized web ecosystem. SHIELD is a web3 application.

## Z

### Zero Address

`0x000...000`. Invalid address. Cannot be used as recipient.