In today’s crypto landscape, many people are hesitant to enter due to the complexity of interacting with digital currencies. Silverbacks Crypto Cash and King Louis Crypto Index Note simplify the process by bridging traditional paper money and digital crypto.

Key Advantages:

• Simplified Onboarding:
  Users can convert physical bills into digital assets without needing to understand complex deposit processes or token approvals. This ease of use makes crypto accessible even to newcomers.

• Familiar Representation:
  By representing value as a digital bill (NFT), the system leverages a familiar concept—paper money—making the transition to digital assets intuitive and less intimidating.

• Enhanced Security:
  Encrypted decryption keys embedded in an NFC chip ensure that only the rightful holder of a physical bill can redeem it, reducing the risk of fraud and unauthorized redemptions.

• Direct Conversion:

  • Silverbacks Crypto Cash: Users can directly redeem their bill for a stablecoin, ensuring a straightforward conversion from paper cash to digital crypto.
  • King Louis Crypto Index Note: Users receive a diversified bundle of tokens (e.g., WBTC, WETH, WLTC), offering exposure to multiple assets through a single note.

• Decentralized Metadata Storage:
  Images and bill metadata are stored on IPFS, ensuring that the data remains immutable, decentralized, and resistant to censorship or data loss.

This solution makes traditional cash-to-crypto conversion easier, safer, and more user-friendly, opening up digital finance to a broader audience.

Silverbacks Crypto Cash and King Louis Crypto Index Note simplify converting physical bills into digital crypto assets with an intuitive, secure process:

1. Bill Setup:
   Each physical bill is preloaded as an NFT (with metadata stored on IPFS) and embeds an NFC chip. The NFC chip holds a URL that includes an encrypted private key alongside its public key. A QR code on the bill encodes the decryption key.

2. Wallet Connection:
   Users connect their web3 wallet via the DApp interface. Clear, real-time guidance helps even non‑crypto users navigate the process.

3. Redemption Process:

   • The user taps the NFC chip to retrieve the URL and encrypted key.
   • They then scan the QR code to capture the decryption key.
   • Off‑chain, the decryption key is used to decrypt the encrypted private key.
   • The decrypted private key generates a signature that authorizes the vault to burn the NFT.
   • Upon burning, the vault transfers the corresponding crypto asset to the user’s wallet:
     • Silverbacks Crypto Cash: Credits a fixed stablecoin amount (e.g., $100).
     • King Louis Crypto Index Note: Transfers a preset bundle of tokens (e.g., WBTC, WETH, WLTC).

4. User Guidance & Security:
   The interface provides real‑time logs and clear status messages throughout, ensuring a secure and seamless conversion from paper to digital crypto.

Silverbacks Crypto Cash and King Louis Crypto Index Note convert physical bills into digital crypto assets by combining NFT technology, decentralized storage, and secure NFC/QR-based redemption.

Overview of the Solution

Preloaded digital bills are minted as NFTs that represent a fixed crypto value. Bill metadata (images, descriptions, face values) is stored on IPFS. Each physical bill contains an NFC chip that holds a URL with an encrypted private key and its public key. A QR code on the bill encodes the decryption key.

Core Functionality

• Bill Issuance:

  • Silverbacks Crypto Cash: Represents a fixed value (e.g., $100) in stablecoins.
  • King Louis Crypto Index Note: Represents a predefined token bundle (e.g., WBTC, WETH, WLTC).
    Metadata is stored on IPFS and linked via the NFT; the NFC chip provides the redemption URL.

• Secure Redemption:
  Users scan the QR code to retrieve the decryption key, which is used to decrypt the encrypted private key from the NFC chip’s URL. This decrypted private key generates a signature that:

  • Burns the NFT, and
  • Triggers the vault to transfer the corresponding crypto assets (stablecoin or token bundle) to the user’s wallet.

Key Implementation Details

• Smart Contracts:

  • NFT Contracts: (SilverbacksNFT and MultiTokenNFT) store IPFS token URIs and face values.
  • Vault Contracts: (SilverbacksVault and MultiTokenVault) manage funds, mint NFTs, and execute redemptions.

• Frontend Application:
  Built with React and ethers.js, it handles wallet integration, NFC/QR scanning, decryption, and transaction initiation with clear, real‑time user guidance.

• Security:
  AES‑CTR encryption via CryptoJS secures the private key on the NFC chip, ensuring only the rightful bill holder can redeem it.

Product Integrations

Our solution leverages several APIs, libraries, and hardware integrations to deliver a secure and seamless experience for converting physical bills into digital crypto assets:

• IPFS (InterPlanetary File System):
  Utilized via the IPFS HTTP client to store NFT metadata and images. This decentralized storage ensures that bill-related data is immutable and globally accessible.

• Coingecko API:
  Integrated to fetch real-time token prices (e.g., WBTC, WETH, WLTC) used by King Louis Crypto Index Notes, allowing users to view the current USD value of the token bundle backing their NFT.

• NFC Integration:
  Each physical bill includes an NFC chip that stores a URL embedding both the encrypted decryption key and the public key. This enables users to tap their NFC-enabled devices to retrieve secure data for redemption.

• QR Code Generation:
  The

  qrcode

  library generates QR codes that encode decryption keys. These QR codes are printed on the bills, providing an alternative secure method for linking the physical bill to its digital representation.

• CryptoJS:
  Employed for AES‑CTR encryption/decryption to safeguard the decryption key, ensuring that only the rightful bill holder can access and redeem the NFT.

• Wallet Provider APIs:
  By interfacing with

  window.ethereum

  (supporting MetaMask, Coinbase Wallet, etc.), the platform manages wallet connections, transaction signing, and seamless network switching.

• ethers.js:
  Serves as the primary library for smart contract interactions, managing tasks such as NFT minting, redemption processing, and on‑chain data queries.

• QR Barcode Scanner:
  Integrated via the

  react-qr-barcode-scanner

  library, this feature enables users to scan QR codes directly within the DApp for a streamlined, secure redemption process.

• Bridging Physical Cash and Digital Crypto:
  Our solution uniquely converts physical bills into digital crypto assets using NFTs. Unlike traditional platforms that require complex deposit and approval steps, users simply redeem a physical bill—via NFC and QR code scanning—for crypto, making the process accessible even for non‑crypto natives.

• Dual Product Offerings:

  • Silverbacks Crypto Cash:
    Directly converts a physical bill into a stablecoin, echoing the familiar concept of cash.
  • King Louis Crypto Index Note:
    Bundles multiple tokens (e.g., WBTC, WETH, WLTC) into a single digital note, providing diversified crypto exposure in one product.

• Multi-Factor Secure Redemption:
  Each bill incorporates an NFC chip that stores a secure URL (with an encrypted private key and public key), while a printed QR code carries the decryption key. This dual-layer security ensures only the rightful bill holder can redeem the digital asset.

• Decentralized and Immutable Data Storage:
  By storing images and metadata on IPFS, our system guarantees that bill-related data remains tamper-proof and permanently accessible.

• Streamlined User Experience:
  We abstract away the technical complexities of blockchain interactions (such as token approvals and deposits) behind an intuitive interface, reducing friction and building user trust.

• Enhanced Onboarding:
  Compared to other crypto solutions, our approach minimizes user involvement in complex transactions, offering a secure, accessible pathway from traditional cash to digital crypto assets.

• Bill Creation & Loading:
  The manual process to create, print, and load 4 bills (≈20 minutes) was chosen to rapidly validate our core concept.
  Future: Automate batch generation and printing to streamline bill loading.

• Encryption & QR Code Integration:
  We implemented AES‑CTR encryption with a static IV (via CryptoJS) to quickly generate encrypted keys for QR codes on bills.
  Future: Upgrade to dynamic IVs and robust key management for enhanced security.

• Simplified User Experience:
  Complex blockchain operations (like deposits and token approvals) are abstracted to provide a seamless redemption process for users.
  Future: Integrate optional advanced features (e.g., dynamic fee calculations) while preserving ease of use.

• Modular Smart Contract Design:
  Our contracts are designed to be modular and deployable across multiple networks (e.g., Sepolia, Linea, Somnia), which led to compromises in configurability and error handling.
  Future: Improve network support with enhanced configurability and comprehensive monitoring.

• Rapid Prototyping & Logging:
  Extensive console logging was used to expedite debugging, though it lacks production-level robustness.
  Future: Implement production-grade logging and error monitoring.